Longitudinal analysis of antigen specific response in individuals with Schistosoma mansoni infection in an endemic area of Minas Gerais, Brazil

Immunoepidemiologic studies have shown a relationship between IgE and IgG4 antibodies with age and with resistance and susceptibility to infection. It is believed that the IgE and IgG4 responses to soluble egg antigen (SEA) can be used for serological analysis of infection and post-treatment status. This study aimed to evaluate the association between Schistosoma mansoni infection and anti-SEA IgG4 and IgE reactivities, and determine whether these reactivities could be used as biomarkers of infection. Between 2001 and 2009, a longitudinal study was performed in which parasitologic and blood specimens and socioeconomic and water-contact information were collected from 127 individuals. All patients positive for S. mansoni infection were treated. Schistosomiasis prevalence and the geometric mean of the egg count in 2001 were 59 and 61.05, respectively, decreasing to 26.8 and 8.78 in 2009. IgG4 anti-SEA reactivity in infected individuals was significantly higher than that in uninfected individuals at all time points. Analysis of receiver-operating characteristic (ROC) area showed that the IgG4 anti-SEA antibodies were able to predict infection by S. mansoni at each time point. IgG4 anti-SEA reactivity can be used as a biomarker for immune monitoring of the presence of infection with S. mansoni in endemic areas.