Timeline of Deworm the World Initiative

This is a timeline of Deworm the World Initiative, a program founded in 2007 that helps governments run school-based mass deworming for parasitic worms. Incubated by Innovations for Poverty Action and run since 2013 by the nonprofit Evidence Action, it has supported programs in India, Kenya, Nigeria, and Pakistan, reaching hundreds of millions of children, amid a long-running debate over the evidence for mass deworming.

Sample questions

The following are some interesting questions that can be answered by reading this timeline:

• What research led to the creation of Deworm the World, and how did follow-up studies change the case for deworming?
  • Sort the full timeline by "Event type" and look for the group of rows with value "Research".
  • You will see the 1990 Montserrat study of school-targeted deworming, the 2004 Econometrica paper on the Kenya trial, Hoyt Bleakley's 2007 study of hookworm eradication in the American South, Kremer and Miguel's 2007 finding that small user fees collapse take-up, baseline worm surveys in Bihar (2010–2011) and Delhi (2011), the 2013 DEVTA trial of one million preschool children in Uttar Pradesh, a 2015 review of when governments should pay for mass deworming, the 2015 lessons-learned paper on Bihar's 2011 campaign, the ten-year "Worms at Work" follow-up (2016), Owen Ozier's study of spillovers to younger siblings (2018), the twenty-year follow-up in PNAS (2021), a 2023 Indian meta-analysis of child worm prevalence, and 2023 evidence that deworming lowered child mortality in the next generation.
• How has the evidence for mass deworming been challenged and defended?
  • Sort the full timeline by "Event type" and look for the group of rows with value "Debate".
  • You will see a 2012 blog debate over that year's Cochrane review, the BMJ's 2013 "Deworming debunked" feature, the 2015 reanalyses and Cochrane review that started the "worm wars" and the original authors' commentary in reply, Ben Goldacre's BuzzFeed essay using the reanalyses to argue for data sharing, Evidence Action's own statement calling the controversy "manufactured", a World Bank economist's review siding with the original study, a Center for Global Development post arguing the original findings were qualified rather than "debunked", a Berkeley economist's defense accusing the reanalysis of "torturing the data", J-PAL and IPA's call for an independent re-appraisal, a Columbia researcher's reanalysis finding the evidence weakened but deworming still a reasonable bet, the PLOS Neglected Tropical Diseases exchanges of 2015 and 2017, a 2016 ethnographic critique of school deworming in East Africa, the 2017 Campbell-linked meta-analysis finding little effect of mass deworming, the 2019 Cochrane update upholding its 2015 conclusions, the Happier Lives Institute's 2022 critique of GiveWell's cost-effectiveness model, and the 2024 meta-analysis the WHO cites as confirming that mass deworming is cost-effective.
• How has GiveWell's assessment of Deworm the World changed over time?
  • Sort the full timeline by "Event type" and look for the group of rows with value "Evaluation".
  • You will see GiveWell's first review (2011), its April 2012 conversation with Deworm the World's managing director, its November 2013 review and the top charity listing that follows it, its response to the 2015 reanalyses, its 2016 explanation that deworming "might have close to zero impact" but remains a worthwhile bet, the 2022 removal from GiveWell's top charities list, the 2023 Founders Pledge recommendation, and the 2026 lookback on India grants.
• Which large government programs did Deworm the World help start?
  • Sort the full timeline by "Event type" and look for the group of rows with value "Program launch".
  • You will see Kenya's national school-based program (2009), Bihar's first statewide program (2011), Delhi's first deworming day (2012), India's first National Deworming Day (2015), and Pakistan's first school deworming day in Islamabad (2019).
• In which countries has Deworm the World worked, and when did it enter each?
  • Sort the full timeline by "Event type" and look for the group of rows with value "Expansion".
  • You will see the 2009 Davos plan to expand into 15 countries, entries for India and West Africa (2009), Nigeria's Ogun State (2010), Vietnam (2014), Madhya Pradesh (2014), Ethiopia (2015), Nigeria (2016), Kenya's lymphatic filariasis program (2018), Pakistan (2019), Malawi (2024), and Tanzania (2026), plus the 2017 peak of over 280 million children treated.
• How has Deworm the World been funded?
  • Sort the full timeline by "Event type" and look for the group of rows with value "Funding".
  • You will see CIFF's five-year support for Kenya (2011), USAID's five-year grant for India (2012), the 2013 Bihar funding gap Deworm the World describes to GiveWell (2012), the first year of GiveWell-driven funding (2014), GiveWell's top-priority $10.8 million recommendation to Good Ventures (2015), Good Ventures' $10.4 million grant (2019), Evidence Action's pandemic-era Paycheck Protection Program loan (2020), its 2022 revenue jump driven by a single donor, GiveWell's January 2023 grant that drops most of Pakistan, GiveWell's 2024 renewal and 2025 exit grants, and Evidence Action's January 2026 appeal as aid for neglected tropical diseases collapses. For year-by-year figures, see the Evidence Action finances table.
• How has the organization behind Deworm the World changed?
  • Sort the full timeline by "Event type" and look for the group of rows with value "Organizational".
  • You will see the 2007 Davos launch, the 2008 incorporation, the 2009 move of its headquarters from London to Washington, its incubation by Innovations for Poverty Action from 2010, the 2013 spin-off into Evidence Action, a 2015 profile of Evidence Action, Alix Zwane's departure as executive director (2015), Kanika Bahl's appointment as CEO (2017), its 2019 exits from Vietnam and Ethiopia, and the 2025 moves to conclude support in Kenya and several Indian states.
• How are individual deworming rounds organized, and how did programs cope with disruptions such as the COVID-19 pandemic?
  • Sort the full timeline by "Event type" and look for the group of rows with value "Implementation".
  • You will see India's first year with two National Deworming Day rounds (August 2016), Kenya's March 2020 deworming wave, after which school closures cancel the rest of the year's treatment, India's switch to door-to-door deworming in late 2020, Kenya's March 2021 restart, organized in under three weeks while the program switches to buying albendazole locally, and the August 2021 round-up of pandemic-era rounds, including Lagos State's first large-scale campaign and Pakistan's use of community health workers.
• What do prevalence surveys show about the impact of deworming programs?
  • Sort the full timeline by "Event type" and look for the group of rows with value "Impact assessment".
  • You will see Bihar's 2015 follow-up survey and GiveWell's caveats about it, the 2019 five-year evaluation of Kenya's program, the 2021–2022 Kenya survey showing an 82% fall in prevalence since 2012, the launch of Pakistan's National Impact Survey in October 2025, and the 2026 results from Nigeria's Cross River State.
• What wider events shaped the case for mass deworming?
  • Sort the full timeline by "Event type" and look for the group of rows with value "Background".
  • You will see the 1910 Rockefeller hookworm campaign that prefigures modern mass deworming, the 1998 start of the Kenya school deworming project, the 2001 World Health Assembly target for treating school-age children, the 2012 London Declaration drug donations, the WHO's 2017 guideline reaffirming large-scale deworming, and the 2019 Nobel Prize for Kremer, Duflo, and Banerjee.
• How have Deworm the World and its government partners planned the scale-up and wind-down of programs?
  • Sort the full timeline by "Event type" and look for the group of rows with value "Strategy".
  • You will see Kremer and Zwane's 2014 stocktaking of the initiative and of the countries that most needed to scale up, and Pakistan's 2023 national strategic framework, which records how COVID-19 school closures stalled the program and sets targets through 2027.

Big picture

Time period	Development summary	More details
1910–1915	Historical precedent	The Rockefeller Sanitary Commission runs a mass hookworm treatment campaign across the American South, treating more than 400,000 people. Research published in 2007 would link it to large gains in schooling and adult income, and it would later be cited as long-run evidence for mass deworming.
1998–2006	Research origins	Economists Michael Kremer and Edward Miguel evaluate a school-based mass deworming project in western Kenya. Their 2004 paper finds that treatment cuts school absenteeism by a quarter and benefits untreated children nearby, which becomes the founding evidence for the initiative. In 2001, the World Health Assembly sets a target of regularly treating most at-risk school-age children.
2007–2012	Founding and first large government programs	After a presentation at the World Economic Forum in Davos, Deworm the World is launched in 2007 and operates as an initiative of Innovations for Poverty Action. It helps Kenya start a national school-based deworming program (2009), supports the first statewide program in the Indian state of Bihar (2011), at the time the largest school-based deworming effort ever conducted, and helps Delhi hold its first deworming day (2012). A 2012 Cochrane review of deworming trials prompts an early public debate over the evidence.
2013–2016	Evidence Action, GiveWell, and rapid scale-up	The program spins off into the new nonprofit Evidence Action in 2013 and becomes a GiveWell top charity the same year. Support extends to Vietnam and the Indian state of Madhya Pradesh (2014), Ethiopia (2015), and Nigeria (2016). India's first National Deworming Day (2015) treats 89 million children in one day, and from 2016 India holds two rounds a year. In 2015, reanalyses of the Kenya trial and an updated Cochrane review question the educational benefits of mass deworming, setting off the "worm wars"; several economists defend the original study, and GiveWell keeps recommending deworming as a worthwhile bet. A ten-year follow-up (2016) reports gains in later earnings.
2017–2022	Maturity at scale	Kanika Bahl becomes Evidence Action's CEO in 2017, the year programs supported by the initiative treat over 280 million children. In 2019, Pakistan holds its first school deworming day with the initiative's support, the initiative ends its work in Vietnam and Ethiopia, Kremer and co-founder Esther Duflo share the Nobel Memorial Prize in Economic Sciences, and Cochrane's update upholds its 2015 conclusions. When COVID-19 closes schools in 2020, Kenya cancels the rest of the year's treatment and India switches to door-to-door deworming. A twenty-year follow-up (2021) reports higher consumption and earnings. In August 2022, GiveWell drops the initiative from its top charities list as part of a change in criteria, while continuing to fund it.
2023–onwards	Falling worm prevalence and planned exits	With prevalence sharply down in Kenya and several Indian states, the initiative plans exits from Kenya and Pakistan, scales back in some Indian states, and launches programs in Malawi (2024) and Tanzania (2026). A 2023 study links the original Kenya deworming to lower child mortality in the next generation. In 2025 the initiative supports campaigns reaching about 183 million children in five countries, even as aid for neglected tropical diseases contracts sharply. A GiveWell lookback published in January 2026 finds coverage gains in India but unresolved discrepancies between Evidence Action's data and government data, and a May 2026 assessment in Nigeria's Cross River State reports steep falls in worm prevalence.

