[Preliminary evaluation of usable indicators during a control program for urinary bilharziosis in Niger]

The performance of several indirect screening tests was evaluated during the start-up phase of a urinary schistosomiasis control program in Niger. Urine tests were carried out on a total of 354 children attending 3 primary schools on five consecutive days. Tests included filtration of 10 ml of urine, search for microscopic hematuria using reagent strips, and gross examination of urine. In addition a questionnaire was administered on the first day to identify signs of dysuria and hematuria. Repeat testing had a strong effect on the epidemiological profile of urinary schistosomiasis in the 3 schools. Although day-to-day counts varied greatly, egg excretion could be considered as high in all infected subjects. The screening sensitivity of urine filtration was low when the level of endemicity was moderate (up to 55 p. 100). Microscopic hematuria was common. However the sensitivity of this method was overestimated in comparison with urine filtration alone and use of reagent strips can be inconvenient. Using carefully defined diagnostic criteria, gross examination of urine was as effective as urine filtration and easier to perform. The value of the questionnaire for evaluation of morbidity was low despite relatively good performance of the diagnostic techniques. The children's responses concerning hematuria were not objective and questions concerning dysuria were poorly understood and time-consuming. In the next phase of study, these findings will be validated by ultrasound imaging.