Short-term Evaluation of Mass Drug Administration of Praziquantel Reveals contrasting Prevalences by Microscopy and Immunological Assay in Ghana

Resumo

Schistosomiasis caused by Schistosoma species remains a significant public health issue, particularly in sub-Saharan Africa. In Ghana, Schistosoma haematobium and Schistosoma mansoni are prevalent, necessitating interventions like mass drug administration (MDA) of praziquantel (PZQ). This study assesses the impact of mass drug administration (MDA) of praziquantel (PZQ) on the prevalence and immunological responses in a schistosomiasis-endemic community in Ghana. A longitudinal study involving 112 participants was conducted in Vea area located near the Vea irrigation dam in the Bongo District of the Upper-East Region of Ghana. The main occupation of the people is farming and a few fishing activities. These pre- and post-treatment assessments included microscopy to detect Schistosoma eggs in urine and stool. Enzyme-linked immunosorbent assay (ELISA) was used to evaluate anti-Schistosoma IgM, IgG, IgG4, and IgE antibodies using S. haematobium soluble egg antigen (ShSEA), S. haematobium adult worm antigen (ShAWA), S. mansoni soluble egg antigen (SmSEA), and S. mansoni adult worm antigen (SmAWA).Microscopy diagnosis revealed a significant reduction in the overall prevalence of schistosomiasis, dropping from 35.7% (CI: 27% - 45%) pre-treatment to 4.5% (CI: 2% - 10%) post-treatment an 88% reduction. In contrast, levels of ELISA-detected anti-Schistosoma spp IgM and IgG to SEA were persistently high, with overall prevalence increasing from 79.5% (CI: 70% - 85%) pre-treatment to 90.2% (CI: 83% - 94%) post-treatment. The pre-treatment average infection intensities for Sh and Sm decreased from 112 eggs/10 ml of urine and 91eggs/g of stool to 12 eggs/10 ml of urine and 24 eggs/g of stool respectively. The average egg reduction rates (ERR) were 89.6% and 73.7% for Sh and Sm respectively. IgG4 levels decreased significantly post-treatment for anti-SmSEA but increased significantly for anti-ShSEA, reflecting differences in chronic antigen exposure. IgE levels increased significantly across anti-ShSEA, anti-ShAWA, anti-SmSEA, and anti-SMAWA post-treatment, highlighting heightened immune response to Schistosoma spp. antigens released during parasite destruction. These findings support the critical role of MDA programs in schistosomiasis control however, the contrasting prevalence results by the two diagnostic tests suggest the need for improved diagnostic tests for the assessment of schistosomiasis MDA campaigns in endemic communities. Indicators such as ERR and infection intensities and immunological parameters such as population-level IgE and IgG4 must be factored into the overall evaluation of MDA campaigns.