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Title: IMPLICATIONS OF INTRA- AND INTER-SPECIMEN FECAL EGG COUNT VARIATIONS IN DIAGNOSING Schistosoma mansoni INFECTION BY THE KATO-KATZ METHOD, IN WORKIE MADO VILLAGE, KEMISE, NORTH-EAST ETHIOPIA
Authors: Manyawkal, Bireda
Advisors: Nega Berhe(Dr.)
Keywords: Schistosoma mansoni
Kato-Katz technique
egg count
intra-specimen
intra-specimen
Workie Mado village
Ethiopia
Copyright: Jun-2011
Date Added: 4-Jul-2012
Publisher: Addis Ababa University
Abstract: Examination of stool specimens by the Kato–Katz (K–K) technique has been a standard method for field diagnosis of intestinal Schistosomiasis. However, it has been debated that this technique has low diagnostic sensitivity due to intra- and inter-specimen fecal egg count variation. The relative contribution of these two sources of variation among 107 community members of Workie Mado village, northeast Ethiopia, which is known for its high endemicity of S. mansoni infection was quantified. The diagnostic yield of examining one, three, or five Kato–Katz thick smears prepared from one stool specimen, using 41.7 mg templates was compared. In a subset of 11 volunteers, who had no demonstrable eggs in their first five K–K thick smears, the advantage of examining two additional triplet K–K thick smears from stool specimens, taken in two subsequent days was assessed. The overall prevalence estimates of infections increased with increasing number of slides examined. Prevalence of S. mansoni infection based on single, triplet, and quintet K–K thick smears was 62.6%, 75.7% and 84.1%, respectively. Cumulative prevalence obtained with two additional triplet Kato–Katz thick smears from 2nd and 3rd day stool specimens was 85.0% and 86.0%, which is not significantly different from quintet measurement. Compared to quintet K–K thick smears, single K–K thick smear missed 46.8%, 2.6% and 0% of subjects with light, moderate and heavy infections, respectively, while triplet K-K thick smears missed 19.1% of light infections and 0% of moderate and heavy infections. We conclude that diagnostic sensitivity in such high transmission areas can be maximized by using quintet K-K thick smears from one stool specimen to reduce the number of missing lightly infected individuals, and thereby examining smear-negative individuals with additional triplet K-K thick smears, from subsequent day stool specimens. Moreover, examining only one stool specimen with quintet K-K thick smears can also make reasonable estimates of S. mansoni infection intensity, and it would be more feasible and less expensive approach than day-to-day examination of individuals in communities.
Description: A thesis submitted to the School of Graduate Studies: In partial fulfillment of the requirements for the Degree of Master of Science in Biology (Biomedical Sciences)
URI: http://hdl.handle.net/123456789/3272
Appears in:Thesis - Biology

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