The reliability of a questionnaire-based self-diagnosis in estimating the prevalence of schistosoma haematobium in Kwale District
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Schistosomiasis is a chronic debilitating parasitic infection. It is currently estimated, that 200 million people are infected by this worlds most prevalent parasitic disease and 600million are at risk of infection. It is endemic in 76 countries, 85% of all cases and virtually all of the most severe are in African countries. Not withstanding the situation in sub Sahara Africa over the past 20 years schistosomiasis control has been successful in other geographical regions especially due to reduction of morbidity by chemotherapy. In Kenya the distribution is along the lake Victoria, in central, eastern and coast provinces. In most cases the occurrence of schistosomiasis is in areas where irrigation and settlement schemes as well as water development projects have been established. Prevalence of up to 80% and above have been recorded among primary school children in endemic areas of the country. Routine diagnosis of urinary schistosomiasis is by microscopic or chemical reagent strips. Both methods are expensive and are not available at the peripheral health units in the country where the disease is endemic. Before treatment the prevalence of schistosomiasis by microscopic method was 79.9% f I while by reagent strip haematuria was 77.9 % and proteinuria 76.9%. Self diagnosis: . prevalence was 73.3%. Sensitivity and specificity of the self diagnosis was 84.8% and:' 71.1% while positive and negative predictive values were 92.4% and 55.7% respectively. After treatment the prevalence of schistosomiasis by microscopic" method was 27.1% while by reagent strip haematuria was 18.2 % and proteinuria 22.6%. Self diagnosis prevalence was 43.4%. The aim of this study was to assess the reliability of self-diagnosis through a t questionnaire to estimate the prevalence of urinary schistosomiasis before and after I treatment among 470 boys in 4 primary schools in Kinango division ofKwale district. These results suggest that self-diagnosis is a reliable method of assessing prevalence before treatment and that despite the infection in terms of egg count being reduced by treatment, morbidity continued beyond three months after treatment and therefore self diagnosis is a better tool to assess morbidity as well.