One of the major causes of childhood morbidity in Africa is Schistosomiasis which adversely effects childrens’ nutrition, education, development and productivity. In adults, the study of schistosomiasis may be particularly important given the possibility of HIV infection through female genital schistosomiasis, its possible impact on clinical progression of HIV, decreased host response to tuberculosis infection and efficacy of future HIV vaccination trials/programmes. However, despite the fact that historically levels of infection have been very high in this area and that treatment is cheap, safe and effective, there has been little research into the levels of infection in this area in the last decade.
Research questions
· What is the prevalence and intensity of S. haematobium infection in all grade 5 and 6 pupils in schools in the DSA?
· Are S. haematobium infections randomly distributed in space or do they cluster in certain areas?
· What are the key environmental, individual, social, community and behavioural risk factors of infection?
· Are there any gender differences in pathways of infection?
· What do the answers to the above questions mean for intervention?
Fit of the research question within the AC portfolio/strategic plan
The study relates very well to the fourth research question of the Africa Centre’s scientific strategy which is: How can the health of children and adults in an environment challenged by HIV and other adversities be improved?
Data sources and methods
The Africa Centre’s school-based schistosomiasis survey was conducted between March 2007 and November 2008 among 2,105 consenting Grade 5 and 6 pupils present on the day of testing at all 33 primary schools in the study area. All pupils found to be infected with S. haematobium were offered treatment with praziquantel. The study use spatial analytical methods and GIS technology in combination with satellite-derived imagery to understand patterns of infection among primary school children in the study population.
Findings/expected findings
The overall prevalence of S. haematobium in the cohort was 16.8% (95 CI, 15.2 – 18.4%) and prevalence of heavy infection (>50 eggs/cl urine) = 9.5% (95 CI, 8.2-10.7). Large geographical heterogeneities in infection across the DSA (0 – 80%) were detected and a spatial clustering statistic identified four primary sites of transmission around infected water bodies. Overall, boys were twice as likely to be infected in comparison to girls. Controlling for multiple environmental determinants of infection, higher SES class, urban residence and piped water in the household were protective for girls but not for boys. Living in an area with high piped water coverage (mean coverage over 5 years) was strongly protective for both sexes but the protective effect was twice as strong for girls as for boys.
Policy implications
In line with WHO recommendations, annual mass treatment of primary school children should be carried out in 20% of schools in the area (prevalence > 30%), whilst 40% of schools should be mass-treated every other year (prevalence of 10-30%). The remaining schools need only have intermittent treatment programmes (prevalence <10%). The study is the first of its kind to be conducted in rural South African population after rapid roll-out of safe drinking water. Levels of infection remain comparatively high given that >80% of the population now have access to safe drinking water. The results suggest that the provision of piped water in the study area has significantly reduced contact girls have with infected water by reducing the need to for water collection from unsafe sources. The large protective impact of coverage of piped water at a community level for both sexes suggests that provision of safe accessible water has resulted in a decrease in the overall parasite reservoir in these areas to the benefit of the entire community. The cohort constitutes an important group of children with which to monitor rates of HIV acquisition and disease progression (measured as part of the routine HIV surveillance) in the coming years.