Evidence Action engages in a rigorous and systematic approach to identify development interventions that we can turn into programs that benefit millions of people with real and proven results. That is what sets us apart from most global development organizations. All programs that we undertake have a strong evidence base generated from peer-reviewed, rigorous evaluations that demonstrate a clear causal chain, most often in the form of randomized control trials (RCTs). But when we consider scaling a program, we do not rely solely on RCTs. We take into consideration other factors that help us understand whether a program effect is resilient across different contexts, and holds true over time through examining the mechanisms at play that generate a given effect.

Replications and additional substantiations of original research that add weight and context when determining whether an intervention has the desired effect, are an important piece in our methodology. Expanding original research to new situations in order to determine whether the intervention’s impact is generalizable across different contexts, including location, culture, or other variables, is critical for us. As the evidence base grows we gain a solid understanding of the fundamentals at work and have confidence that the desired results hold when implemented in very different environments.

Evidence Action’s Deworm the World Initiative is a good example of a program that is bolstered by a well-rounded and very strong evidence base that highlights the positive impacts of mass deworming on children’s cognition and education across diverse settings.

And now there is new evidence that further supports that mass deworming works and even has long-term effects.

Evidence on the cognitive and educational benefits of deworming children has been substantiated in a variety of studies across locations in Kenya, Uganda, and India. We have previously documented this research. Each previous study focused on deworming school-aged children and resulted in repeated positive impacts such as increased days of school attendance, weight gain, improved cognitive development, and higher future earnings. A rigorous randomized evaluation in Western Kenya found a 25 percent reduction in student absenteeism at schools treated with deworming (Miguel and Kremer 2004).  Baird and colleagues (2012) tracked educational outcomes of participants in the original Kenya study and found students who were dewormed had a higher passing rate of the Kenya Certificate of Primary Education exam by 6.1 percentage points, on a base of 41.3 percent. Similarly, in Eastern Uganda, Alderman and colleagues (2007) conducted a cluster randomized controlled trial where deworming school aged children results in a 10 percent gain in weight for treated children.

Now there are two new and very clever follow-up studies that further emphasize the long-term positive impacts of deworming children. Independent researchers revisited the original studies conducted in Kenya and Uganda and tracked previous program participants beyond the experimental timeline. They found improved learning outcomes and cognitive development among children treated for worms and even siblings not treated — years after treatment.

In Uganda, Kevin Croke followed up on Alderman and colleagues’ 2007 study by tracking children 7 to 8 years after the original deworming period. Croke finds that dewormed children have higher test scores in literacy and numeracy than the non-treated children in the initial program. Croke then conducted a number of robustness checks to ensure that there were not other variables influencing these results.  For instance, he checked whether access to water, the mother’s education, and district fixed effects had an impact on the higher test results of the children studied. He concluded that the improvements to learning outcomes indeed are linked to deworming, as opposed to other unobservable factors.

Similarly, researcher Owen Ozier built upon Miguel and Kremer’s initial 2004 research in Kenya by assessing the impact of deworming on preschool-age children whose older siblings were dewormed as part of the original study. Ozier found that there is strong evidence of large cognitive improvements among children whose siblings were dewormed. These were not even children who were treated themselves – they were the untreated younger siblings. The healthier older children reduced infection rate among their preschool-aged siblings which improved cognitive development for the preschool-aged children across a variety of cognitive tests.

These follow-up studies further strengthen Deworm the World’s theory of change that mass deworming children has long-term impacts on cognitive development and improved learning outcomes and a cost-effective and highly scalable development intervention. Given that Deworm the World treated more than 45 million children just this last school year, we are thrilled to see that the relevancy and proven impact of our work continues to grow.

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