Full timeline

Year (Month and date)	Event type	Details
1910	Background	Oil magnate John D. Rockefeller donates $1 million to form the Rockefeller Sanitary Commission for the Eradication of Hookworm Disease, after American doctor Charles W. Stiles had recognized hookworm symptoms among Southerners. Surveying more than 600 counties across eleven southern states, the commission finds about 40% of school-age children infected. Over the next five years its traveling dispensaries treat more than 400,000 people with deworming medicine free of charge, while education campaigns teach doctors, teachers, and the public to recognize the disease and to use sanitary privies. Follow-up surveys show the region's infection rate falling by more than half, and state health boards and the Rockefeller Foundation's International Health Board carry the work on. Nearly a century later, the campaign would become a natural experiment for estimating the long-run economic effects of deworming, cited by Deworm the World's founders and by GiveWell as part of the case for mass treatment.
1990	Research	Donald Bundy and colleagues report on a school-targeted deworming program covering the whole population (about 11,500 people) of the Caribbean island of Montserrat. All children aged 2 to 15, about 2,500, receive single-dose albendazole in four cycles four months apart, with coverage above 90% in each cycle. Surveys after 7 and 15 months show lower prevalence and intensity of roundworm and whipworm infection among the treated children, and also among people aged 16 to 25, even though fewer than 4% of adults were treated. The authors conclude that treatment aimed only at children can run through existing health services and reduce infection across a whole community. The study is an early sign of the spillover benefits to untreated people that the 1998 Kenya trial would set out to measure; in 2015, Ahuja and colleagues would cite it as evidence that mass deworming generates large externalities. Bundy, later at the World Bank, would help supervise Delhi's 2011 school worm survey.
1998	Background	The Primary School Deworming Project (PSDP) begins in Busia, western Kenya. Mass treatment for intestinal worms is phased into 75 schools in three groups of 25, rather than randomized across individual children, so that spillover effects on untreated children can be measured. Kremer and Miguel would evaluate the project through 2001, and their findings would become the founding evidence for Deworm the World.
2001	Background	World Health Assembly Resolution 54.19 sets endemic countries the target of ensuring that at least 75% of school-age children at risk of worm-related illness receive regular treatment by 2010. The target would frame the case for the government school-based programs that Deworm the World later supports; planning documents for the 2011 Bihar program in India cite it.
2004 (January)	Research	Miguel and Kremer publish "Worms: Identifying Impacts on Education and Health in the Presence of Treatment Externalities" in Econometrica (vol. 72, no. 1, pp. 159–217), reporting results from the PSDP. They find that school-based mass deworming reduces absenteeism in treatment schools by one quarter, far more cheaply than other ways of raising school participation, and that untreated children in treatment and neighboring schools also benefit, by enough to justify fully subsidizing treatment. They find no evidence of improved test scores. The paper would become the best-known randomized trial of deworming and, in 2015, the subject of high-profile reanalyses.
2007	Research	Economist Hoyt Bleakley publishes "Disease and Development: Evidence from Hookworm Eradication in the American South" in the Quarterly Journal of Economics (vol. 122, no. 1, pp. 73–117). Comparing areas by their hookworm infection rates before the Rockefeller Sanitary Commission's campaign of about 1910–1915, he finds that more heavily infected areas saw larger gains in school enrollment, attendance, and literacy afterward, with no comparable effect on adults, who had been far less infected. He estimates that an infected child was about 20 percentage points less likely to be enrolled in school, that hookworm explains around half of the South's human-capital gap with the rest of the country, and that cohorts exposed to eradication as children went on to earn substantially more as adults. Because it is not a randomized trial, the study would be left out of the 2015 Cochrane review, but Hicks, Kremer, and Miguel would cite it as part of the best evidence on deworming's long-run effects, and GiveWell would call it a high-quality study finding especially large income gains.
2007	Organizational	At the World Economic Forum Annual Meeting in Davos, Switzerland, Kremer and Duflo present evidence on school-based deworming to the Young Global Leaders Education Task Force. In response, Deworm the World is launched to coordinate technical assistance and advocacy for large-scale, government-run school-based deworming. Its founders include Kremer, Duflo, development economist Rachel Glennerster, and MIT economist Kristin Forbes, then a member of the Forum of Young Global Leaders. Kremer, Duflo, and Forbes urge fellow Young Global Leaders to join them in "deworming the world", which they pitch as a low-cost effort that could improve the lives of hundreds of millions of children. From the start, the Partnership for Child Development and Innovations for Poverty Action support Deworm the World technically and administratively, and the partnership's executive director, parasitologist Lesley Drake, is seconded to lead it. Imperial College London, which hosts the partnership, would later describe her as the initiative's founder, while the founding accounts from Innovations for Poverty Action, MIT, and Kremer and Zwane name only the economists.
2007 (August)	Research	Kremer and Miguel publish "The Illusion of Sustainability" in the Quarterly Journal of Economics (vol. 122, no. 3, pp. 1007–1065), using the Kenya deworming program to test donors' push to replace subsidies with "sustainable" community provision. From 2001, a randomly chosen set of schools in the program charged families for deworming, about $0.30 per child, roughly a fifth of the cost of drugs and delivery; this cost-sharing cut take-up by 80%, from 75% to 19%, and children with moderate or heavy infections were no more likely to pay. Health education did not change behavior, and a community mobilization effort failed. People were also less likely to take deworming drugs when their social contacts had been exposed to the program. The authors conclude that, at least in this context, a one-time intervention is unlikely to generate sustainable voluntary provision of a public good such as deworming. Ahuja and colleagues would later make the finding a central part of their 2015 argument that governments should fully subsidize deworming.
2008	Organizational	Deworm the World is incorporated as a nonprofit organization. Some later accounts, including a 2019 post by Evidence Action CEO Kanika Bahl, date the co-founding of the initiative by Kremer and Duflo to 2008, while most sources give 2007, the year of the Davos launch. Its first large activity is a Clinton Global Initiative commitment, made with several organizations and governments, to fill gaps in deworming drug supplies. Finding that some programs still stall even with drugs or funding in place, it would shift to on-the-ground technical assistance and capacity building. At the January 2008 World Economic Forum meeting in Davos, Cherie Blair, wife of former British prime minister Tony Blair, dresses up as a worm and chases delegates pretending to be children, a stunt inspired by Deworm the World.
2009 (January 31)	Expansion	At the World Economic Forum Annual Meeting in Davos-Klosters, the Deworm the World Task Force of the Forum of Young Global Leaders, which launched the initiative in 2007, announces the expansion of deworming programs in Kenya, Guyana, India, and 12 other countries. World Food Programme executive director Josette Sheeran announces a partnership to treat an additional 2 million children in 12 more countries through WFP-assisted school feeding programs. Guyanese President Bharrat Jagdeo, himself a Young Global Leader, commits to treating all of Guyana's school-age children in 2009, and Vikram Akula, founder of SKS Microfinance, pledges his company's distribution network to deworm 1 million children in a pilot. Kremer calls mass school deworming, at under 50 cents per child per year, "the most cost effective way to increase school participation of any approach rigorously tested". A short call-to-action film produced by Cinépolis chief executive Alejandro Ramírez, a founding member of the task force, and directed by Eugenio Polgovsky premieres at the event on January 30. The task force says further programs could raise worldwide deworming coverage from 10% to 30% over three years, once funding for shipping and training is found.
2009 (January)	Program launch	Kenya's then-Prime Minister Raila Odinga announces the start of the National School-Based Deworming Programme at the World Economic Forum Annual Meeting, scaling up deworming to treat 3 million of the country's children. Funds had been allocated for the 2008–09 fiscal year, but with no movement by December 2008 and the money due to expire in June 2009, Deworm the World offered to help plan, budget, and run the program. Guided by a National School Health Policy launched the same year, the program targets all 22,000 public primary schools in the country, with financial support from the Ministry of Education and technical support and drugs from Deworm the World and the Partnership for Child Development. The Kenya Medical Research Institute carries out extensive mapping of infections, and the program builds on earlier pilot school health programs in Kenya. The first round treats over 3.6 million school-age children.
2009 (April 7)	Organizational	Deworm the World moves its headquarters (its secretariat) from London to the Washington, D.C. offices of the American Institutes for Research (AIR), a research organization that had committed to support it at the 2008 annual meeting of the Clinton Global Initiative. AIR, one of its key technical and implementation partners, hosts a welcome reception at which executive director Lesley Drake presents a new twelve-minute video serving as Deworm the World's "call to global action". Drake says the two organizations are working to give countries accurate information, high-quality national plans for school-based deworming, and up-to-date training materials. At this stage, Deworm the World describes its role as helping governments build large-scale, sustainable programs led by the education sector, and expects to treat at least 10 million children by September 2009. Its partners include Feed the Children, the World Food Programme, the World Bank, the Partnership for Child Development, J-PAL, Innovations for Poverty Action, Save the Children, Imperial College London, and Right To Play.
2009	Expansion	Deworm the World begins working in India: it encourages state governments to adopt statewide school-based deworming, designs and runs prevalence and intensity surveys, and provides technical assistance and monitoring support. The first Indian deworming round it assists is in Andhra Pradesh in 2009; Bihar, Delhi, and Rajasthan would follow. In Andhra Pradesh it helps launch a pilot, but after the first round the government hires its coordinator and Deworm the World steps back; its mapping finds district prevalence of up to 21%, lower than predicted. GiveWell would later note that, apart from Punjab, Deworm the World played a role in every Indian state running a school-based deworming program as of 2013, even though India's central government already mandated and funded school-based deworming in all states.
2009	Expansion	Deworm the World holds a stakeholder meeting with The Gambia, Liberia, and Sierra Leone to help plan and write proposals for school-based deworming. It finds that Sierra Leone could reach national coverage with more donated drugs and helps source them. In the Gambia it conducts prevalence mapping and helps prepare a five-year strategy. In Liberia, at the government's invitation, it helps prepare an operational plan for neglected tropical diseases, develops training and monitoring materials, and trains master trainers, working with the Schistosomiasis Control Initiative and other partners toward a single national program. As of April 2012, Liberia remains one of its active programs, although it faces funding gaps there.
2010 (May–June)	Research	Bihar's government plans in 2009 a statewide, evidence-based school deworming program with technical support from Deworm the World, financed through two central government flagship programs, the National Rural Health Mission and Sarva Shiksha Abhiyan. In 2010, J-PAL hosts a conference with the Bihar government to share evidence on school deworming, at which Deworm the World brings in Andhra Pradesh's permanent secretary of health to speak. With no previous data on worm infections in the state, Deworm the World, the Partnership for Child Development, and AIIMS run baseline school surveys in six districts in two phases, May–June 2010 and January–February 2011, covering 3,238 children in 60 schools. Where laboratories are lacking, they use the quicker Mini Parasep SF test alongside the standard Kato-Katz method. They find 42% overall prevalence (10% to 96% across schools, 23% to 80% across districts): every surveyed district exceeds the WHO threshold for annual treatment and four of six that for twice-yearly treatment, and a predictive map built from the results shows most districts above 50%. GiveWell, summarizing Deworm the World's 2010 and 2011 Bihar surveys, would report a higher figure of 67.5%.
2010	Expansion	In Nigeria, Deworm the World helps the government collate and map existing data on worm prevalence, feeding it into the open-access mapping site thiswormyworld.org. Based on the results, the government proposes starting in Ogun State and asks for the initiative's support; as of April 2012, Deworm the World plans to stay with Ogun and see how funding develops. Its support for treatment in Nigeria would expand from 2016, and by 2021 deworming it supports would reach 4.8 million children across four states.
2010	Organizational	Innovations for Poverty Action begins incubating Deworm the World; by IPA's account the arrangement lasts from 2010 to 2014, overlapping with Evidence Action's takeover of the initiative's management in 2013. Deworm the World's managing director would explain in 2012 that it is more cost-effective to run as an initiative of IPA, which already has administration, finance, and human resources functions and works in 48 countries, than to register as a separate organization in each country where it hires staff. IPA had given start-up support, both financial and in-kind, in 2008–09, but would provide no further funding after 2009. The move follows the period in which Deworm the World's secretariat was hosted by the American Institutes for Research in Washington.
2011 (February–April)	Program launch	The Indian state of Bihar carries out its first statewide school-based deworming program, led by the Bihar Education Project Council and the State Health Society Bihar, with Deworm the World providing technical coordination and monitoring. Surveys had found worm infection rates above 50% in most districts. Teachers give deworming tablets to over 17 million children in more than 67,000 government schools, over 80% of a target population of nearly 21 million. Announcing the results in October 2011, Deworm the World (which by then has helped reach over 37 million children in 27 countries) calls it the largest school-based deworming program in the world to date. Bihar would continue the program in annual rounds; the fourth, in February 2015, treats 18.7 million children. Deworm the World's partner, the Partnership for Child Development, would later describe itself as having supported Bihar's government to deworm the 17 million children "in six months", and credit its model with growing into an Indian national program deworming 220 million children a year by 2018.
