Preliminary investigation into xenomonitoring as a tool for monitoring and evaluation of schistosomiasis community-wide mass drug administration campaign: prospects and limitations

Schistosomiasis continues to afflict over 200 million people, exerting health and economic losses to endemic countries, the majority of which are in sub-Saharan Africa. Despite decades of preventive chemotherapy, the disease persists and is widespread in Ghana. The current strategy of monitoring and evaluating mass drug administration is laborious, expensive, and bureaucratic. In this study, we leverage a communitywide mass drug administration project in schistosomiasis endemic communities to investigate the potential of xenomonitoring for evaluating mass drug administration campaigns in Ghana. Freshwater snails were collected at six different timepoints from human-water contact points of three schistosomiasis endemic communities along the Weija Lake in Ghana. Snails were identified by shell morphology and subsequently stimulated to shed cercariae. Shed cercariae were identified morphologically and molecularly by PCR and gel electrophoresis verification of amplicons to confirm Schistosoma species infection. The prevalence of Schistosoma infection in snail hosts was determined for each snail collection timepoint. The chi-square test of independence and logistic regression analysis were used to determine statistical significance at p  < 0.05 and a confidence interval of 95% using SPSS. A total of 2201 snails consisting of 74.7% Bulinus spp. and 25.3% Biomphalaria spp. were collected across all timepoints. The prevalence of human-specific Schistosoma spp ( Schistosoma mansoni and Schistosoma haematobium ) in snails declined significantly to 0.6% two months post-first MDA and 0.4% 6 months post-second mass drug administration compared to baseline prevalence of 2.8%. The logistic regression showed substantially lower odds of snails getting infected at 2 months post-first MDA and 6 months post-second MDA. This study presents preliminary insight into the potential of snail xenomonitoring as a tool for monitoring and evaluating communitywide praziquantel MDA in schistosomiasis endemic communities. However, several methodological lapses need fixing and validation with parallel evaluation from human clinical samples.