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Parasitic worms (also known as helminths) can cause a variety of health conditions and symptoms of varying severity. The most common parasitic worm infection, ascariasis, is estimated to affect 800 million to 1.1 billion people (Centers for Disease Control and Prevention 2013). Experts disagree about whether the health effects of parasitic worms are relatively minor or quite severe (Taylor-Robinson et al 2015; Croke et al 2016).

Parasitic worm infections can be treated through mass drug administration (GiveWell 2015). This method of deworming has low costs and a high level of success in reducing worm loads (though reinfection can be rapid). There is also some evidence that reducing worm loads among children results in substantial increases in future earnings (Hicks, Kremer & Miguel 2015), though some have challenged these findings (Humphreys 2015; Jullien, Sinclair & Garner 2016).

Due to the low cost and the probability that it will increase future earnings, GiveWell regards mass drug administration as a priority program (GiveWell 2016) and rates donating to deworming charities as having high expected value (Conley 2016). Two of GiveWell’s top recommended charities, Deworm the World Initiative and Schistosomiasis Control Initiative, focus on deworming through mass drug administration.

Further reading

Centers for Disease Control and Prevention. 2013. Parasites.

Conley, Sean. 2016. Deworming might have huge impact, but might have close to zero impact.

Croke, Kevin et al. 2016. Does mass deworming affect child nutrition? Meta-analysis, cost-effectiveness, and statistical power. NBER working paper no. 22382.

GiveWell. 2015. Combination deworming (mass drug administration targeting both schistosomiasis and soil-transmitted helminths).

GiveWell. 2016. Priority programs.

Hicks, Joan, Michael Kremer & Edward Miguel. 2015. The case for mass treatment of intestinal helminths in endemic areas. PLoS neglected tropical diseases 9(10): e0004214.

Humphreys, Macartan. 2015. What has been learned from the deworming replications: a nonpartisan view.

Jullien, Sophie, David Sinclair & Paul Garner, Paul. 2016. The impact of mass deworming programmes on schooling and economic development: an appraisal of long-term studies. International journal of epidemiology, in press.

Taylor-Robinson, David et al. 2015. Deworming drugs for soil-transmitted intestinal worms in children: effects on nutritional indicators, haemoglobin, and school performance. Cochrane database of systematic reviews 7: CD000371.