Urinary schistosomiasis in schoolchildren in Dar-es-Salaam, Tanzania, and the factors influencing its transmission

The prevalence of urinary schistosomiasis among the schoolchildren living i n Kigogo administrative ward of the Kinondoni district of Dar-es-Salaam cit y, Tanzania, and the factors influencing the transmission of the causative agent, Schistosoma haematobium, were investigated in a cross-sectional stud y. The estimate of overall prevalence, based on microscopical examination o f a single urine sample/subject, was 47.6%. Compared with the girls, the bo ys were more likely to be excreting schistosome eggs (54.6% v. 40.8%; P = 0 .004) and had, in general, higher intensities of infection (54 v. 38 eggs/1 0 ml urine; P = 0.001). The children aged 10-14 years had higher prevalence s and intensities of infection than those in the younger or older age-group studied. The sensitivity of micro-haematuria as an indicator of infection (compared with the microscopical examination of single urine samples) was 8 4.3% overall, reaching 92% among the children excreting greater than or equ al to 50 eggs/10 ml urine. The corresponding positive and negative predicti ve values were 77% and 84%, respectively. The sensitivity, specificity and positive and negative predictive values of the history of haematuria as an indirect screening technique for S. haematobium were 60.4%, 72.7%, 67% and 67%, respectively. Recreational activities such as bathing, swimming and pl aying in the water were the most frequent activities attracting children to water bodies and carried the highest risks of infection with S. haematobiu m. Knowledge about the disease, especially on the symptoms and mode of tran smission, was generally good but the methods of prevention were inadequatel y known. Chemotherapy to control urinary schistosomiasis in schoolchildren is recommended; infected children may be identified on the basis of haematu ria, detected using questionnaires or reagent strips. Additional health edu cation, to heighten awareness of the disease and its prevention, would also be beneficial.