The findings of the 2004 study were startling: A campaign to treat thousands of children in western Kenya for parasitic worms yielded significant, long-term health and educational benefits. Across the 75 primary schools involved, rates of intestinal worms and student absenteeism decreased—the latter by around 25 percent compared to the control—suggesting, essentially, that healthier kids stayed in school. Now, two decades since the first deworming treatment, lead researchers Edward Miguel, a professor of environmental and resource economics at UC Berkeley, and Nobel Prize-winning economist Michael Kremer, are back with more data and even bigger conclusions.
Calculating the overall costs and benefits to society, this small investment—less than a dollar per kid per year—yielded a 37 percent rate of return annually. “People’s lives really changed,” says Miguel, explaining that those same kids who stayed in school became adults who sought higher-paying jobs, enjoyed greater disposable income, and ultimately contributed more to their local economy. “All of this because of a health treatment that was really, very cheap.”
Does it all come down to education? Miguel says it’s complicated. “Say I’m a student in the treatment school, not only did I get treated, but all the other kids in a treatment school also got treated. So not only was my health better, but the health and education of my peer network was better, too.” The researchers found that former school friends often helped each other land higher-paying jobs. In this way, the benefits of the program multiplied over time, and even spilled over into untreated communities.
However, not everyone agrees. During the so-called “Worm Wars” of 2015, researchers from the London School of Hygiene & Tropical Medicine claimed to have debunked the original study. While Miguel and Kremer were able to correct some coding and statistical errors, critics remain skeptical. Also, what accounts for continued economic disparities between men and women? Can the benefits of deworming carry over to future generations? And will the findings apply outside of East Africa, in places where worm loads are typically much lower?
These are questions the team is actively trying to answer. But, in the end, Miguel insists, one thing is clear. “Deworming is just a very cost-effective way to boost living standards. It’s not going to double income. But if something very cheap can even improve living standards by a few percent, for the world’s poorest people, that’s really valuable.”