2011	Funding	Kenya's national school-based deworming program, with technical support from Deworm the World, receives five years of funding from the Children's Investment Fund Foundation (CIFF) and is relaunched. In 2012, an estimated 4.6 million school children receive treatment, and the program would go on to consistently treat over six million children per year. Evidence Action dates its support of Kenya's national program from 2012. In 2013, GiveWell notes that the Kenya program is fully funded by CIFF and the END Fund through 2016, and focuses its review on India instead.
2011 (March)	Evaluation	GiveWell, the charity evaluator, publishes its first review of Deworm the World, at the time a program hosted by Innovations for Poverty Action. Further reviews follow in November 2012 and November 2013; the initiative would become a GiveWell top charity in December 2013.
2011	Research	A prevalence survey of 3,251 children under 18 in Delhi compares worm infection across Delhi government schools, municipal schools, and 48 slums. It is run from Meerabai Polytechnic College, with 20% of samples rechecked at the All India Institute of Medical Sciences (AIIMS), under the supervision of experts including Sarman Singh of AIIMS, Lesley Drake of Imperial College London, and Donald Bundy of the World Bank. Average prevalence is 16.09%, mostly roundworm (11.84%), with the heaviest roundworm and whipworm loads among slum children who have dropped out of school or never attended, a group that includes 525 preschool children. Presented at a World Bank meeting in Washington on November 17, 2012, the study concludes that out-of-school and under-five children form a reservoir of infection that school-based programs would miss, so that programs need several delivery platforms. India's National Deworming Day, from 2015, would target children aged 1 to 19 at both schools and anganwadis (preschools). The study remains unpublished as of 2023.
2012 (January 30)	Background	At the Royal College of Physicians in London, 13 pharmaceutical companies, the U.S., U.K., and U.A.E. governments, the Bill & Melinda Gates Foundation, the World Bank, and other partners endorse the London Declaration on Neglected Tropical Diseases, a coordinated push to eliminate or control ten neglected tropical diseases, including soil-transmitted worms and schistosomiasis, by 2020 in line with a new WHO roadmap. Drug makers pledge to sustain or expand their donations to 2020: GlaxoSmithKline will donate 400 million albendazole tablets a year for soil-transmitted worms, Johnson & Johnson 200 million mebendazole tablets a year, and Merck KGaA will raise its praziquantel donation for schistosomiasis from 25 million to 250 million tablets a year. Partners also commit more than $785 million, including a five-year, $363 million Gates Foundation commitment and an $89 million U.S. appropriation for USAID's work on these diseases. The donations would change how government programs supported by Deworm the World get their drugs: Bihar, which first bought albendazole itself, would later receive it from the WHO donation.
2012 (February 21)	Program launch	Delhi holds its first statewide school and anganwadi deworming day, launched the day before by Chief Minister Sheila Dikshit, who gives tablets to 50 children at her residence and says deworming will be held twice a year. Run under the state's Chacha Nehru Sehat Yojana school health scheme by a committee joining the health, education, and women and child development departments with the municipal bodies, the program receives technical assistance from Deworm the World and Global Health Strategies, funded by the Michael & Susan Dell Foundation, while Feed the Children donates the mebendazole through the Clinton Global Initiative commitment. Teachers and anganwadi workers treat about 2.65 million children in some 2,400 schools and 8,200 anganwadis by the February 27 mop-up day, against a target of 3.6 million, although about a fifth of targeted schools had not reported by December. Deworm the World's report notes problems found by monitors, such as sick children given tablets in 21% of observed schools, and says Rajasthan became interested in deworming after seeing Delhi's program.
2012 (April 23)	Evaluation	In a phone conversation with GiveWell co-founder Holden Karnofsky and Stephanie Wykstra, Deworm the World managing director Alissa Fishbane describes an initiative working in Kenya, Liberia, Ogun State in Nigeria, and the Indian states of Bihar, Delhi, and Rajasthan, on a budget of just over $1 million in 2011. She explains that it runs as an initiative of Innovations for Poverty Action to keep administrative costs low, although IPA has given it no funding since start-up support in 2008–09. Governments invite it in, often after advocacy with the World Bank and J-PAL; Rajasthan asked for help after hearing of Delhi's program. Fishbane says governments would not have paid for its activities and some programs would not have happened at all, and that it has turned down one country where prevalence was too low. Asked about relying on high-prevalence studies when Delhi averages 16–17%, she argues deworming is cost-effective anywhere above WHO guidelines and cites economist Owen Ozier's research on large cognitive gains in very young children. GiveWell asks to go through "the nuts and bolts of who gets paid to do what" in a later conversation.
2012 (July 18)	Debate	The PLOS Medicine blog Speaking of Medicine hosts a debate, "Should Deworming Policies in the Developing World be Reconsidered?", following the July 2012 update of the Cochrane review by David Taylor-Robinson and colleagues. Paul Garner, a review author and coordinating editor of the Cochrane Infectious Diseases Group at the Liverpool School of Tropical Medicine, argues that deworming is being sold as a wonder cure for poverty, but that in studies treating all schoolchildren, effects on weight, haemoglobin, cognition, school attendance, and performance are absent, small, or not statistically significant. He also flags unpublished trials, including a completed 2006 Vietnam school trial and a 1 million-child mortality trial in India (DEVTA), as a challenge to scientific integrity. In reply, Peter Hotez, Neeraj Mistry, and Alan Fenwick, director of Imperial College London's schistosomiasis control program, call the review sound but argue that it may "stack the deck" by grouping different worm species and drugs, and by diluting effects across lightly infected children, since only moderate and heavy infections typically cause measurable disease. They urge that deworming remain a cornerstone of integrated neglected tropical disease control.
2012 (November 2)	Funding	In a conversation with GiveWell co-founder Elie Hassenfeld, Deworm the World managing director Alissa Fishbane says the organization has raised funds for all its 2013 work except Bihar, where it faces a gap of $695,000: $415,000 to support the program for 21 million school-age children, $150,000 for a follow-up parasitological survey, and $130,000 to extend deworming to Bihar's 6 million preschoolers. A second Bihar round has just taken place in September 2012, and rounds have recently started in Delhi and Rajasthan. Fishbane explains that donors find the program "too hot" or "too cold" for various reasons, that individual website donations bring in only about $150,000 a year, and that the 2012 Bihar gap was closed partly through the World Economic Forum's Young Global Leaders. She notes the organization has no follow-up parasitological data yet, relying instead on statistically representative coverage checks designed with the Abdul Latif Jameel Poverty Action Lab (J-PAL). CIFF, which funds the Kenya program, is exploring longer-term support for Bihar; it would go on to fund Evidence Action's technical assistance for Bihar's fourth round in 2015. GiveWell would name the initiative a top charity in December 2013.
2012	Funding	Deworm the World receives a five-year, $5.23 million grant from the United States Agency for International Development (USAID) to support its work in India, earmarked for expansion into new states. Based on past costs of $220,000 to $483,000 per state, GiveWell would estimate that the funds the initiative expects for state scale-up in 2014 could take it into four to six more Indian states.
2013 (January 2)	Debate	The BMJ publishes "Deworming debunked", a feature by freelance journalist Nigel Hawkes arguing that while deworming undoubtedly improves child health, claims for its wider benefits on growth, brain power, education, and employment are often equivocal. Hawkes lists the many organizations backing deworming as a development intervention, including the World Bank, the WHO, the Gates Foundation, the Copenhagen Consensus, Innovations for Poverty Action, J-PAL, and Deworm the World itself, and contrasts them with the 2012 revision of the Cochrane review by a team from the Liverpool School of Tropical Medicine, which found the evidence for those wider benefits missing. The article signals that the evidence dispute is already public more than two years before the "worm wars" of 2015: the replication authors of that year cite it as background, and Ahuja and colleagues cite it as an example of those challenging mass school deworming as a policy priority.
2013 (April 27)	Research	The Lancet publishes the albendazole results of DEVTA, a cluster-randomized trial led by Lucknow-based professor Shally Awasthi and Oxford epidemiologist Richard Peto in Uttar Pradesh, covering about 1 million preschool children served by 8,338 anganwadi child-care centres in 72 rural blocks. From 1999 to 2004, children aged 6 to 72 months in half the blocks receive albendazole every six months from anganwadi workers, with 86% compliance, at a delivery cost of about $0.10 per child. Treatment halves worm egg prevalence (16% versus 36%, mostly light infections) but has no significant effect on weight (0.04 kg difference) or on child mortality (risk ratio 0.95, 95% confidence interval 0.89–1.02) across some 25,000 recorded child deaths. The authors conclude that existing village staff can deliver such programs cheaply and sustainably, but that regular deworming had little effect in this lightly infected population and that mortality reduction is unlikely to be a main aim of deworming programs. The 2015 Cochrane update would add DEVTA to its evidence base, and Uttar Pradesh would later become one of the Indian states where Deworm the World works directly.
2013 (August 23)	Organizational	Innovations for Poverty Action announces the launch of Evidence Action, a new nonprofit created with its support to take cost-effective, evidence-based programs to scale in Africa and Asia. Two IPA initiatives spin off to be managed by it: the Deworm the World Initiative and Dispensers for Safe Water, a chlorine dispenser program. Alix Zwane, who joins from the Bill & Melinda Gates Foundation, becomes executive director. At the time, the Deworm the World Initiative reports having reached more than 40 million children by partnering with governments.
2013 (November)	Evaluation	GiveWell publishes the review behind its December 2013 top-charity recommendation. It finds that Deworm the World has been involved in all but one statewide school deworming program running in India and probably raises the chance that states go ahead, citing Rajasthan officials and Devesh Kapur, an expert recommended by the Center for Global Development, although one official says the help was not needed. It estimates that the four Indian rounds reviewed cost about $0.35 per child in total, with Deworm the World paying under 10%, and puts its leverage anywhere from under 1x to 4–5x. GiveWell cautions that infections in India are much lighter than in the Kenya trial behind the evidence, with no schistosomiasis; that India's lymphatic filariasis program already gives the same drug in some areas; that coverage figures and monitor reports are of uncertain reliability; and that the initiative's self-evaluation is less rigorous than other top charities'. It credits Evidence Action's new executive director Alix Zwane with far clearer communication than in earlier dealings, and notes that Punjab started deworming on its own after Deworm the World lacked funds to assist it.
2013 (December)	Evaluation	GiveWell names the Deworm the World Initiative, led by Evidence Action, one of its three top charities for the 2013 giving season, alongside GiveDirectly and the Schistosomiasis Control Initiative (SCI). The new listing coincides with GiveWell dropping the Against Malaria Foundation, its top recommendation for the previous two years, over room-for-more-funding concerns. GiveWell's stated best guess is that the program is somewhat less cost-effective than SCI's, because worm infections are less prevalent and less intense where it works. Good Ventures, then partnered with GiveWell, follows with a $1.5 million unrestricted grant to Evidence Action intended for the initiative's work with Indian state governments. The initiative would remain a GiveWell top charity until August 2022.
2014 (June)	Expansion	Deworm the World signs a memorandum of understanding with Madhya Pradesh's Public Health and Family Welfare Department to create a school-based deworming program for the state's school-age children, director Grace Hollister tells GiveWell in a June 24 conversation. She reports that, after India's 2014 national elections, deworming has been proposed for the new government's 100-day agenda, and that Deworm the World is working with Ajay Khera, head of the health ministry's Child Health Division, and offering help with planning and guidelines; India's first National Deworming Day would follow in February 2015. A repeat survey in Rajasthan finds almost no hookworm but about 20% roundworm prevalence, so annual treatment continues there, and Deworm the World is exploring a statewide program in Jharkhand with USAID support. CIFF, interested in funding its national work and expansion into new states from late 2014, was among donors who pledged $120 million for deworming at an April 2014 Uniting to Combat Neglected Tropical Diseases conference, including $50 million each from CIFF and the Gates Foundation over five years.
2014	Expansion	Deworm the World begins a partnership with the government of Vietnam, a country with a high worm burden, to strengthen the delivery, reach, and monitoring of its existing school-based deworming program, working with Thrive Networks (known in Vietnam as East Meets West Foundation) in four provinces, with funding from Dubai Cares. Unusually for the initiative, the government has already been running school deworming at scale for several years, so the aim is to improve an existing program rather than build a new one. The partnership would end in 2019, according to Evidence Action (J-PAL gives 2020).
2014 (November 21)	Funding	GiveWell reports that the Deworm the World Initiative has received about $2.3 million as a result of its recommendation since December 2013, largely allocated as GiveWell expected, with $881,000 held as reserves. The initiative seeks a further $1.3 million for 2015 and 2016. The update also notes about $1.6 million from CIFF and the Gates Foundation to the initiative and the London School of Hygiene & Tropical Medicine for research on whether transmission of soil-transmitted worms can feasibly be broken. GiveWell keeps the initiative on its top charities list in its update the following month.
