Combination of Kato–Katz faecal examinations and ELISA to improve accuracy of diagnosis of intestinal schistosomiasis in a low-endemic setting in Brazil

da Frota, Sabrina Menezes, Carneiro, Teiliane Rodrigues, Queiroz, José Ajax Nogueira, Alencar, Lúcia Maria, Heukelbach, Jorg, and Bezerra, Fernando Schemelzer Moraes (2011) Combination of Kato–Katz faecal examinations and ELISA to improve accuracy of diagnosis of intestinal schistosomiasis in a low-endemic setting in Brazil. Acta Tropica, 120 (Supp 1). S138-S141.

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Considering the decrease of disease burden caused by intestinal schistosomiasis in many endemic settings, more sensitive diagnostic methods are needed to plan and monitor control measures. We conducted a cross-sectional survey in a rural community in northeast Brazil (317 inhabitants). A combined approach including repeated faecal examinations and ELISA testing was applied. In a first round, single stool samples were collected from 305 (96.2%) participants. Three Kato–Katz (KK) smears were prepared from each sample, and IgG ELISA was performed from serum samples. In the 85 cases of negative KK smears, but positive ELISA results, three additional faecal samples were collected in a second round, and another five KK smears prepared. In the first round of KK analysis, 11/287 (3.8%; 95% confidence interval; 1.92–6.75) were positive. After examining up to eight smears per individual (second round), prevalence of schistosomiasis increased to 8.7% (95% confidence interval: 5.9–12.5). In total, 96/287 (33.4%, 95% confidence interval: 28.0–39.2) samples were positive by ELISA testing. There were no false negative ELISA results. Specificity, positive and negative predictive values of ELISA as compared to up to eight KK smears from three stool samples (reference diagnosis) were 72.9%, 26.0% and 100%, respectively. A single KK smear detected only 12% of the 25 infections; this increased to 44% (three smears, one stool sample), 84% (five smears, three stool samples) and 96% (six smears, four stool samples). We conclude that in low-endemic areas in Brazil the use of KK continues being an important tool. The additional benefit of preparing more than six KK smears from repeated stool samples is negligible. ELISA may be useful for screening populations, with subsequent confirmation of diagnosis by KK or other more sensitive, but highly specific methods.

Item ID: 21714
Item Type: Article (Refereed Research - C1)
Keywords: Brazil, diagnosis, ELISA, Kato-Katz, Schistosoma mansoni, schistosomiasis
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This article is published under the CC-BY-NC-ND 3.0 license.

ISSN: 1873-6254
Date Deposited: 25 Apr 2012 22:03
FoR Codes: 11 MEDICAL AND HEALTH SCIENCES > 1103 Clinical Sciences > 110309 Infectious Diseases @ 50%
11 MEDICAL AND HEALTH SCIENCES > 1117 Public Health and Health Services > 111799 Public Health and Health Services not elsewhere classified @ 50%
SEO Codes: 92 HEALTH > 9201 Clinical Health (Organs, Diseases and Abnormal Conditions) > 920109 Infectious Diseases @ 30%
92 HEALTH > 9204 Public Health (excl. Specific Population Health) > 920499 Public Health (excl. Specific Population Health) not elsewhere classified @ 30%
92 HEALTH > 9202 Health and Support Services > 920203 Diagnostic Methods @ 40%
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