Deworm a whole classroom for a year.
School-based mass treatment: one tablet, once or twice a year, delivered by teachers who are already standing in front of the children.
Choose your ripple
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Hundreds of millions of children carry parasitic worms picked up from contaminated soil. Heavy infections cause anaemia, stunting and missed school. Most infections are light and do little harm, which is why the case rests on treating whole schools cheaply, with a single tablet, rather than trying to find the few children who are badly affected.
- Soil-transmitted helminth infectionsWorld Health OrganizationWhat the worms are, who carries them, and how mass treatment works.
- DewormingGiveWellThe contested long-run evidence, laid out by the evaluator that funds it anyway.
- Deworm the WorldEvidence ActionThe program page: countries, scale, and how school-based delivery works.
GiveWell publishes about $0.66 per child for Kenya and half that for India. We use the Kenya cost, so the figures understate elsewhere.
The figures
What Evidence Action — Deworm the World does
Deworm the World supports governments running school-based deworming programs: training teachers, supplying tablets, and monitoring whether the children actually receive them. The delivery cost is low precisely because it rides on schools that already exist.
How GiveWell gets there
GiveWell's case for deworming rests less on immediate health than on long-run economic effects: follow-up studies of dewormed children found higher earnings years later. GiveWell models that effect, then applies a large explicit discount for the chance it doesn't replicate, and still finds the intervention competitive, because the cost per child is so low.
What could be wrong
- GiveWell removed deworming from its Top Charity list in August 2022, when it raised the bar for that list. The program is still funded through GiveWell's All Grants Fund, but it no longer carries their strongest endorsement. You should weigh that before giving here rather than after.
- GiveWell's cost figures for this program were last updated in November 2020, and its review page in April 2023. We checked them against the source in September 2026 and they are still the current published numbers, but they are not recent ones, and no newer independent costing exists. Every other cause on this site rests on fresher research than this one.
- GiveWell itself no longer accepts donations earmarked for Deworm the World, which is why this cause sends you to Evidence Action instead. The form we link designates the gift to the deworming program rather than to Evidence Action's general fund.
- This is the most contested pick on the site, and we'd rather say so than bury it. The long-run income evidence rests on a small number of studies, one of which has been re-analyzed and disputed in public. GiveWell's own model applies a heavy discount for exactly this reason.
- The immediate health benefit for a typical treated child is modest. Most children treated do not have a heavy worm infection; the case rests on cheaply treating many to reach the few who do.
- If the long-run income effect turns out to be much smaller than estimated, this intervention's cost-effectiveness falls sharply, more than any other cause listed here.
- We include it because a low cost multiplied by a very uncertain benefit can still be a good bet. That's a judgment about risk, not a settled fact, and you may reasonably decline it.
Every figure is an average program cost, not a receipt. How we phrase things.