2014 (December 18)	Strategy	In an article for the World Economic Forum, Kremer (now Gates Professor of Developing Societies at Harvard University) and Evidence Action executive director Alix Zwane take stock of Deworm the World. They report that it now treats 35 million children globally: in the past school year, Kenya's national program treated 6.4 million children, surpassing its goals, and the Indian states of Delhi, Bihar, and Rajasthan treated 29 million, with Madhya Pradesh also committed to large-scale school deworming. Yet only about 32% of the world's 870 million at-risk school-age children (270 million) were treated in 2013, far short of the WHO's 75% goal. Over 400 million untreated at-risk children live in ten countries, nine of which urgently need to scale up: India, Nigeria, Indonesia, Ethiopia, the Philippines, Pakistan, the Democratic Republic of the Congo, Tanzania, and South Sudan. Evidence Action plans to grow the initiative "exponentially", with partners including the END Fund, the Gates Foundation, Dubai Cares, the World Bank, LSHTM, and CIFF. By 2019, the initiative would support programs in four of the nine: India, Ethiopia, Nigeria, and Pakistan.
2015 (February 10)	Program launch	India's Ministry of Health and Family Welfare holds the country's first National Deworming Day, launched by Union Health Minister Jagat Prakash Nadda. It is a fixed-day effort to deworm children at schools and anganwadis (preschools) in eleven states, from Assam to Tamil Nadu, with an initial target of 140 million children. Evidence Action's Deworm the World Initiative, which already helps state programs in Delhi, Bihar, Rajasthan, and Madhya Pradesh deworm 30 million children a year, provides technical assistance, funded by CIFF, Dubai Cares, USAID, and other donors; the day before, Dubai Cares announces a US$3 million, four-year contribution to support that work, including national guidelines, prevalence surveys, and state scale-up. About 89 million children are treated, the largest one-day deworming program to date. In October 2015, India reports 89.9 million children treated in 11 states since the launch. From 2016, National Deworming Day would cover all 36 states and union territories and later be held twice a year, on 10 February and 10 August.
2015	Expansion	Ethiopia launches a national school-based deworming program, incorporating practices from India and Kenya, with support from Deworm the World and the Schistosomiasis Control Initiative. Deworm the World had begun advising the Ethiopian government in late 2014, after Ethiopian officials visited Kenya on a learning exchange and met its representatives during the trip. The program aims to deliver more than 100 million treatments in all endemic areas by 2020.
2015 (May)	Research	Amrita Ahuja, Sarah Baird, Joan Hamory Hicks, Kremer, Miguel, and Shawn Powers circulate "When Should Governments Subsidize Health? The Case of Mass Deworming" as an NBER working paper, later published in the World Bank Economic Review. Reviewing studies that account for spillovers, from the Rockefeller hookworm campaign in the American South to cluster-randomized programs in Kenya and Uganda, they find consistent short-run gains in school participation and long-run gains in test scores, employment, and income. In Kenya, charging families about $0.30 per child cut take-up from 75% to 19%, suggesting most parents will not pay for treatment that is not fully subsidized, and the long-run earnings gains imply future tax revenue that may exceed the program's cost. They estimate that screening children before treating them would cost more than six times as much per infection treated as mass treatment, and that treating most of the 870 million at-risk children would cost about $300 million a year by mass treatment versus about $2 billion by screening. They conclude deworming would pay off even if its benefits were a fraction of those estimated. Ahuja discloses that she chairs Evidence Action's board, unpaid.
2015 (July 2)	Organizational	Harvard Magazine profiles Evidence Action, two years after its founding, as an organization "committed to translating research-based evidence into cost-effective action". Executive director Alix Zwane says it exists to close "a gap between what research shows is effective in global development and what is implemented in practice". The profile reports that Deworm the World, incubated by Innovations for Poverty Action and taken over by Evidence Action to reach scale, has already reached about 165 million children during 2015 and has twice been named a GiveWell top charity. Among those quoted is board member Kanika Bahl, then a managing director at the Results for Development Institute, who argues that development funding should follow evidence of value rather than political trends or funder interests; she would become Evidence Action's chief executive in February 2017.
2015 (July 22)	Debate	Alongside the two reanalyses, the International Journal of Epidemiology publishes a commentary by the authors of the original Kenya trial, Joan Hamory Hicks, Kremer, and Miguel. They thank the replication teams and accept that the "pure replication" corrects some errors in their 2004 paper, but read it as strongly supporting its findings: set side by side, the original and updated estimates are "extremely similar", with significant direct effects on infections and school participation, spillovers to untreated pupils in treated schools, and spillovers to schools up to 3 km away. They argue that the updated within-school spillover evidence keeps valid the original paper's key conclusion that individually randomized trials underestimate the true impact of deworming. The replication authors reply in a letter, and the same journal carries Shah Ebrahim's "Worm wars, data resources and vitamin D".
2015 (July 22)	Debate	In a BuzzFeed essay, researcher Ben Goldacre, who has worked on and off at the London School of Hygiene & Tropical Medicine since 2009, uses the "worm wars" to argue for sharing research data. Summarizing the reanalysis of Miguel and Kremer's Kenya trial, he reports that age is missing for 21% of children, that most of the paper's ten results tables contain errors, that 11 findings have mislabelled statistical significance (a reported anemia reduction has a p value of 0.194), and that a coding error had excluded most schools from the "deworming nearby" category, so that correcting it effectively eliminates the benefit for neighbouring schools. Yet he calls the trial excellent research that helped spread randomized trials across development work, and praises Miguel and Kremer for handing over their data. He contrasts this with DEVTA, the Indian deworming and vitamin A trial led by Awasthi and Peto, whose results took seven years to publish, a delay he attributes to its tight budget rather than malice. Goldacre says he has no position on the worm wars and that Peto is a social acquaintance.
2015 (July 22–23)	Debate	The International Journal of Epidemiology publishes two reanalyses of Miguel and Kremer's Kenya trial by epidemiologists at the London School of Hygiene & Tropical Medicine, carried out under a replication program of the International Initiative for Impact Evaluation (3ie) using data the original authors shared. The "pure replication" by Alexander Aiken and colleagues finds similar reductions in worm infections and largely unchanged effects within treated schools, but a coding error that substantially changes estimated spillovers to nearby schools. The second, by Calum Davey and colleagues, applies epidemiological methods and notes missing data, lack of blinding, and other interventions in some schools. An updated Cochrane systematic review led by David Taylor-Robinson, released the same week, concludes there is substantial evidence that routine school deworming does not improve average nutritional status, haemoglobin, cognition, school performance, or survival, with mixed, bias-prone evidence on attendance. The dispute would become known as the "worm wars".
2015 (July 23)	Debate	Evidence Action responds to the reanalyses and the Cochrane review with "Worms Win, Kids Lose? Our Statement". It argues that the case for mass school deworming stands on two legs: rigorous evidence that it is cost-effective, and the fact that treating every child without testing is cheap, safe, and efficient. Following the original statistical strategy, it says, the "pure replication" finds a few errors but the same fundamental result, that deworming increases school attendance. It calls the statistical replication's choices, such as splitting the data into smaller subsamples and counting children before treatment began as treated, poor practice that weakens the result, describing the outcome as a "manufactured controversy" that could threaten real programs, and suggests replicators face incentives to generate controversy. It also rejects the Cochrane review's suggestion that children be tested before treatment, arguing that tests are expensive while the medicine is cheap and harmless to uninfected children, and that presumptive treatment reaches the most sick children with limited money.
2015 (July 24)	Debate	As the published reanalyses of the Kenya trial draw heavy attention on Twitter, with Ben Goldacre writing about them for BuzzFeed, World Bank lead economist Berk Özler updates a review he first posted on the bank's Development Impact blog six months earlier, when the papers appeared on 3ie's website. He argues that the statistical replication's key departures from the original study (redefining treatment by calendar year, so that some untreated schools count as treated; analyzing each year separately; weighting every school equally regardless of size; and ignoring spillovers between schools) are jointly needed to make the attendance effects disappear. Comparing only schools treated in both years with schools untreated in both, using a table supplied by Joan Hamory Hicks, he reports effects on school participation of about 6 percentage points, close to the original 7. He concludes that, if anything, he finds the original study more robust than before, while warning that replications that try many analytic choices risk false negatives. Özler discloses that his long-time partner is economist Sarah Baird, a co-author of the long-term follow-ups.
2015 (August 3)	Debate	Paul Gertler, a professor at UC Berkeley's business and public health schools and in the early 2000s chief economist for human development at the World Bank, publishes "Good Science Gone Wrong?" on the Berkeley Blog in defense of Miguel and Kremer's Kenya study. He accepts that the "pure replication" confirms the effect on school attendance, but argues that the statistical reanalysis makes the effect disappear only by "torturing the data": redefining how treatment was assigned, reweighting the absenteeism measures, and splitting the sample into subgroups, a "fishing exercise" he says most academics would reject. He questions the authors' choice of the International Journal of Epidemiology, whose editor-in-chief works in their department, and criticizes journalists for reporting deworming as "debunked" without contacting the original authors or weighing other studies. He notes that Miguel and Kremer had shared their data and code since January 2007 and had then acknowledged a coding error that overstated benefits to nearby untreated children. Gertler discloses that he works at the same university as one of the original authors and formerly chaired the board of 3ie, which funded the replication, though not when it decided to do so.
2015 (August 6)	Debate	Esther Duflo and Dean Karlan, who helped found J-PAL and Innovations for Poverty Action (Karlan is IPA's president), publish "Deworming: An Informed Debate Requires a Careful Look at the Data". They note that the "pure replication" confirms the 2004 study's main conclusion that school-based deworming increases school participation, while the statistical reanalysis uses different assumptions that Kremer, Miguel, and other experts (including Berk Özler and J-PAL and IPA affiliates Chris Blattman and Paul Gertler) contest. Quoting Gertler that "replications should be held to the same standards as any other study", they call it premature to treat the original conclusions as invalid. Given how involved J-PAL and IPA have been in deworming research and scale-up, they call for an independent, technically focused re-appraisal of the study and its reanalysis by researchers outside their networks, which 3ie offers to keep supporting, and for further randomized evaluations of school deworming in other countries. Noting that Evidence Action, GiveWell, and the Center for Global Development continue to back school deworming, they say IPA and J-PAL will do the same while awaiting the re-appraisal.
2015 (August 18)	Debate	Columbia University's Macartan Humphreys, who says he works in neither economics nor epidemiology, posts "What Has Been Learned from the Deworming Replications: A Nonpartisan View", reworking Miguel and Kremer's posted data and code. He finds both teams agree that, with corrected data and the original method, the headline 7.5-point drop in absenteeism falls to just under 4 points and is not significant, evidence for spillovers weakens, and the anemia link disappears. What remains is a tightly estimated direct effect on attendance, but it is clear only in the first year and barely shrinks when worm infection is controlled for, leaving open whether it works through the medication. He notes the original team had found many of the errors in 2007 without publishing errata, and that groups arguing for deworming's educational benefits, including Deworm the World, which one of the authors reportedly launched on the back of the results, rely heavily on this study. Still, he argues, a Bayesian reading can leave cheap deworming a good bet. Humphreys discloses that he co-authored a transparency article led by Miguel, a former classmate.
2015 (August)	Organizational	Alix Zwane steps down as executive director of Evidence Action to become chief executive of the Global Innovation Fund. Evidence Action hires Jeff Brown, formerly the fund's interim CEO, as executive director, while Grace Hollister remains director of the Deworm the World Initiative. GiveWell calls Zwane "a highly effective leader" whose departure risks disruptions that could change its view of the organization, though it guesses it will not. Brown's tenure would be short: board member Kanika Bahl would become acting CEO in November 2016 and CEO in February 2017.
2015 (October 22)	Debate	PLOS Neglected Tropical Diseases publishes competing viewpoints on mass deworming. In "The Case for Mass Treatment of Intestinal Helminths in Endemic Areas", Joan Hamory Hicks, Kremer, and Miguel argue that the "pure replication" of their Kenya trial confirms its three main findings, differing mainly in that spillovers reach about 3 km rather than the 6 km originally estimated because of a coding error. They criticize the second reanalysis and the Cochrane review for splitting the two-year trial into separate years, weighting schools equally, and ignoring spillovers, and report that comparing only schools treated in both years with schools untreated in both still shows a 5.94-percentage-point rise in school participation. They note that the Cochrane review leaves out long-run studies, including Ozier's work on younger siblings, a Uganda follow-up, "Worms at Work", and research on hookworm eradication in the American South, and conclude that mass deworming should remain a policy priority in endemic regions. Epidemiologist Judd Walson replies that the evidence does not uniformly show benefit and at best suggests modest effects among children with documented infections, noting that treating all children carries real costs for governments and donors.
