Screening of Tanzanian women of childbearing age for urinary schistosomiasis: validity of urine reagent strip readings and self-reported symptoms

The screening of women of childbearing age for haematuria, leukocyturia and proteinuria to detect urinary schistosomiasis can be confounded by several factors such as menstruation, pregnancy and genitourinary infections. We t herefore undertook a study in an area endemic for Schistosoma haematobium i n the United Republic of Tanzania to carry out the following: assess the se nsitivity, specificity and predictive values - in women of childbearing age - of indirect indicators of urinary schistosomiasis, as measured by urine reagent strip readings; assess the predictive values of self-reported sympt oms; and finally to estimate the morbidity attributable to S. haematobium. A total of 303 women (128 and 175, respectively, living in high- and low-ri sk sites) participated in the study. Haematuria was more frequent among wom en excreting S. haematobium eggs than among those who did not (65% versus 3 2%). The predictive potential of all indirect disease markers was poor in t he highly endemic site, while in the sites with low endemicity the negative predictive values were high. Among infected women, 54% of haematuria could be attributed to S. haematobium, but for patients with more than 10 eggs/1 0 ml the attributable fraction rose to 70%. Symptoms of "bloody urine" and "pain while urinating" were recalled significantly more often by women livi ng in the highly endemic site. On a population level, one-third of the self -reported cases with bloody urine could be attributed to urinary schistosom iasis. Screening of women of childbearing age for urinary schistosomiasis using ur ine reagent strips can be biased in two directions. The prevalence of S. ha ematobium will be overestimated ii other causes of haematuria, such as repr oductive tract infections, are highly endemic. On the other hand, women wit h light or very light infections will be missed and will not be treated. Th is is of concern because genital schistosomiasis, a possible risk factor fo r the transmission of HIV, occurs among women even with light infections.