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USAID's NTD Program
USAID's NTD Program

Schistosomiasis

Epidemiology

  Photo of a person's swollen abdomen.
  Source: Andrea Peterson

Schistosomiasis infection is acquired in childhood. Infection increases in prevalence and intensity with age, culminating in school-age children. Furthermore, children also suffer the most consequences due to the disease, especially poor growth and impaired cognitive function.1 In older people, there is a drastic decline in intensity but not in prevalence. Individuals become infected with this disease while bathing or swimming in water contaminated with the parasite. However, schistosomiasis also can be transmitted simply through contact with contaminated water while performing daily chores, such as washing laundry, fetching water, and herding animals.2 Thus, patterns of sanitation, water supply, and human water use, are crucial elements in determining the risk of infection.3 Additionally, the geographic distribution of the various species of Schistosoma is fully dependent on the distribution of the intermediate hosts (snails) species.

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References

  1. Nokes, C., Grantham-McGregor, S.M., Sawyer, A.W., Cooper, E.S., Bundy, D.A.P. Parasitic helminth infection and cognitive function in school children (1992). Proceedings of the Royal Society of London 247, 77-81.
  2. Asaolu SO, Ofoezie IE. The role of health education and sanitation in the control of helminth infections. Acta Trop 2003; 86: 283-94
  3. Rudan, I., Lawn, J., Cousens, S., Rowe, A. K., Boschi-Pinto, C., Tomaskovic, L., Mendoza, W., Lanata, C. F., Roca-Feltrer, A., Carneiro, I., et al. (2005) Lancet 365,2031-2040.