2015 (November 18)	Funding	In its giving season update, GiveWell ranks Deworm the World's $7.6 million "capacity-relevant" funding gap at the top of its priorities, tied with the Against Malaria Foundation, and recommends that Good Ventures grant the initiative $10.8 million, out of about $44.4 million for its top charities. It estimates Deworm the World-associated programs at about 10 times as cost-effective as cash transfers, and wants the initiative to show it can work beyond India and Kenya: having said a year earlier that it could not use much additional funding, Deworm the World now identifies opportunities such as Punjab province in Pakistan, and plans to enter Ethiopia and Nigeria with funds it already holds. GiveWell warns that donations outside India may buy less government co-funding, and that money for Deworm the World may be fungible with Evidence Action's less cost-effective Dispensers for Safe Water program: its review estimates that about $0.8 million, roughly 70% of the GiveWell-directed funds Deworm the World received that year, led Evidence Action to shift unrestricted money to its other programs.
2015 (November 19)	Research	Lesley Drake, Sarman Singh, and colleagues from Deworm the World, the Partnership for Child Development, and the Bihar government publish a lessons-learned account of the 2011 Bihar campaign in PLOS Neglected Tropical Diseases. They describe a program that went from conception to treatment in under 12 months: a state steering committee joining the health and education departments, a cascade that trained nearly 140,000 teachers and 20,000 health staff, and community campaigns tied to the "Right to Education" drive, with only one adverse event reported. Because the campaign predated the global drug donation of the 2012 London Declaration on Neglected Tropical Diseases, Bihar bought albendazole from an Indian generic manufacturer, and it scheduled deworming six months apart from lymphatic filariasis treatment. The authors estimate that $500,000 from Deworm the World and the partnership, funded by the World Bank and the Global Network for Neglected Tropical Diseases, leveraged at least $1.56 million from Bihar's government. Later rounds reach 16.3 million children in 2012 and in 2014, now with donated drugs, and the authors present Bihar as the proof of concept for India's National Deworming Day.
2015	Impact assessment	Deworm the World's follow-up prevalence survey in Bihar's schools, carried out in early 2015 with random sampling across 14 districts to represent the whole state, finds soil-transmitted worm prevalence of 35%, against 67.5% in the 2011 baseline; hookworm falls from 42.2% to 17% and roundworm from 52.1% to 19%. Between the two surveys Bihar holds only four deworming rounds, three school-based rounds assisted by Deworm the World and one community round by the National Filaria Control Programme, rather than the twice-yearly treatment planned. In its November 2015 review, GiveWell calls the results consistent with the program reducing infections but lists alternative explanations: the baseline covered only four districts, chosen non-randomly; no district was surveyed in both rounds; lymphatic filariasis campaigns also distributed albendazole; and Bihar's inflation-adjusted income per person rose 39% over a similar four-year period. GiveWell notes that Deworm the World plans to run such follow-up surveys periodically.
2015 (July 24)	Evaluation	GiveWell responds to the reanalyses and the Cochrane review, arguing that the replications do not bear on the most important parts of its case for deworming, and that because mass deworming is so cheap, there is a good case for funding it even under substantial doubt about the evidence. GiveWell continues to recommend both SCI and the Deworm the World Initiative, a position Giving What We Can also defends.
2015 (July 30)	Debate	Economists Michael Clemens and Justin Sandefur of the Center for Global Development publish "Mapping the Worm Wars", arguing that the media were wrong to report the case for mass deworming as "debunked". They separate a "pure replication", which checks for errors, from "alternative analyses", which test legitimately disputable choices, and say only the former, by Aiken and colleagues, could overturn the original study. That replication, they argue, is competent and correct on its own terms, but its corrections show the original code measured spillovers to schools within about 4 km rather than the 6 km the paper reported, so the spillover finding survives at a somewhat different size; they compare reading it otherwise to dismissing John Snow's cholera evidence by drawing too wide a circle around the Broad Street pump. They also criticize the Cochrane review for excluding nearly all long-term studies, and conclude that the policy case for mass deworming is "largely unchanged". They disclose that their center created the working group that founded 3ie, which funded the critiques, and that Kremer and Miguel are its affiliates.
2016 (July 18)	Debate	The Journal of Biosocial Science publishes "Deworming Delusions? Mass Drug Administration in East African Schools" by Tim Allen and Melissa Parker, drawing on ethnographic fieldwork since 2005 in more than 100 villages in Uganda and Tanzania. They argue that claims for school-based deworming are over-optimistic: Miguel and Kremer's 2004 Kenya findings are flawed, collated trials show no significant overall health impact, and school registers show drug coverage usually falling below target. Kenya's national school-based program reports treating at least 6.4 million children in more than 15,000 schools in 2014, yet they note a study of 153 schools in Busia and neighbouring counties where soil-transmitted worm prevalence falls only from 34.8% in 2012 to 19.7% in 2014, with no significant change at many schools and better results where sanitation, health services, and incomes are better. They question GiveWell's estimate that deworming may be about 50 times more effective than cash transfers, and raise ethical concerns about giving tablets to children without consulting parents. Large programs, they conclude, are "underpinned less by evidence, than by a normative commitment", though treating infected children remains appropriate. Their fieldwork was funded by the Schistosomiasis Control Initiative under the auspices of the Gates Foundation.
2016 (July 26)	Evaluation	GiveWell publishes "Deworming might have huge impact, but might have close to zero impact", explaining why its recommendation of the Schistosomiasis Control Initiative and Deworm the World carries unusual risk. Most of its staff believe deworming programs are more likely than not to have little or no impact, and its cost-effectiveness model applies roughly a 1–2% multiplier to the effects found in the Kenya trial. GiveWell cites thin evidence of short-term health effects, leaving no clear mechanism for long-run gains; baseline infections in the trial roughly 4 to 5 times as high as where the two charities now work, further inflated by El Niño flooding in 1998; and the possibility that effects only appear above some infection threshold. Because deworming is so cheap, it still estimates the programs at roughly 5 to 10 times as cost-effective as cash transfers in expectation, calling them "a worthwhile bet". It expects no new long-term trial soon and considers funding one too slow and costly, but awaits 15-year follow-up data from the Kenya trial.
2016 (August)	Implementation	India holds a second National Deworming Day round for the first time in a single year, in 24 of its 36 states and union territories. After the February 10, 2016 round treated more than 179 million children, India's Ministry of Health and Family Welfare had announced in May that, based on worm mapping and prevalence data, two rounds a year would be needed in the country with the world's highest worm burden. Evidence Action, the government's technical assistance partner, supports the national government and works directly with the states of Uttar Pradesh, Chhattisgarh, Telangana, and Tripura, helping with advocacy, prevalence mapping, training and awareness materials, drug procurement planning, and monitoring. To raise coverage, including among out-of-school children, states run community campaigns with loudspeaker vehicles, folk performers, school rallies, billboards, broadcast ads, and launch events for media and politicians, while the ministry and officials promote the day on social media. Twice-yearly rounds, on February 10 and August 10, would become the program's standard schedule.
2016 (November)	Research	Sarah Baird, Joan Hamory Hicks, Kremer, and Miguel publish "Worms at Work: Long-run Impacts of a Child Health Investment" in the Quarterly Journal of Economics (vol. 131, no. 4, pp. 1637–1680; online since July 19), a ten-year follow-up of PSDP participants. Men who were eligible for deworming as boys stay in primary school longer, work 17% more hours each week, are more likely to hold manufacturing jobs, and miss one fewer meal a week; women who attended treatment schools as girls are about a quarter more likely to have attended secondary school, halving the gender gap, and shift from traditional farming toward cash crops and self-employment. The authors estimate a conservative annualized financial internal rate of return of 32%, and argue that mass deworming may generate more future government revenue than it costs in subsidies. The study finds no long-term effects on physical growth or body mass index. GiveWell's analysis of the long-term economic benefits of deworming would draw on this panel of former PSDP pupils, the Kenya Life Panel Survey.
2016	Expansion	Deworm the World begins supporting treatment in Nigeria, funded from its unrestricted funding, and supports a worm prevalence survey in Pakistan, where it had begun exploring work in 2015. GiveWell notes that as of September 2016, the initiative has supported programs in India, Kenya, Ethiopia, Vietnam, and Nigeria, with preliminary work in Pakistan and Indonesia, whereas in early 2015 it had supported treatments only in India and Kenya. In Nigeria, deworming supported by the initiative would reach 4.8 million children across four states in 2021. In Indonesia, it has begun preliminary talks with the government, which, unlike Pakistan's, has a neglected tropical disease department to coordinate with, and guesses it might support a program costing $1.6 million to $4 million; GiveWell rates this among its least certain growth opportunities.
2017 (January)	Debate	The Lancet Global Health publishes a systematic review and network meta-analysis of mass deworming by Vivian Welch, Elizabeth Ghogomu, Howard White, and colleagues, funded by the Canadian Institutes of Health Research and the WHO. Covering 52 studies of up to five years with more than 1.1 million children, plus four long-term studies 8 to 10 years after treatment with more than 160,000 children, it finds that mass treatment for soil-transmitted worms leads to little or no improvement in weight, height, stunting, short-term attention, school attendance (1% higher, a statistically insignificant difference), or mortality. Its analyses do not suggest spillover benefits for untreated children, and the evidence on long-term economic productivity, literacy, and school enrolment is rated very low certainty. Mass treatment for schistosomiasis might slightly increase weight. The authors call for individual participant data analysis to find which children, if any, benefit. In accompanying comments, Cochrane reviewers David Taylor-Robinson and Paul Garner call it a "Campbell replication" confirming "little or no effect of community deworming", while another comment concludes that "the debate persists".
2017 (February 22)	Organizational	Evidence Action's board appoints Kanika Bahl as chief executive. A board member since 2015, she has been acting CEO since November 2016. Bahl previously held a leadership role at the Clinton Health Access Initiative as it grew from 50 to 700 staff, launching work in 20 African countries and helping manage a $380 million pediatric HIV/AIDS treatment program across 33 countries, and later served on the leadership team of Results for Development. GiveWell co-founder Elie Hassenfeld calls Evidence Action "an outstanding organization". Bahl says that in four years it has worked "with governments to deliver deworming medicines for hundreds of millions of children". By 2026, Bahl would be Evidence Action's former CEO, leading the AI Access Initiative, which is incubated at Evidence Action to scale AI-enabled programs for people in poverty in low- and middle-income countries and is advised by Kremer.
2017 (June 8)	Debate	Economists Kevin Croke, Joan Hamory Hicks, Eric Hsu, Kremer, and Miguel publish a viewpoint, "Should the WHO withdraw support for mass deworming?", in PLOS Neglected Tropical Diseases. It responds to an April 2016 meeting of a World Health Organization Guidelines Development Group, after which the WHO is to announce whether it will reaffirm its long-standing recommendation of mass treatment where soil-transmitted worm prevalence exceeds 20%. Drawing on their 2016 meta-analysis, which covers twice as many trials as the 2015 Cochrane review, the authors argue that the Cochrane analysis is statistically underpowered. They estimate that mass deworming raises child weight by 0.134 kg on average (0.148 kg where prevalence exceeds 20%), with weight gain per dollar more than 35 times that of school feeding programs. Citing the ten-year "Worms at Work" follow-up, they argue that even a 1-in-100 chance of long-run benefits of that size would make deworming worth its cost, and conclude that WHO support for mass deworming remains scientifically justified. Kremer discloses that he is a former board member of Deworm the World, from which he has received no funding.
2017 (September 29)	Background	Following the review of its recommendations that began with an April 2016 Guidelines Development Group meeting, the WHO publishes its guideline "Preventive chemotherapy to control soil-transmitted helminth infections in at-risk population groups", announcing it as "WHO recommends large-scale deworming to improve children's health and nutrition". It is the first deworming guideline approved by the WHO's Guidelines Review Committee, confirming that deworming improves the health and nutrient uptake of heavily infected children. Dirk Engels, director of the WHO's neglected tropical diseases department, says there is now "global evidence-based consensus that periodic, large-scale deworming is the best way to reduce the suffering caused by intestinal worms". The guideline recommends annual or twice-yearly single-dose albendazole or mebendazole for children wherever baseline prevalence is 20% or more, using donated drugs, while the WHO stresses that sanitation, hygiene, and safe water are also needed. Its target is to treat at least 75% of the estimated 873 million children in high-prevalence areas by 2020; in 2016, 63% were treated. By reaffirming large-scale deworming, the guideline keeps in place the policy basis for the government programs that Deworm the World supports.
2017	Expansion	Programs supported by Deworm the World treat more than 280 million children during the year across India, Kenya, Ethiopia, Vietnam, and Nigeria. More than 260 million of them are treated in India through National Deworming Day, which by now targets all children aged 1 to 19 at schools and preschools.
2018 (July)	Research	Economist Owen Ozier publishes "Exploiting Externalities to Estimate the Long-Term Effects of Early Childhood Deworming" in the American Economic Journal: Applied Economics (vol. 10, no. 3, pp. 235–262). Using the spillovers from the school-based deworming in Kenya studied by Miguel and Kremer, he examines younger children who were not themselves treated. Ten years after the intervention, children who were under one year old when their communities received mass deworming show large cognitive gains, equal to between 0.5 and 0.8 years of schooling, and the effects are nearly twice as large among those whose older siblings were treated directly; he finds no effect on height or stunting. Earlier versions of the research had already entered the debate: Deworm the World's managing director cited it in 2012 to defend deworming preschool children, Kremer and Zwane described its sibling findings in their 2014 article, and a 2015 World Bank working-paper version was cited in the 2017 case against withdrawing WHO support for mass deworming.
