Infection and transmission pattern of Schistosoma mansoni in the Managil irrigation scheme, Sudan

The endemicity (prevalence, intensity and incidence) of schistosomiasis mansoni and its patterns of transmission (focality, seasonality) were studied in five villages in the Managil irrigation scheme, Sudan. Marked differences between villages were observed in overall prevalence (33.3%-54.8%), intensity (77.3-135.0 eggs/g faeces), incidence (15.2%-57.9%) and age-related patterns of Schistosoma mansoni infections. Overall, prevalence and intensity of infection peaked in those aged 10-14 years and then declined slowly with increasing age. However, there were second, smaller peaks in both prevalence and intensity of infection in the older males (> 40 years) and, in general, the indices of infection for males exceeded those for females. The infection pattern was influenced by occupation and possibly by having a latrine. Transmission of S. mansoni in the Managil irrigation scheme is highly focal and seasonal, taking place in a few major human-contact sites near villages and peaking during the hot and dry season (April-June). The infection and transmission patterns of S. mansoni in the scheme show great resemblance to those in the neighbouring Gezira irrigation scheme.