Children with deworming medication.

School children in Chhattisgarh, India are ready to take their deworming medication on National Deworming Day. © Evidence Action

Ahuja, Amrita, Sarah Baird, Joan Hamory Hicks, Michael Kremer, and Edward Miguel. 2017. “Economics of Mass Deworming Programs.” Disease Control Priorities: Child and Adolescent Health and Development 8: 413-422.
Ahuja, Amrita, Sarah Baird, Joan Hamory Hicks, Michael Kremer, Edward Miguel, and Shawn Powers. 2015. “When Should Governments Subsidize Health? The Case of Mass Deworming.” The World Bank Economic Review 29: S9-S24. Publisher's Version Abstract

We discuss how evidence and theory can be combined to provide insight on the appropriate subsidy level for health products, focusing on the specific case of deworming. Although intestinal worm infections can be treated using safe, low-cost drugs, some have challenged the view that mass school-based deworming should be a policy priority. We review well-identified research which both uses experimental or quasi-experimental methods to demonstrate causal relationships and adequately accounts for epidemiological externalities from deworming treatment, including studies of deworming campaigns in the Southern United States, Kenya, and Uganda. The existing evidence shows consistent positive impacts on school participation in the short run and on academic test scores, employment, and income in the long run, while suggesting that most parents will not pay for deworming treatment that is not fully subsidized. There is also evidence for a fiscal externality through higher future tax revenue, which may exceed the cost of the program. Our analysis suggests that the economic benefits of school-based deworming programs are likely to exceed their costs in places where worm infestations are endemic. This would likely be the case even if the benefits were only a fraction of estimates in the existing literature.

Kremer, Michael, and Edward Miguel. 2004. “Worms: Identifying Impacts on Education and Health in the Presence of Treatment Externalities.” Econometrica 72 (1): 159-217. Publisher's Version Abstract

Intestinal helminths—including hookworm, roundworm, whipworm, and schistosomiasis—infect more than one‐quarter of the world's population. Studies in which medical treatment is randomized at the individual level potentially doubly underestimate the benefits of treatment, missing externality benefits to the comparison group from reduced disease transmission, and therefore also underestimating benefits for the treatment group. We evaluate a Kenyan project in which school‐based mass treatment with deworming drugs was randomly phased into schools, rather than to individuals, allowing estimation of overall program effects. The program reduced school absenteeism in treatment schools by one‐quarter, and was far cheaper than alternative ways of boosting school participation. Deworming substantially improved health and school participation among untreated children in both treatment schools and neighboring schools, and these externalities are large enough to justify fully subsidizing treatment. Yet we do not find evidence that deworming improved academic test scores.

Mass Deworming

"Worms: Identifying Impacts on Education and Health in the Presence of Treatment Externalities," with Edward Miguel, Econometrica 72:1 (January 2004):159-217. (NBER Working Paper 8481, 2001)

"The Illusion of Sustainability," with Edward Miguel. Quarterly Journal of Economics 122(3) (August 2007): 1007-1065. Reprinted in Reinventing Foreign Aid, ed., William Easterly. Cambridge (Mass.): The MIT Press, 2008 (NBER Working Paper 10324, 2004.) 


Articles and Blogs on the Research on Worms

Comment on Macartan Humphreys' and Other Recent Discussions of the Miguel and Kremer (2004) Study - Edward Miguel, Michael Kremer, and Joan Hamory Hicks, December 22, 2015

Worming our way to the truth - Tim Hartford July 31, 2015, in the Financial Times

Mapping the Worm Wars: What the Public Should Take Away from the Scientific Debate about Mass Deworming - Michael Clemens and Justin Sandefur, July 30, 2015, Center for Global Development

Worm Wars: A Review of the Reanalysis of Miguel and Kremer's Deworming Study - Berk Ozler July 24, 2015 World Bank blog on impact evaluations

New deworming reanalyses and Cochrane review - Alexander July 24, 2015, The GiveWell Blog

Information on Scaling Up Deworming

Summary on Scaling Deworming