2018 (November 15)	Expansion	Kenya's Ministry of Health pilots IDA, a triple-drug treatment for lymphatic filariasis (elephantiasis) that adds ivermectin to the standard diethylcarbamazine and albendazole, in three areas, the first IDA program in Africa. The regimen could cut the time needed to treat and break transmission from at least five years to two, and the pilot's results are to guide nationwide scale-up in 2019. Evidence Action is among the partners, alongside the END Fund, the Gates Foundation, the WHO, the Kenya Medical Research Institute, the NTD Support Center at the Task Force for Global Health, and Merck's Mectizan Donation Program. About 3.9 million Kenyans, mainly along the Indian Ocean coast, are at risk, and over 2.5 million dual-therapy treatments were given in 2017. Deworm the World has supported Kenya's lymphatic filariasis program, housed in the country's neglected tropical disease unit, since 2017, with restricted funding from the END Fund.
2019 (January 31)	Program launch	Pakistan holds its first-ever school-based deworming day in Islamabad, launching the government's "Deworm Islamabad Initiative" to reach 570,000 children at risk of worm infections. Deworm the World provides technical assistance alongside the Pakistani organization Interactive Research & Development and the Indus Health Network, for a program led by the Ministry of Planning, Development & Reform. The partners' October 2018 call for independent monitors cites a 2016 national survey finding over 16 million school-age children in Pakistan at risk, and plans for teachers to give each child, enrolled in school or not, one 500 mg mebendazole tablet, followed by a mop-up day and an independent coverage survey, aiming to treat over 75% of school-age children. The first round had been scheduled for December 3, 2018. About a week after the launch, on February 8, India holds National Deworming Day for the sixth year running, targeting about 245 million children.
2019	Organizational	Deworm the World concludes its support for Vietnam's school-based deworming program at the end of a three-year project with Thrive Networks, funded by Dubai Cares. Unusually for the initiative, Vietnam's government had already been running school deworming at scale, so the support focused on improving it. Provincial campaigns are shortened to one or two days and synchronized across four provinces; a 2015 survey finds more than 1,300 remote satellite schools (about 40% of schools but 10% of the population) left out, and all are targeted by 2018; health workers, who deliver treatment in Vietnam, and teachers receive training; and independent monitoring finds coverage above 95% in every round. Prevalence among school-age children in Thanh Hoa province falls from 17.8% to 6.6%. In 2018 the government adopts WHO-aligned national deworming guidelines, which it uses to scale back treatment where prevalence is low. The initiative supports delivery of nearly 3 million tablets; results of a randomized trial adding a hygiene-education cartoon to deworming are still pending when Evidence Action reviews the partnership in April 2020.
2019	Impact assessment	The journal Parasites & Vectors publishes results from a five-year impact evaluation of Kenya's national school-based deworming program, run with technical assistance from Deworm the World, showing soil-transmitted worm infections falling from 32.3% in 2012 to 13.5% in 2017. The evaluation follows a monitoring design whose 2012 baseline the same journal had published in 2013. Evidence Action highlights the results in its March 2019 newsletter, along with the listing of its Kenya work in Future Crunch's "99 Good News Stories You Probably Didn't Hear About in 2018". A later survey would put the decline in prevalence since 2012 at 82%.
2019	Organizational	Deworm the World ends its formal technical assistance role in Ethiopia's national school-based deworming program, which it had advised since late 2014, though it says it continued serving "Ethiopia's TAG into 2020". With its Vietnam support also ending in early 2019, GiveWell's November 2021 review describes Deworm the World's unrestricted funding as fully supporting its program in Nigeria and covering part of program costs in India, Kenya, and Pakistan. GiveWell keeps Deworm the World as a top charity in that review, estimating a cost of about $0.66 per child dewormed in Kenya (roughly half that in India) and $6.4 million in room for more funding for 2022 to 2024, while noting that worm burdens in the areas it serves are lower on average than in the studies behind deworming's evidence base.
2019	Funding	Good Ventures, in partnership with the Open Philanthropy Project, makes a $10.4 million grant to Deworm the World, following GiveWell's 2018 recommendation of it as a top charity; the grant is about seven times the $1.5 million Good Ventures gave the initiative in 2013. Evidence Action's Dispensers for Safe Water program, a GiveWell "standout charity", receives $100,000 at the same time.
2019 (September 11)	Debate	Cochrane publishes an update of its review, now titled "Public health deworming programmes for soil-transmitted helminths in children living in endemic areas", by David Taylor-Robinson, Nicola Maayan, Sarah Donegan, Marty Chaplin, and Paul Garner. Adding six new trials and addressing comments and criticisms of the 2015 edition, it covers 51 trials: one mortality trial with over one million children, and 50 others with 84,336 participants. The review finds that regularly treating all children with deworming drugs does not appear to improve height, haemoglobin, cognition, school performance, or mortality. Evidence on school attendance is inconsistent and at risk of bias, and the effect on weight is uncertain: a few older studies, including two trials in one high-burden area of Kenya carried out over 30 years earlier, show large gains, while studies since 2000 show little or no average gain. The authors caution against "selecting only the evidence from these older studies as a rationale for contemporary mass treatment programmes", and state that the 2015 conclusions have not changed. They declare that none of them is paid for promoting or delivering deworming programmes.
2019	Expansion	With support from Evidence Action and partner Interactive Research & Development, Pakistan's Federal Ministry of Planning, Development and Special Initiatives incorporates the deworming program into the government's five-year plan. In 2021, the government would launch its first national deworming awareness campaign for the Pakistan Deworming Initiative.
2019	Background	Kremer, Duflo, and Abhijit Banerjee are awarded the Nobel Memorial Prize in Economic Sciences. In a congratulatory post, Evidence Action CEO Kanika Bahl credits Kremer's early research in Kenya, which found that free school deworming could cut absenteeism by up to 25 percent, as the origin of Deworm the World, and notes that Kremer's research also led to Evidence Action's other flagship program, Dispensers for Safe Water.
2020 (March 11)	Implementation	Kenya's National School-Based Deworming program, which with technical assistance from Deworm the World since 2012 treats over six million children a year across 27 counties, usually in two waves with teachers giving the tablets, holds its first 2020 wave in 14 counties. Four days later, on March 15, as COVID-19 cases rise, the government closes schools and imposes social distancing, which leads to the cancellation of the second wave planned for later in the year. While schools stay closed through 2020, Deworm the World's Kenya team updates all the program's training and communication materials to follow the health and education ministries' COVID-19 guidelines (social distancing, a universal mask mandate, and hand sanitizer or handwashing facilities), so that deworming can restart once schools reopen. Many at-risk children would go more than a year without being dewormed.
2020 (May 1)	Funding	Weeks after the World Health Organization declares COVID-19 a pandemic, Evidence Action, Deworm the World's parent organization, takes out a two-year, $500,000 loan at a 1% fixed rate under the United States Paycheck Protection Program, created by the CARES Act. Its 2019 audited financial statements, issued in August 2020, state that "any potential financial or operational impacts from COVID-19 are unknown at this time". The Small Business Administration would forgive the loan in 2021, and Evidence Action would record it as contribution income. Deworm the World's program spending falls from $12.4 million in 2019 to $8.3 million in 2020, before recovering to $9.6 million in 2021.
2020 (September–October)	Implementation	With schools closed by COVID-19, India holds its National Deworming Day round through door-to-door, community-based treatment for the first time, a model Deworm the World helps design. The last round before the pandemic, starting on 10 February 2020, had targeted about 300 million children and adolescents aged 1 to 19 across 34 states and union territories. The government had declared deworming an essential health service; in August 2019 the school-based round had treated more than 255 million children. Community health workers known as Accredited Social Health Activists, who normally only mobilize out-of-school children, now give the tablets to each child at home, trained in masks, distancing, and hand hygiene, and treatment is barred in COVID-19 containment zones. States may spread the round over 7 to 15 days through October 2020. Deworm the World writes implementation guidelines and awareness campaigns, moves most training online, adapts reporting, and directly supports 11 states. Its hardest task is drug supply: over 60% of India's albendazole is made with Chinese raw ingredients, and disrupted imports leave gaps that it helps fill with WHO-donated drugs. With schools still closed, the first 2021 round, from February to April, again uses door-to-door delivery.
2021 (March 3–4)	Implementation	Kenya resumes school-based deworming with a wave targeting 2.8 million children in 7 of its 27 counties, prepared in under three weeks instead of the usual two months or more. Schools had reopened on January 4, 2021, but with a compressed academic calendar and limits on extracurricular activities that rule out the usual teacher training. After Deworm the World and its government partners press for a modified program in January and February meetings, the Permanent Secretaries of the health and education ministries agree to a wave before the Easter break. The hardest task is the drugs: the program has recently moved from albendazole donated through the WHO to a model in which the government buys it locally, which usually takes months. Deworm the World helps the Ministry of Health's Division of Adolescent and School Health secure 2.8 million tablets locally, and the training cascade, which runs from county "master trainers" down to teachers, is fast-tracked with extra trainers from the Ministry of Health. A second wave targeting about 4 million children in 20 counties is planned for June 2021.
2021 (March 31)	Research	Joan Hamory, Miguel, Michael Walker, Kremer, and Baird publish "Twenty-year economic impacts of deworming" in PNAS, after circulating it as a working paper in July 2020. Tracking 84% of PSDP participants up to 20 years later, when most are 29 to 35 years old, they find that two to three extra years of childhood deworming raise consumption expenditure by 14% and hourly earnings by 13%, with effects concentrated among men and older individuals, and estimate a conservative annualized social internal rate of return of 37%. Evidence Action presents the results as validating GiveWell's recommendation of Deworm the World, and Kenya's Director of Primary Education credits the original research with informing the national program.
2021 (August 30)	Implementation	Evidence Action reports how Deworm the World's programs are adapting as COVID-19 continues. In India, ten supported states plan to keep the community-based delivery introduced in 2020, and one to mix community and school delivery, for a National Deworming Day round between August and October targeting about 206 million children aged 1 to 19, even as frontline health workers also take on COVID-19 vaccination and testing. In Nigeria, it helps Lagos State run its first large-scale deworming campaign in May, targeting 1.3 million school-age children in the country's COVID-19 epicenter; Ogun State deworms for the fifth year running and Oyo State follows in July, but supply problems delay Rivers State's planned round for about a million children. In Pakistan, where schools have been mostly closed for a year and a half, rounds are planned from August to October for about 10 million children in Islamabad, Punjab, Khyber Pakhtunkhwa, and Sindh, using community health workers to reach children in madrassas, unregistered private schools, and out of school, and the government launches its first national deworming awareness campaign. In Kenya, a second 2021 wave for about 4 million children is planned for September.
2022	Debate	The Happier Lives Institute, while replicating GiveWell's cost-effectiveness analysis of deworming, argues that GiveWell's model assumes deworming's economic benefits last 40 years without decline, whereas the Kenya Life Panel Survey data it relies on suggest the effects decay over time. By HLI's estimate, incorporating a decay of about 12% would push many of GiveWell's recommended deworming charities below GiveWell's bar of being 10 times as cost-effective as cash transfers from GiveDirectly.
2022	Funding	Evidence Action's revenue jumps from $21.3 million in 2021 to $127.5 million, and its net assets more than double to $178.5 million. Its audited statements attribute about 70% of the year's revenue to awards from a single, unnamed donor, and its Form 990 lists one contributor at $105.7 million. Most of the new money is donor-restricted for future years: spending in 2022 is only $32.5 million. From this year, Evidence Action no longer reports Deworm the World as a separate program; it reports it within a "Nutrition" program that also covers iron and folic acid supplementation. In its 2022 Form 990, Evidence Action says Deworm the World has helped deliver over 1.4 billion treatments to children since 2014; the 2024 statements would raise this to over two billion.
2022	Impact assessment	A survey of soil-transmitted worm infections in Kenya, carried out in September 2021 and May–June 2022 by Evidence Action and the Kenya Medical Research Institute after nine rounds of national school-based deworming, finds that prevalence has fallen by 82% since 2012. Published in Heliyon in October 2023, the survey of 13,416 children in 200 schools, designed with model-based geostatistics, estimates prevalence at 5.8%, against 32.3% at baseline. It recommends that 10 of the 27 counties, now below 2%, consider suspending treatment, that 10 more treat every two years, and that 7 keep annual treatment. Moderate-to-heavy infections fall to 1.3% overall, below the WHO threshold for eliminating worms as a public health problem, but 8 counties, led by Bungoma at 8.1%, remain above it. Results like these would lead GiveWell to conclude in 2024 that its cost-effectiveness model is unsuited to places such as Kenya, where worm prevalence has dropped sharply from baseline, and would shape Evidence Action's plans to hand the program over to the Kenyan government.
