Intestinal worm infections are among the most widespread diseases globally today that affect more than a billion people especially in low-income countries. These parasites--roundworms, hookworms, and whipworms--affect especially school-age children, causing malnutrition, fatigue, and even organ damage and internal bleeding. Periodic and presumptive mass treatment of every child is inexpensive, considered very safe, and is recommended WHO policy in areas where worms are endemic. A number of countries have made school-based deworming part and parcel of their national health and education policies.

Yet, some have argued that the WHO recommendation of mass treatment of everyone in an affected area is not supported by enough evidence.

In a new paper, authors Amrita Ahuja, Sarah Baird, Michael Kremer et al. argue that mass deworming treatment is not only effective for children, supported by ample and growing rigorous evidence, but also smart educational and economic policy for endemic countries.

[Editor's Disclosure: Amrita Ahuja is a volunteer board member of Evidence Action.]

The authors, all development economists and public health experts who have studied deworming extensively, argue that mass deworming treatment is “a highly cost-effective educational investment and a high-return economic investment even in the absence of any other health benefits from deworming.”

As such, the authors argue, the positive epidemiological and fiscal spillovers of mass treatment are large enough to support the WHO-advocated mass presumptive treatment of children in affected regions of the world, and is significantly less expensive than screening and treatment of only those found to be infected.

Low Cost

Mass deworming is very inexpensive, estimated to cost approximately $0.35 per child per round of treatment, including the cost of delivering the treatment. It is also delivered through the existing school infrastructure and is easily dispensed by the trained teachers. Compare this to the cost of diagnosing a worm infection which requires highly skilled staff and costs 4-10 times that of the treatment itself.

The authors make a compelling comparison: “The vast majority of the 870 million children at risk of worm infections could be treated each year via mass deworming programs at a cost of approximately 300 million dollars a year, which is feasible given current health budgets. The cost of treating them via screened programs would likely be closer to 2 billion dollars annually, if not higher.”

Communities, Not Just Individuals

Additionally, the authors points out, “most studies on deworming in the public health literature have failed to consider the potential for epidemiological externalities from treatment, where treatment can improve outcomes not only for the person treated but also others by reducing the chance of disease transmission.”

In other words, entire communities benefit when the main vectors for disease transmission--children--are regularly treated. There is a “herd effect” for deworming, just as there is for a vaccine.

The authors then detail the significant and rigorously studied educational benefits of mass treatment. We here at Evidence Action have ourselves summarized this ever-growing body of solid evidence that supports mass school-based treatment of children. Rigorous studies in Uganda, Kenya, and India have found that mass deworming results in higher school participation and attendance rates, academic test scores, and other cognitive gains for treated children.

Labor Market And Income Gains

Ahuja and colleagues add to this discussion the significant labor market and income gains as a result of mass deworming treatment. Baird and colleagues in an unpublished 2014 study, compute an annualized internal rate of return--a way to measure the profitability of an investment--of an astounding 32-55% for school-based deworming.

These kinds of returns on investment mean that:

“...policy makers would be warranted in moving ahead with deworming even if they thought its benefits were likely to substantially smaller in their own context.. even if the impact of deworming on school participation were only 1/10th of that estimated by Miguel and Kremer [in 2004], it would still be among the most highly cost effective ways of boosting school participation. Furthermore, labor market effects half as those estimated by Baird et al would be sufficient to generate enough tax revenue to fully cover its costs.”

It’s Good Public Policy

Policy makers, take note to what countries like Kenya, Vietnam, India, and others have already realized: Mass school-based deworming is indeed a ‘best buy’ for countries where worms are endemic. It is not just good educational and health policy but benefits the entire economy.

We at Evidence Action look forward to working with more partners to make these benefits real.