Schistosomiasis: number of people treated worldwide in 2014

Overview

Schistosomiasis is caused by blood flukes (trematodes) of the genus Schistosoma. Six species infect humans: S. guineensis, S. haematobium, S. intercalatum, S. japonicum, S. mansoni and S. mekongi, of which S. haematobium and S. mansoni are the predominant causes of disease. Schistosomiasis occurs in intestinal and urogenital forms. Transmission of infection begins when human excreta containing parasite eggs reach fresh water bodies and hatched larvae infect susceptible snail hosts. Parasites undergo asexual multiplication in snails and another larval stage, infective to humans, is released into water. People are infected during domestic, occupational and recreational water contact.

The distribution of schistosomiasis is focal, as transmission depends on specific snail hosts and particular human activities, with endemicity continuously changing as a result of environmental alteration, water development schemes, migration, control interventions and snail host distribution.

This report presents data on the number of people treated for schistosomiasis globally, and by WHO Region, in 2014. The estimated total number of people requiring treatment for schistosomiasis in 2014 was 258 875 452, of whom 123 329 536 (47.6%) were school-age children (5–14 years of age). In 2014, 91.4% of the people estimated to require treatment for schistosomiasis lived in the African Region. Reporting on treatments shows progress in implementation of control to prevent and/or reduce morbidity. Other parameters are required to assess comprehensive schistosomiasis control programmes that include access to water, sanitation, hygiene education, and snail control.