Mass treatment at schools takes places once every six months, one year or two years, depending on the prevalence of worm infections. The World Health Organization recommends mass treatment of all school-age children where there is prevalence of schistosomiasis, and where prevalence is above 20% for STH. This is because the cost of treating a worm infection is less than the cost of the diagnostic test and because the treatment is safe even when taken by a child who is not infected. The safe nature of this procedure also means teachers can be trained to deworm children.

All school-age children are encouraged to come to school on deworming day, where their name and age is recorded and their height and weight (where possible) is measured before being treated. The deworming tablets are administered orally, and only a few people will experience side effects, such as transient abdominal pain and diarrhea, due to the passing of the worms.

Due to rapid reinfection in endemic areas, children need to be treated regularly. Programs that improve sanitation and hygiene support deworming by reducing transmission, and all three measures are vital to control worm infections.

To learn more about how school-based deworming works, please visit our section for implementers.