2022 (August)	Evaluation	GiveWell updates its criteria for top charities, and the Deworm the World Initiative, a top charity since 2013, is no longer on the list, though it remains eligible for grants from GiveWell's All Grants Fund. GiveWell states that the change does not reflect an update in its view of the program; Evidence Action explains that GiveWell's top-charity fund is meant for individual donors who may prefer programs with higher certainty. Evidence Action notes that GiveWell's funding for Deworm the World over nine years has totaled more than $42 million. Some effective-giving platforms keep recommending it: Germany's Effektiv Spenden continues to present Deworm the World as one of its top charities, saying GiveWell's high rating of the organization "remains undiminished".
2023 (January)	Funding	GiveWell makes a $5.2 million grant to Deworm the World, extending support through 2025 for five Nigerian states (Ogun, Oyo, Rivers, Lagos, and Cross River; $3.4 million), Pakistan's Khyber Pakhtunkhwa province ($1.0 million), and Kenya ($0.9 million), alongside a separate $2.5 million grant for India. With GiveWell's funding bar now at ten times the cost-effectiveness of cash transfers, it estimates the grant at about 16 times overall, ranging from 35 times in Kenya to 7 times in Khyber Pakhtunkhwa, and declines to renew support for the rest of Pakistan, estimated at only 1 to 5 times, leaving Deworm the World to raise funds there elsewhere. GiveWell adds an adjustment for the possible decay of deworming benefits over time, which lowers its estimates by about 10%, and notes that the UK government ended its support for Nigeria's programs in 2021. It flags risks that its funding crowds out other funders in Kenya, and that WHO's 2022 schistosomiasis guideline may push countries toward more targeted treatment.
2023 (February 16)	Research	The Journal of Laboratory Physicians publishes a systematic review and meta-analysis by Chopra, Shekhar, and Dagar of soil-transmitted worm prevalence among children in India, drawing on more than 1,400 English-language articles published up to 2021; it finds especially high prevalence in hill states, which an accompanying editorial attributes to scarce safe water and poor hygiene. In that editorial, titled "Deworm the World Initiative: How much Progress India has Made?", Sarman Singh of AIIMS recalls the initiative's early Indian surveys and argues that eliminating worm infections is a national priority that needs several ministries working together, not health alone. He credits the Swachh Bharat Mission with significant strides against open defecation (the government declared India open-defecation-free in October 2019), while warning that the facts on the ground may differ. He also notes that the review does not compare prevalence before and after mass deworming began, and that the effect of COVID-19, when schooling moved online and poor families could not afford it, "is yet to be seen and reported".
2023 (April 5)	Evaluation	Founders Pledge, an impact-focused charity evaluator, updates its recommendation of Deworm the World, on a page whose sources were retrieved in early 2021. Its case rests largely on GiveWell, which it calls its research partner in global health and describes as recommending the initiative as one of the world's most cost-effective development organizations, even though GiveWell had removed it from its top charities in 2022. Founders Pledge cites strong evidence that deworming drugs reduce worm loads and "some evidence" that this improves life outcomes, and estimates that as of March 2023 the initiative could usefully spend an additional $1.4 million in its most cost-effective regions over 2023–2026: $0.8 million in Nigeria, $0.4 million in India, and $0.2 million in Kenya. On the strength of Founders Pledge's recommendation, Giving What We Can adds Deworm the World to its recommended charities; it would later limit its list to organizations backed by evaluators it has investigated and decided to rely on, dropping the initiative while still accepting donations to it. Founders Pledge would go on to fund Deworm the World's program in Tanzania, announced in January 2026.
2023 (August)	Strategy	Pakistan's Ministry of Planning, Development and Special Initiatives issues the National Strategic Framework and Operational Guidelines 2022–27 for the Pakistan Deworming Initiative, drafted with technical assistance from Interactive Research & Development, Evidence Action, and the WHO. It recounts that the initiative, launched in 2018 after the 2016 national survey found over 16 million school-age children at risk in 45 districts, began treatment in Islamabad in 2019, but that COVID-19 school closures for most of 2020 and 2021 delayed the planned national scale-up. Reported treatments fall from 2.9 million (37% coverage) in 2019 to about 435,000 in 2020, then recover to 8.3 million in 2021 and 12.3 million (72%) in 2022, when first rounds in Balochistan, Gilgit-Baltistan, and Azad Kashmir bring the program to every at-risk district. The framework aims to eliminate soil-transmitted worms as a public health problem, offering deworming to over 16 million school-age children a year at an estimated cost of US$21.6 million over five years, under 50 cents per child, and urges provincial governments to allocate their own resources to sustain the program.
2023 (November 23)	Research	Economists Edward Miguel, Eric Ochieng, and Michael Walker summarize on VoxDev the first experimental evidence that the Kenyan school deworming program studied by Miguel and Kremer benefited the next generation. Their NBER working paper with Kremer, Sarah Baird, Joan Hamory Hicks, and other co-authors, "Intergenerational Child Mortality Impacts of Deworming", draws on the Kenya Life Panel Survey, which has followed about 7,500 of the program's pupils since 2003, reaching 86.5% of them. Children born to people who received about 2.4 additional years of deworming in 1998–2001 have an under-five mortality rate lower by 17 deaths per 1,000 births, a 22% reduction from the control group's 76; a 15% reduction in infant mortality is not statistically significant. The study cannot isolate a single mechanism, but parental health, education, living standards, later first births, and access to health care all move in directions associated with lower child mortality. The authors argue the results widen the case for subsidizing child health investments such as deworming. A companion study of 3,500 of the participants' children aged 3 to 8 finds better parent-reported health and socioemotional development, and higher math and language scores among older children, except those most affected by COVID-19 school closures.
2024 (March)	Funding	GiveWell recommends a $4.4 million grant to renew support for Deworm the World's programs in selected locations in Nigeria, Pakistan, Kenya, and India through 2026. GiveWell acknowledges a flaw in its cost-effectiveness model that makes it unsuited to places like Kenya and India, where impact assessments show sharp declines in worm prevalence from baseline, and says it has renewed support for Indian states on a largely qualitative basis. It gives a 50% probability that it will not renew support for Kenya in its next grant cycle, while Deworm the World plans a follow-up impact assessment to inform a possible exit from Kenya around 2028.
2024 (June 10)	Debate	The WHO highlights a new meta-analysis, published in PNAS, that it says reaffirms significant health benefits of mass drug administration against soil-transmitted worms and shows it to be cost-effective. Noting that recent Cochrane meta-analyses endorse treating infected individuals but recommend against mass treatment, the study's random-effects meta-analysis of multiple-dose mass deworming finds significant effects on child weight (0.15 kg), mid-upper arm circumference (0.20 cm), and height (0.09 cm) where prevalence exceeds 20%, but no significant effect on haemoglobin. The authors conclude that mass treatment is cost-effective, particularly in the settings where the WHO recommends it. The weight estimate closely matches the 0.148 kg effect that Croke, Hicks, Hsu, Kremer, and Miguel reported in 2017 from their working-paper meta-analysis for areas above 20% prevalence.
2024	Expansion	Evidence Action launches Deworm the World in Malawi together with its Equal Vitamin Access program, pairing school deworming with iron and folic acid supplementation and sharing planning, teacher and health worker training, and community mobilization between the two. Working with Malawi's Ministry of Health across all 28 districts, it aims to reach more than 3.5 million children over three years in a country where over half of children suffer from worms and anemia. The launch is funded by the IMC Pacific Foundation, the Ray and Tye Noorda Foundation, and the Weiss Asset Management Foundation. Evidence Action says the integrated design cuts costs by 12% and will reach children for under $1.35 per child per year by the third year; it would secure funding through 2027 and seek partners to fund the program through 2030.
2025 (May)	Funding	GiveWell makes a grant funding Deworm the World's work through 2027: continued funding in Nigeria and exit funding for Kenya and Pakistan. GiveWell extends the timeline so that any post-exit treatment and surveillance strategy developed with the Kenyan government can rest on the latest worm-burden evidence. Deworm the World reports no changes to its 2025 deworming plans as a result of that year's foreign aid cuts.
2025 (October)	Impact assessment	Evidence Action launches the National Impact Survey for Pakistan's deworming program, which it has supported since 2019 and which now reaches about 14 million children a year. Using microscopic analysis of stool samples to measure the prevalence and intensity of worm infections, the survey is meant to measure the impact of past deworming rounds and guide the program's strategy, following the pattern of earlier impact assessments in Kenya and India that led to scaled-down treatment there. In its January 2026 appeal, Evidence Action would estimate that three to five more treatment rounds could let Pakistan reduce prevalence enough to scale down the program and hand it over to the government.
2025	Organizational	In a year when development funding contracts globally, Deworm the World supports deworming campaigns reaching about 183 million children across five countries, according to Evidence Action's review of the year. In India, after a decade of treatment supported by Evidence Action, several states have eliminated parasitic worms as a public health problem: impact assessments show prevalence below 1% in Himachal Pradesh and Rajasthan, and a fall from 75% to 14% in Chhattisgarh. Evidence Action scales back or concludes its support in these states as they show they can maintain the programs on their own. In Kenya, where worm infections have fallen by over 80% since its support began in 2012, it prepares for a complete handover to the government, with Kenya positioned to eliminate worms as a public health problem by 2027. In Nigeria, seven years of technical assistance in Cross River State help cut soil-transmitted worm prevalence by 49% and schistosomiasis by 75%, reshaping the state's deworming strategy. In Malawi, iron and folic acid supplementation layered onto the deworming program reaches more than 1.3 million adolescent girls in 15 districts. The August 2025 National Deworming Day in India treats 146.8 million children.
2026 (January 7)	Expansion	Evidence Action announces the launch of Deworm the World in Tanzania, with support from Founders Pledge, where more than 10 million children are at risk of or infected with soil-transmitted worms or schistosomiasis. Rather than backing a full mass treatment campaign, the program provides technical assistance (mass drug administration planning, follow-up surveys, and the country's first nationwide prevalence survey in over 20 years) to help Tanzania eliminate worms as a public health problem by 2030, the WHO target. Tanzania has traditionally treated in all 184 district councils, but recent surveys find low soil-transmitted worm prevalence (3.4%) and uneven schistosomiasis (9.3% overall, 63% in high-risk communities); Evidence Action expects the new survey to let Tanzania halve the number of districts needing mass treatment. The launch follows the suspension of external funding for Tanzania's program in 2025, after which every district council budgets for its own deworming; the government targets 60% domestic financing of neglected tropical disease programs by 2026. Tanzania had been one of the nine countries Kremer and Zwane named in 2014 as needing to scale up deworming. Evidence Action's review of 2025 counts the partnership as launched that year.
2026 (January)	Evaluation	GiveWell publishes a lookback on roughly $10 million in grants since 2013 supporting Deworm the World's technical assistance for National Deworming Day in Indian states (procurement monitoring, training, logistics, and coverage surveys). Government data show coverage rising from about 55% before assistance to about 80% three years later, but GiveWell finds large discrepancies, with no consistent direction, between Evidence Action's independent coverage surveys and government data, and between prevalence surveys by Evidence Action-supported research institutes and by India's National Centre for Disease Control. Its best-guess retrospective estimate is about 8 times its cost-effectiveness benchmark (range 2 to 16 times), near its 10x bar. GiveWell says it would make the grants again, and commits to funding baseline data and meeting government officials without grantee staff present in future.
2026 (January 30)	Funding	On World Neglected Tropical Diseases Day, Evidence Action launches a fundraising appeal, "Don't gamble away NTD gains", warning that funding for neglected tropical diseases has collapsed. Official development assistance for them fell 41% between 2018 and 2023, before cuts to USAID made things worse, and the WHO's 2025 Global NTD Report warns that programs are being "severely disrupted". With more than 627 million school-age children still at risk of worm infections, Evidence Action argues that infections could return to baseline levels without sustained funding. It reports that Deworm the World has supported over 2.2 billion treatments since 2014, and claims about $169 in economic returns for every dollar invested. In Pakistan, where it supports deworming for over 14 million children a year, it warns the program may wind down prematurely, although three to five more rounds could allow a handover to the government; it notes that Pakistan gets a third of the development assistance Nigeria does despite similar population and health indicators. In Nigeria, surveyed states show falls of more than 49% in soil-transmitted worm prevalence and over 75% in schistosomiasis.
2026 (May 21)	Impact assessment	Evidence Action reports that an impact assessment carried out with Nigeria's Federal Ministry of Health in Cross River State finds soil-transmitted worm prevalence down 48.5% and schistosomiasis down 76% after nearly a decade of school-based deworming it has supported. Its Nigeria program has grown from fewer than 500,000 children treated in its first year to more than 6.5 million in 2025, and since 2016 it has trained more than 32,000 health workers and teachers and supported more than 44 million treatments across several states. The 2026 campaign aims to treat about five million children, slightly fewer than in previous years, because states such as Cross River now need less frequent treatment under WHO guidelines. Governor Bassey Edet Otu invites Evidence Action to discuss an elimination strategy for neglected tropical diseases and approves a budget allocation for the 2026 round on the spot (reported in local press as ₦64 million), which Evidence Action presents as a step toward the state sustaining the program and eliminating these diseases by 2030.

