Schistosomiasis mansoni in Bananal (State of Säo Paulo, Brazil). III. Seroepidemiological studies in the Palha District

RESUMO

The Palha district, municipality of Bananal, State of Säo Paulo, Brazil, had 10.3 percent cases of Schistosoma mansoni diagnosed from 1994 to 2000 by coproscopy about three times the municipality average. The immunofluorescent antibody test was used to assess gut-associated IgM antibody titers of samples from 452 inhabitants. It disclosed 129 (28.5 percent) positive cases. Subjects were classified according to age, sex, birthplace, and period of residence. Titers varied from 8 to 4,096 (geometric mean 170.2). Seropositives were aged from 6 to 69 years (average 24.5), 75 percent of them aged 34 or less, predominantly males (78 or 60.5 percent). Of all subjects, 65.7 percent were born and had been living in Bananal since; 24.2 percent came from neighboring municipalities and are residing in Bananal from two months to 89 years (average 22.7 years). Further Kato-Katz coproscopy from 97 seropositives (geometric mean titer, 619) revealed S. mansoni eggs in 11 subjects (11.3 percent). Serology was deemed useful in screening subjects to be further investigated by coproscopy, considering that blood collection had better acceptance than supplying fecal samples. Higher than average serological titers may indicate new cases in endemic areas. Longitudinal studies associated with epidemiological investigation, including titer evolution are advised, as isolated data are difficult to interpret