Ethiopian Journal of Health Sciences

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Diagnostic efficacy of indirect hemagglutination test inrelation to Kato method for diagnosis of Schistosomiasis mansoni

B Erk


BACKGROUND: Sensitive and specific diagnostic tools are very central to decide on individual case management and at all stages of control programs in schistosomiasis. This study was undertaken to assess the diagnostic efficacy of a commercial indirect hemagglutination test in detection of schistosomiasis mansoni in relation to the Kato method.
METHODS: In a cross sectional study undertaken in May 2004, blood and stool samples were collected from 134 children in Bochesa Elementary School around Ziway town. The stool specimens were processed using Kato method and examined microscopically. Eggs per gram of stool were computed as geometric mean. Sera were separated and transported to laboratory. Indirect hemagglutination test was performed following procedures given by the manufacturers. The diagnostic performance of indirect hemagglutination was evaluated using Kato as the gold standard.
RESULTS: The overall prevalence of intestinal schistosomiasis as detected by indirect hemagglutination test and Kato method was 74.6% and % 76.1%, respectively (p = 0.284). The respective prevalence of infection as detected by indirect hemagglutination tests and Kato method among male students was 82.6% and 85.0 % where as the corresponding value for females was 60.4% for both indirect hemagglutination test and Kato method. The sensitivity and specificity of the indirect hemagglutination test were 83% and 53%, the positive predictive value being 85%. However, there was discrepancy between indirect hemagglutination test and Kato method in
determining the intensity of infection. Only 5% of the examined individuals had light infection with a cut off titer of 81: 256 as detected by IHA test while 95% of the cases had heavy infection with a cut off titer of ; 1: 512. On the other hand, the Kato method revealed that 18.5% of the children was heavily infected (;400 epg) while 81.5 % of them had light to moderate infection (8399 epg).
CONCLUSIONS: The present findings indicate that indirect hemagglutination test can be used as an adjunct to the Kato method for field use in the diagnosis of intestinal chistosomiasis. Nevertheless, the fact that the test is expensive and also not a rapid test may limit its use in the field for epidemiological application.
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