Immunoglobulin evolution and associated factors with intestinal schistosomiasis after treatment in rural Burkina Faso

The performance of specific antibodies in a post-chemotherapy situation remains a controversial issue. Thus the study aims to investigate the variations of different immunoglobulins, IgG, IgG subclasses, IgM and IgA against Schistosoma mansoni soluble eggs antigens post-treatment and their correlation with eggs excretion. A longitudinal study was conducted on 928 participants over 5 years of age from February 2007 to March 2008 in “Vallee du Kou” in Burkina Faso, a rural area where S. mansoni is endemic. At the inclusion and during follow-up visits (post 1.5, 3, 6 and 12 months), stools and blood samples were examined for Schistosome eggs obtained from stools  by the Kato-Katz test method and serum antibodies (IgM, IgA, IgG, IgG1, IgG2, IgG3, IgG4) obtained from blood by ELISA targeting the antigens of schistosome eggs. Subjects who were stool-egg-positive were treated with praziquantel in a single oral dose of 40 mg/kg. The overall prevalence of S. mansoni infection was 23.27% (216/928) with 77.32% (167/216) having a light intensity of infection. Factors associated with parasite eggs load were IgA, IgG1 and IgG4 titres. During each visit, each increase in IgA titre of 1 unit was associated with a significant reduction in parasite egg load of 50 eggs (p <0.002). The increase in IgG1 and IgG4 titres by 1 unit was associated with significant increases in the parasite egg count of 21 and 32, respectively. IgG1, IgG2 and IgG4 titres decreased significantly during the follow-up time (p<0.0001). In contrast, the titre of IgG3 increased significantly (p=<0.0001). This study showed that IgA, IgG1 and IgG4 are associated with decrease in parasite egg loads in stool and could be a good marker for treatment efficacy. Key words: Immunoglobulins, Schistosoma mansoni, eggs, praziquantel, ELISA, kato-katz, Burkina Faso.