Immunofluorescence test on Schistosoma mansoni worm paraffin sections (IgM-IFT) for the study of shistosomiasis transmission in Campinas, Säo Paulo, Brazil

ABSTRACT

The detection of IgM antibodies for Schistosoma mansoni using gut-associated antigens (IgM-IFT) was compared to the parasitological Kato-Katz method for study of the transmission of shistosomiasis in an urban area in Campinas. About 400 school children whose ages ranged from 6 to 18 years were observed for a period of two years. Blood samples on filter paper and fecal samples were collected, at intervals of six months. Serological (IgM-IFT) prevalence rates of 1.2 per cent, 4.3 per cent, 3.6 per cent, 2.9 per cent and 3.4 per cent were obtained in five surveys carried out. S. mansoni eggs were detected in only one child out of the 225 children (0.4 per cent) who were submitted to the Kato-Katz method (three slides for each fecal sample) in the 1st survey. Sixty eight children who submitted five blood samples, one for each survey, were found IFT negative throughout the study. No child was found to be IFT positive in all five surveys, and only four children showed IFT positive results in at least four surveys. Seroconversion from IFT negative to positive was observed from the 1st to the 2nd survey in six children, from the 2nd to the 3rd survey in three children, from the 3rd to the 4th survey in four children, and from the 4th to the 5th survey in two cases. However, confirmation of S. mansoni infection using the fecal examination was not possible in any of the cases. Also, in most of them the IFT result oscillated from negative to positive and vice versa. Our data implied that recent transmission of schistosomiasis in the study area was not possible.