Authors

Discussion

Schistosomiasis is a major socio-economic and public-health problem in many sub-Saharan African countries. After large mass drug administration (MDA) campaigns, prevalence of infection rapidly returns to pre-treatment levels. The traditional egg based diagnostic for schistosome infections, Kato-Katz, is being substituted in many settings by circulating antigen recognition based diagnostics, such as the point-of-care circulating cathodic antigen test (POCCCA). The relationship between these two diagnostics, particularly after treatment in drug-efficacy studies, is poorly understood. We created an inference model of schistosome infections to better understand and quantify the relationship between these two egg and adult worm antigen based diagnostics. Due to the semi-quantitative nature of CCA, we focused on the current major challenges of interpreting “trace” CCA results. Our analyses suggest that CCA is generally a better predictor of prevalence, particularly after treatment, and that trace CCA results are typically associated with truly infected individuals. Even though prevalence rises to pre-treatment levels only a few months after MDAs, our model suggests that the average infection level is much lower, and is probably due to a smaller burden of surviving juveniles from when the treatment occurred. This work helps to better understand CCA diagnostics and the interpretation of post-treatment prevalence estimations.