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IgM-Immunofluorescence Test as a Diagnostic Tool for Epidemiologic Studies of Schistosomiasis in Low Endemic Areas
Herminia Yohko Kanamura; Rita Maria da Silva; Silvia Gabriel Chiodelli; Carmen Moreno Glasser & Luiz Candido de Souza Dias
Abstract
The high sensitivity and the ability to diagnose schistosomiasis
in a very early phase after infection have indicated the detection of IgM
antibodies to Schistosoma mansoni gut antigens by the immunofluorescence
test (IgM-IFT) as a useful serological test for epidemiological studies
in low endemic areas. When applied in a follow-up study for two years, higher
rates of seroconversion from IFT negative to positive were observed during
the summer months, suggesting seasonal transmission of schistosomiasis in
the rural area of the municipality of Itariri (São Paulo, Brazil).
In each survey, blood samples from about 600 schoolchildren were collected
on filter paper and submitted to IgM-IFT. When the blood samples were classified
for the IgM antibody levels, according to the intensity of fluorescent reaction
observed at fluorescence microscopy, and correlated to the egg counts in
the Kato-Katz positive patients, no association was observed. This observation
might suggest that the intensity of fluorescence observed in the IgM-IFT,
as an indicator of IgM antibody levels, could not be an useful seroepidemiological
marker for classifying areas of low endemicity according to degrees of infection.
Keywords
Schistosoma mansoni  - IgM - IFT - low endemic area - seroepidemiology
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