More than one-in-three people in the world, largely in low- and middle-income countries, are affected by diseases caused by parasitic worms, namely helminthiasis, transmitted by contact with contaminated soil, and schistosomiasis, which infects people through water sources. International groups, such as the World Health Organization, have recommended mass deworming campaigns targeting children in the hopes of limiting the impact of worm infections on children’s growth, educational achievement, cognition, school attendance and quality of life.
A new study led by Vivian Welch, who is a clinical investigator at the Bruyère Research Institute and assistant professor at the University of Ottawa’s School of Epidemiology, Public Health and Preventive Medicine, has found that mass deworming campaigns appear to have few benefits for children’s welfare. Welch and her colleagues conducted a systematic review with Campbell Collaboration, a non-profit organization that supports the production and use of systematic reviews to inform evidence-based policy. The review included 65 short-term studies on 1,092,120 children, along with four long-term studies conducted after 90,000 children were subject to mass deworming programs.
The data shows that while targeted treatment may have positive effects on individual children, at the population level, mass deworming campaigns have little effect on overall health, school attendance and welfare. This could be explained by the high levels of re-infection that occur after deworming campaigns due to sanitation issues and poor living conditions.
Many international organizations currently promote mass deworming campaigns as one of the most cost-effective ways of increasing school attendance. These campaigns involve administering de-worming medication to all children because of the prohibitive cost of screening each child for worm infections, which can be difficult to diagnose.
“Our findings reinforce the case against mass deworming alone for improving child welfare, and suggest the need to consider investment in policies that address the causes of worm infestations, such as poor sanitation, poverty and living conditions,” says Dr. Welch.
Dr. Welch notes that data from the systematic review of deworming campaigns could help identify which communities and subgroups of the population could benefit most from deworming. “We feel that it’s important to assess whether we can identify children or settings which are likely to benefit from mass deworming,” says Dr. Welch. “We can achieve this by looking at information that can easily be collected or is already available in these areas, such as nutrition, sanitation and hygiene practices, and the prevalence and intensity of worm infections.”
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