Helminth infections, including soil-transmitted helminths and schistosomiasis, remain one of the most common infections in the world with over 1 billion people infected. These infections cause significant morbidity, particularly in young children, that may last a lifetime, including growth and cognitive stunting. There is an urgent need for the control and elimination of helminth infections from areas of poverty to reduce morbidity in children. Mass drug administration programs were adopted by the World Health Assembly in 2001 and have evolved to provide coverage with multiple anthelmintic medications in a single rapid impact package and more extensive coverage within a community.
Key points
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Soil-transmitted helminths and schistosomiasis are some of the most common infections found in children and adolescents worldwide and cause significant morbidity and chronic disability.
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Current strategies to reduce morbidity associated with soil-transmitted helminths and schistosomiasis include mass drug administration (MDA) and programs of water, sanitation, and hygiene (WASH).
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Although MDA and WASH are reducing the overall prevalence of helminth infections, global elimination remains elusive because of low drug efficacies and reinfection.
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Alternative strategies, including improved diagnostics, improved worm prevalence and resistance monitoring, new anthelmintics diagnostics, therapies, and vaccines, are required.
Introduction
Helminth infections, including hookworm ( Necator americanus , Ancylostoma duedenale ), roundworm ( Ascaris lumbricoides ), and whipworm ( Trichuris trichiura ), collectively known as intestinal (or soil) transmitted helminths, as well as schistosomiasis, are among the most common infections found in children worldwide, infecting almost 2 billion people ( Table 1 ). Although intestinal helminth infections and schistosomiasis are not the only major parasites affecting children, their overwhelming numbers in terms of pediatric cases globally requires special attention. New estimates from the Global Burden of Disease Study 2015 indicate that together these helminth infections resulted in more than 6 million disability-adjusted life-years (DALYs), a number roughly equivalent to the DALYs caused by measles, Haemophilus influenzae type B meningitis, or other better-known pediatric conditions. However, even these DALY estimates may represent “low-ball” figures based on revised estimates of more than 4 million DALYs from hookworm alone. Thus, although intestinal helminth infections are not leading causes of death, they are profoundly important causes of childhood disability and even future economic disrupters, with calculated adverse effects on future wage earning. Overwhelmingly, these worms affect children living in extreme poverty, particularly those living in rural communities or urban communities that lack adequate water, sanitation, and hygiene (WASH). Contrary to previous assumptions, helminths and other neglected tropical diseases are not restricted exclusively to resource-limited countries. For some worm infections, there is a significant burden of disease found in poor communities living in countries with robust economies, including areas of the United States.
| Major Human Species | Estimated Prevalence (Cases) | DALYs (Millions) | Deaths | References | |
|---|---|---|---|---|---|
| Roundworm (Ascariasis) | Ascaris lumbricoides | 761.9 million | 1.075 | 2700 | |
| Whipworm (Trichuriasis) | T trichiura | 463.7 million | 0.653 | None specified | |
| Hookworm | N americanus and Ancylostoma sp | 428.2 million | 1.758 | None specified | |
| Blood Fluke (Schistosomiasis) | S haematobium , S mansoni | 252.3 million | 2.613 | 4400 | |
| Total | >1.9 billion | 6.096 | 7100 | — |
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