Anti-filarial IgG4 in men and women living in Brugia malayiendemic areas

To assess whether antifilarial IgG4 can be used to study various epidemiolo gical facets of: filarial infections, we studied this isotype in 238 indivi duals resident in areas endemic for brugian filariasis, focusing on the dif ferences between men and women. In the study area, the prevalence of microf ilariae was 6.7% and the prevalence of antifilarial IgG4 was 49.2%. All mic rofilariae carriers were positive for antifilarial IgG4, whereas a proporti on of the endemic normals (94/208) and elephantiasis patients (7/14) had Ig G4 antibodies to filarial antigens. Data were analysed as a function of gen der in distinct clinical groups and stratified for age. The prevalence of m icrofilariae was higher in males in all age groups, as reflected in signifi cantly higher antifilarial IgG4 antibody levels compared to females. The pr evalence of IgG4 increased to reach a plateau at the age of 30 years in bot h males and females. These results indicate that antifilarial IgG4 antibodi es can reflect the differences in the extent of infection in males and fema les as measured by microfilarial counts, and that this parameter can be use d for epidemiological assessments of filarial infection.