Schistosomiasis: large-scale treatment decreases prevalence by 60% among school-aged children

Researchers have found that treating school-aged children periodically with praziquantel has decreased the prevalence of schistosomiasis (bilharzia) in sub-Saharan Africa by almost 60% during the past 20 years.

“The decrease in prevalence is related to the scaling up of preventive chemotherapy, as well as factors such as economic and social development on the African continent including greater access to clean water and sanitation,” said Penelope Vounatsou, Head, Biostatistics unit, Swiss Tropical and Public Health Institute. “These findings are encouraging that we are on the right track to eliminating this disease.”

Mass treatment of at-risk groups with priority focus on school-aged children has been the mainstay of the global schistosomiasis programme of the World Health Organization (WHO). The strategy aims to reduce the prevalence of the disease through periodic treatment of affected populations and covers all at-risk groups regularly.

“The study highlights the effectiveness of the WHO-recommended strategy in treating school-aged children periodically,” said Dr Amadou Garba Djirmay, Medical Officer, WHO Department of Control of Neglected Tropical Diseases. “By working in an integrated manner across sectors as highlighted in the new road map,¹ we are confident we can achieve the goal of elimination of schistosomiasis as a public health problem.”

Making praziquantel available to all at-risk groups, developing a paediatric formulation to include preschool-aged children in mass treatment campaigns, and implementing integrated strategies in collaboration with water, sanitation and hygiene, snail control, education and awareness-raising can accelerate progress.

The spatiotemporal modelling study was led by the Swiss Tropical and Public Health Institute (also a WHO collaborating centre) in collaboration with WHO, the University of Basel and partners. It was funded by the European Research Council and WHO.

Effect of preventive chemotherapy with praziquantel on schistosomiasis among school-aged children in sub-Saharan Africa: a spatiotemporal modelling study was published today in the Lancet Infectious Diseases. It analyses cross-sectional survey data of school-aged children (aged 5–14 years) in 44 countries across sub-Saharan Africa. Models were used with data on both Schistosoma haematobium and S. mansoni at three different time periods (2000-2010, 2011-2014 and 2015-2019). The study could potentially assist policy makers to plan their future schistosomiasis control strategies.