Schistosomiasis remains a worldwide public health problem, especially in sub-Saharan Africa. The World Health Organization targets the goal for its elimination as a public health problem in the... Show moreSchistosomiasis remains a worldwide public health problem, especially in sub-Saharan Africa. The World Health Organization targets the goal for its elimination as a public health problem in the 2030 Neglected Tropical Diseases (NTDs) Roadmap. Concerted action and agile responses to challenges will be necessary to achieve the targets. Better diagnostic tests can accelerate progress towards the elimination by monitoring disease trends and evaluating the effectiveness of interventions; however, current examinations such as Kato-Katz technique are of limited power to detect light-intensity infections. The point-of-care circulating cathodic antigen (POC-CCA) test shows a higher sensitivity compared to the reference standard, Kato-Katz technique, but it still lacks sufficient sensitivity with low infection intensity. In this study, we examined antibody reactions against recombinant protein antigens; Schistosoma mansoni serine protease-inhibitor (SmSerpin) and RP26, by enzyme-linked immunosorbent assay (ELISA) in plasma samples with light-intensity infection. The sensitivity using the cocktail antigen of recombinant SmSerpin and RP26 showed 83.7%. The sensitivity using S. mansoni soluble egg antigen (SmSEA) was 90.8%, but it showed poor specificity (29.7%), while the cocktail antigen presented improved specificity (61.4%). We conclude that antibody detection to the SmSerpin and RP26 protein antigens is effective to detect S. mansoni light-intensity infections. Our study indicates the potential of detecting antibody against recombinant protein antigens to monitor the transmission of schistosomiasis in low endemicity contexts. Show less
The work presented in this thesis is an investigation of the immune responses induced by chronic schistosomiasis in Gabonese schoolchildren. By investigating concurrently various aspects of the... Show moreThe work presented in this thesis is an investigation of the immune responses induced by chronic schistosomiasis in Gabonese schoolchildren. By investigating concurrently various aspects of the immune response, including innate, adaptive and regulatory responses, we are able to gain a more in-depth understanding of the dynamic changes brought about by infection. Through a number of cross-sectional and longitudinal studies we show that S. haematobium infection induces increased frequencies of regulatory B (Breg) and T (Treg) cell subsets which are associated with increased levels of IL-10 and adaptive immune hypo-responsiveness. Anti-schistosome treatment results in the reduction of regulatory subsets, an increase in effector T cells and alleviation of suppressed antigen immune responses. By showing that Treg cells are linked to effector responses and that schistosomes can induce Breg cells, the scene is set for future studies to determine antigen specificity of these cells as well as ways to control their activity. As regulatory responses have been shown to be not only important in chronic infectious disease, but also in chronic inflammatory diseases the knowledge gained here may be of substantial value to the health of those living in both low- to middle-income countries as well as high-income countries. Show less
