Self-diagnosis as a possible basis for treating urinary schistosomiasis : a study of schoolchildren in a rural area of the United Republic of Tanzania

A questionnaire for schoolchildren about symptoms of urinary schistosomiasis is becoming widely used to identify schools where the prevalence of infection with Schistosoma haematobium is greater than 50%, the threshold for applying mass treatment. This strategy typically leaves many schools without treatment even though some of the children have urinary schistosomiasis and blood in urine. We examined data collected during an evaluation of a school health programme in Tanga Region, the United Republic of Tanzania, to determine whether self-diagnosis could be used as a basis for giving treatment. Over 2300 children in 15 schools were asked by a nurse whether they had kichocho (urinary schistosomiasis) and their answers were compared with the results of tests for visible and occult blood in urine, and microscopy for 5. haematobium eggs. An average of 75% of children were correct in their self-diagnosis (95% confidence interval (CI) = 72-78%), while 3% gave a false-positive diagnosis (95% CI = 2-4%). The remaining 22% gave a false-negative diagnosis (95% CI = 20-25%) and would not have been treated, although most of these children were lightly infected. These proportions were independent of a wide range of prevalence levels (7-77%) and intensity of infection (23-827 eggs per 10 ml of urine). Self-reported schistosomiasis might thus be used to treat children in schools where mass treatment is not applied.