Patterns of infection with Schistosoma haematobium in lakeside resettlement communities at the Oyan Reservoir in Ogun State, south-western Nigeria.

Patterns of infection with Schistosoma haematobium were studied in 1991 and 1992 in two, lakeside, resettlement communities at the newly established Oyan Reservoir in Ogun State, Nigeria. Prevalence and intensity of S. haematobium infection and frequency of haematuria and proteinuria all increased markedly from 1991 to 1992, indicating intensive transmission. This was confirmed in an incidence study. In both years, infection patterns were highly age-dependent, with peaks in those aged 10-14 years. These patterns deviate from those seen during a survey carried out in the same communities in 1988, providing strong evidence that infection had changed from an epidemic to an endemic stage. Although sex, tribe, religion, occupation, and village of residence had little if any effect on infection pattern, the patterns in settled and migrant groups differed considerably. The study provided a thorough elucidation of the complexity and instability of transmission of S. haematobium in a resettlement community characterized by social instability and extensive population movements. Although haematuria was very common, the subjects knew little about its cause.