The GiveWell Blog

Questioning the evidence on hookworm eradication in the American South


  • Four of GiveWell’s top charities support deworming—the mass distribution of medicines to children in poor countries to rid their bodies of schistosomiasis, hookworm, and parasites.
  • GiveWell’s recommendation relies primarily on research from western Kenya finding that deworming in childhood boosted income in adulthood. GiveWell has also placed weight on a study by Hoyt Bleakley of the hookworm eradication effort in the American South 100 years ago.
  • I reviewed the Bleakley study and reach a different conclusion than he did: the deworming campaign in the American South did not coincide with breaks in long-term trends that would invite eradication as the explanation.
  • GiveWell research staff took the conclusions of this post into account when updating their recommendations for the 2017 giving season. GiveWell continues to recommend deworming charities.
  • I also reviewed a separate Bleakley study of the impacts of malaria eradication in the United States, Brazil, Colombia, and Mexico. My reading there is more supporting. I’m finalizing the write-ups now and will share them soon.

Our top charities for giving season 2017

This year, we added two new top charities, Evidence Action’s No Lean Season program and Helen Keller International’s vitamin A supplementation program, and retained our seven top charities from 2016. We also added Evidence Action’s Dispensers for Safe Water program to our list of standout charities.

We recommend that donors give to GiveWell for granting to top charities at our discretion so that we can direct the funding to the top charity or charities with the most pressing funding need. For donors who prefer to give directly to our top charities, we recommend giving 70 percent of your donation to the Against Malaria Foundation (AMF) and 30 percent to the Schistosomiasis Control Initiative (SCI) to maximize your impact. We expect Good Ventures, a foundation with which we work closely, to provide significant support to each top charity; our recommendation to give to AMF and SCI is based on how much good we believe additional donations can do.

Are GiveWell’s top charities the best option for every donor?

We’re sometimes asked whether we think GiveWell’s top charities are the “best,” in some absolute sense of the word, or whether we’d ever advise that a donor give to an opportunity outside of our recommendations. This post aims to clarify how GiveWell thinks about different giving options and their suitability for different types of donors.

We believe that GiveWell’s top charities offer donors an outstanding opportunity to do a lot of good and are the best option for most donors. However, some donors—those with a very high degree of trust in a particular individual or organization to make this decision, donors with lots of time (in excess of 50 hours per year, and likely more) to consider their giving decision, or donors whose values point strongly toward a particular cause outside of the ones GiveWell covers—may find opportunities to have a greater impact per dollar than GiveWell’s top charities. Note that we think these characteristics are likely to be necessary, but not sufficient, for finding these types of opportunities; we still expect good giving to be hard, and spending, for example, 50 hours per year on research isn’t necessarily going to yield better opportunities.

In this post, we describe relevant considerations for donors in greater detail.

How thin the reed? Generalizing from “Worms at Work”

Hookworm (AJC1/flickr) My last post explains why I largely trust the most famous school-based deworming experiment, in particular the report in Worms at Work about its long-term benefits. That post also gives background on the deworming debate, so please read it first. In this post, I’ll talk about the problem of generalization. If deworming in southern Busia… Read More

Why I mostly believe in Worms

The following statements are true: “GiveWell is a nonprofit dedicated to finding outstanding giving opportunities through in-depth analysis. Thousands of hours of research have gone into finding our top-rated charities.” GiveWell recommends four deworming charities as having outstanding expected value. Why? Hundreds of millions of kids harbor parasitic worms in their guts[1]. Treatment is safe,… Read More

Our updated top charities for giving season 2016

We have refreshed our top charity rankings and recommendations. We now have seven top charities: our four top charities from last year and three new additions. We have also added two new organizations to our list of charities that we think deserve special recognition (previously called “standout” charities). Instead of ranking organizations, we rank funding… Read More