Abstract
The frequency of mass drug administration for schistosomiasis is determined by the community prevalence. This study aimed to assess the influence of seasonality on community prevalence measured by urine microscopy. A cross-sectional study was conducted in primary schools in rural KwaZulu-Natal, South Africa. We collected three urine samples from 622 girls aged 10-12 years, of which 33.9 % were Schistosoma haematobium positive. The measured prevalence was higher just after the high-transmission season (hot season) compared to in the end of the low-transmission season (cool season) (adjusted OR 5.20, 95% CI 4.83 -- 8.33). The log-transformed egg counts in positive cases showed continuous decrease throughout the low-transmission season of 7.4 eggs / mL per month. Our findings show that in rural South Africa, the community prevalence measured in school-aged children is not constant throughout the year. This may be due to a gradual reduction in worm burden after the transmission season. In order to make decisions about eligibility for mass-treatment, urines should be collected shortly after the hottest season in our study area.