A new landmark study by a team of economists, led by Edward Miguel and Nobel laureate Michael Kremer, offers new evidence of the long-term benefits of school-based deworming. According to the study, which followed a group of Kenyan students every 5 years over a 20 year period, receiving two to three additional years of deworming increased their income by 13% and consumption by 14% decades after treatment.

As an organization that supports deworming for hundreds of millions of children each year in Kenya, Nigeria, India, and Pakistan, this study further proves the impact of our work years after the children leave school. 

A study 20 years in the making

When Miguel and Kremer first began studying the impact of school-based deworming treatments in the early 2000s, parasitic worm infections were shockingly prevalent. According to estimates from the World Health Organization at the time, these infections afflicted 1 in 4 people globally. While treatment was available, access was limited in many countries and distributed sporadically by charities at small scale. 

In 2004, Michael Kremer and Edward Miguel published the results of a study that changed this picture substantially. Through a randomized controlled trial in Western Kenya, they found that children who received deworming had better health and education outcomes – including a 25% decrease in school absenteeism – when compared to those who did not. Spillover effects were also observed: when a whole school was treated for worms, the parasites became less prevalent, leading to fewer infections in the community.

These results inspired international organizations, private donors, and governments to fund, initiate, and support the scaling up of school-based deworming programs, which have grown dramatically in the last decades. This new interest led to the creation of our Deworm the World Initiative, which has operated since 2009. Today, we assist governments in Africa and Asia to provide deworming treatment to over 280 million children annually, and in total have supported provision of over a billion deworming treatments since 2014. 

Based on the positive impact of their research, the two economists could have stopped there. However, Miguel and Kremer knew there might be more to the story. They hypothesized that since deworming had improved children’s health and education outcomes in the short term, it might also affect their long-term quality of life. So, they followed the children from the initial trial every 5 years over a span of 20 years, in one of the first longitudinal studies of its kind.

On Monday, they published the results of their 20 year follow up in a new working paper. It was a collaborative effort between researchers from the University of Oklahoma, the Center for Effective Global Action (CEGA) at the University of California Berkeley, the University of Washington, Harvard University, and Innovations for Poverty Action (IPA).

The authors found that children who received deworming treatment for two or three years in a row had better quality of life decades after the fact. When compared to those who had fewer years of treatment, they reported 14% higher household consumption rates and 13% higher income. In lower income countries like Kenya, these types of increases tend to represent improvements to the individual’s and their family’s diet, access to education and health, housing, and overall living conditions. 

For a pill that typically costs less than $0.50 to deliver, these significant long-term impacts make deworming an incredibly cost-effective solution. Even in the most conservative scenario modeled, the authors found that for every dollar spent on the deworming in the trial, each person who received the treatment reaped economic benefits worth, on average, over $230. There are also important benefits to the Kenyan government – for every dollar spent on the early deworming, the researchers estimated fiscal benefits through increased tax revenue equivalent to $16.70 – meaning that deworming pays for itself many times over.

Since the groundbreaking 2004 study, a generation of Kenyan children have grown up with regular deworming – meaning they’re much less likely to have experienced infection and the negative health and educational consequences. With technical assistance from Evidence Action, the Kenyan Government began conducting national school-based deworming in 2011, covering over 75% of at-risk children at an average cost of $0.44 per child, per year. According to Kenya’s Director of Primary Education, Nerreah Olick, the new findings “highlights [the] importance of research in development programs and indicates that the government proactively uses data to inform policy direction. The research findings informed the establishment of the very successful Kenya national school based deworming program, which… has become a globally recognized, high impact model for successful cross-sectoral partnership.”

In a year when global health has taken center stage in all of our minds, one of this study’s most hopeful findings is that when we invest in cost-effective health initiatives like deworming, we can positively change the trajectories of people’s lives at an incredibly low cost. These results validate the decision of prominent charity evaluators such as Givewell to recommend our Deworm the World Initiative for eight consecutive years as one of the most cost-effective ways to do good in the world. 

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