Jennifer D. Castleman

Herein, we summarize what we consider are major contributions resulting from the Schistosomiasis Consortium for Operational Research and Evaluation (SCORE) program, including its key findings and key messages from those findings. Briefly, SCORE’s key findings are as follows: i) biennial mass drug administration (MDA) with praziquantel can control schistosomiasis to moderate levels of prevalence; ii) MDA alone will not achieve elimination; iii) to attain and sustain control throughout endemic areas, persistent hotspots need to be identified following a minimal number of years of annual MDA and controlled through adaptive strategies; iv) annual MDA is more effective than biennial MDA in high-prevalence areas; v) the current World Health Organization thresholds for decision-making based on the prevalence of heavy infections should be redefined; and vi) point-of-care circulating cathodic antigen urine assays are useful for Schistosoma mansoni mapping in low-to-moderate prevalence areas. The data and specimens collected and curated through SCORE efforts will continue to be critical resource for future research. Besides providing useful information for program managers and revision of guidelines for schistosomiasis control and elimination, SCORE research and outcomes have identified additional questions that need to be answered as the schistosomiasis community continues to implement effective, evidence-based programs. An overarching contribution of SCORE has been increased cohesiveness within the schistosomiasis field-oriented community, thereby fostering new and productive collaborations. Based on SCORE’s findings and experiences, we propose new approaches, thresholds, targets, and goals for control and elimination of schistosomiasis, and recommend research and evaluation activities to achieve these targets and goals.

For the past 10 years, the Schistosomiasis Consortium for Operational Research and Evaluation (SCORE), funded by the Bill & Melinda Gates Foundation, has been supporting operational research to provide a stronger evidence base for controlling and moving toward elimination of schistosomiasis. The SCORE portfolio was developed and implemented with engagement from many stakeholders and sectors. Particular efforts were made to include endemic country neglected tropical disease program managers. Examples of the challenges we encountered include the need to balance rigor (e.g., conducting large cluster-randomized trials) with ensuring relevance to real-world settings, allowing for local contexts while standardizing key study aspects, adjusting to evolving technologies, and incorporating changing technologies into multiyear studies. The Schistosomiasis Consortium for Operational Research and Evaluation's findings and data and the collected specimens will continue to be useful in the years to come. Our experiences and lessons learned can benefit both program managers and researchers conducting similar work in the future.

Schistosomiasis control programs rely heavily on mass drug administration (MDA) campaigns with praziquantel for preventative chemotherapy. Areas where the prevalence and/or intensity of schistosomiasis infection remains high even after several rounds of treatment, termed “persistent hotspots” (PHSs), have been identified in trials of MDA effectiveness conducted by the Schistosomiasis Consortium for Operational Research and Evaluation (SCORE) in Kenya, Mozambique, Tanzania, and Côte d’Ivoire. In this analysis, we apply a previously developed set of criteria to classify the PHS status of 531 study villages from five SCORE trials. We then fit logistic regression models to data from SCORE and publically available georeferenced datasets to evaluate the influence of local environmental and population features, pre-intervention infection burden, and treatment scheduling on PHS status in each trial. The frequency of PHS in individual trials ranged from 35.3% to 71.6% in study villages. Significant relationships between PHS status and MDA frequency, distance to freshwater, rainfall, baseline schistosomiasis burden, elevation, land cover type, and village remoteness were each observed in at least one trial, although the strength and direction of these relationships was not always consistent among study sites. These findings suggest that PHSs are driven in part by environmental conditions that modify the risk and frequency of reinfection.

The relationship between results from Kato-Katz (KK) fecal microscopy and urine-based point-of-care circulating cathodic antigen (POC-CCA) assays for Schistosoma mansoni infection remains a critical issue. This systematic literature review of 25 published papers compares prevalence of S. mansoni infection by KK with that by the POC-CCA assay. Nineteen published studies met our inclusion criteria for data extraction and analysis. Above a prevalence of 50% by KK, KK and POC-CCA results yielded essentially the same prevalence. Below 50% prevalence by KK, the prevalence by the POC-CCA assay was between 1.5- and 6-fold higher and increased as prevalence by KK decreased. Five of nine publications met inclusion criteria for extractable data on intensity of S. mansoni infection by KK assay and visual band density using the POC-CCA assay. A clear positive relationship exists between intensity by the KK and POC-CCA assays. This systematic review indicates that below 50% prevalence, the POC-CCA assay is much more sensitive than the KK assay. However, the existing data are inadequate to precisely define the relationship between POC-CCA and KK at lower levels of KK prevalence. More studies directly comparing the two assays in low-prevalence areas are essential to inform decision-making by national schistosomiasis control programs.