Numerical and visual data

Evidence Action finances

Deworm the World has no separate accounts, so the table below shows figures for Evidence Action, its parent organization since 2013. Figures for 2018 onward come from the audited consolidated financial statements, which include the Kenya branch and the foreign affiliates (Uganda, Malawi, Nigeria, and India, among others). Figures for 2013 to 2017 come from Evidence Action's Form 990 filings, which cover only the U.S. entity and therefore differ slightly from consolidated figures for the same year. Up to 2021, the audited statements report Deworm the World as its own program; from 2022, it is reported within a "Nutrition" program that also includes iron and folic acid supplementation. All amounts are in US dollars.

Year	Total revenue and support	Total expenses	Deworm the World program expenses	Net assets (end of year)	Notes
2013	2,859,389	196,810		2,662,579	Form 990. Evidence Action receives tax exemption in October 2013.
2014	15,783,136	4,743,616		13,702,099	Form 990.
2015	7,979,473	13,599,449		8,082,123	Form 990.
2016	25,018,508	15,724,235		17,337,232	Form 990.
2017	64,317,406	19,154,356		62,676,897	Form 990.
2018	35,866,216	22,581,010	10,483,359	76,035,433	Audited. Net assets restated in the 2019 statements.
2019	34,571,014	24,395,411	12,395,444	85,623,901	Audited. About 44% of revenue comes from grants by three donors.
2020	24,639,117	23,474,895	8,299,093	86,412,029	Audited. About 30% of revenue comes from three donors.
2021	21,329,586	22,696,192	9,620,444	83,547,224	Audited. About 28% of revenue comes from three donors. The 2022 statements restate 2021 program spending on the new basis, with Nutrition at 10,858,189.
2022	127,488,594	32,543,612	12,352,696 (Nutrition)	178,453,962	Audited. About 70% of revenue comes from awards from one donor.
2023	57,879,617	37,600,175	10,592,847 (Nutrition)	198,552,346	Audited. About 36% of revenue comes from two donors.
2024	37,649,889	43,928,025	14,018,265 (Nutrition)	192,258,021	Audited. About 50% of revenue comes from four donors. Includes 8,950,217 of net investment return.

Meta information on the timeline

How the timeline was built

The initial version of the timeline was written by FIXME.

Check Detail construction for full timeline in timelines, Inclusion criteria for full timeline in timelines, and Representativeness of events in timelines.

Funding information for this timeline is available.

Feedback and comments

Feedback for the timeline can be provided at the following places:

• FIXME

Timeline update strategy

Check GiveWell's grants pages and lookbacks for Deworm the World, Evidence Action's annual reviews and newsroom, and the results of each National Deworming Day round in India (February and August).

See also

• Timeline of GiveWell
• Timeline of Against Malaria Foundation

External links

• Evidence Action (official website)
• Deworm the World on the Evidence Action website
• GiveWell's review of Evidence Action's Deworm the World Initiative
• Deworm the World Initiative on Wikipedia