A Comparative Study of Intradermal Tests and Stool Examination in Epidemiological Surveys on Schistosomiasis Mansoni

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  • Instituto Nacional de Endemias Rurais, Centro de Pesquisas de Belo Horizonte, Brazil

Summary

The relative efficiency of stool examination (Hoffman, Pons and Janer technique) and intradermal tests with cercarial and adult worm antigens for diagnosing Schistosoma mansoni infection was studied in two groups living in an endemic area: a) 454 unselected schoolchildren aged 10 to 15 years and frequently exposed to infection; b) 558 unselected military personnel with only occasional exposures.

In the first group (children), stool examination gave better results than intradermal test. The positivity rate obtained with a single stool examination (65.64%) was slightly higher than that obtained with cutaneous test using cercarial (57.61%) or adult worm antigen (55.07%). In adults, only 24.19% showed S. mansoni eggs after a single stool examination whereas the skin test was positive in 52.87% and 51.43% using cercarial and adult worm antigens, respectively.

Among 289 skin-positive children, 276 (95.50%) were positive for S. mansoni eggs after one or more stool examinations. In adults, of 174 individuals who reacted positively to the skin test but had been negative at the first stool examination, 147 (84.48%) showed parasitological or serological (complement-fixation test) evidence of S. mansoni infection.

Cercarial or adult worm antigens gave similar results in both groups studied.

The need for further studies in different epidemiological circumstances, using skin test and stool examination under standardized conditions in order to evaluate the real efficiency of these methods in epidemiological surveys, is emphasised.

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