Schistosomiasis, snails and prawns: The interplay of parasitology and ecology

Discussion

Schistosomiasis is a parasitic disease that affects more than 250 million people, mainly in sub-Saharan Africa. Transmission occurs where people contact open freshwater bodies that are inhabited by specific intermediate host snails. The current mainstay of control is preventive chemotherapy that is the periodic administration of single-dose praziquantel to school-aged children and other high-risk groups in areas where schistosomiasis is endemic. However, this strategy fails to protect people from rapid reinfection. Hence, additional control measures are warranted whenever human and financial resources allow. Historically, snail control has been a key feature of successful schistosomiasis control programmes. Recent studies in Senegal suggest that specific species of prawns act as natural predators of snails, and hence, might control human schistosomiasis. With financial support from the Schistosomiasis Consortium for Operational Research and Evaluation (SCORE), we have conducted a study in two hydrological systems in Côte d’Ivoire. Our aim was to explore the association between the presence and density of intermediate host snails of schistosomiasis (Bulinus and Biomphalaria), freshwater prawns (Macrobrachium) and the prevalence of schistosomiasis in children and adults. The design of this study, field and laboratory methods and preliminary results will be presented. Identified research needs will be highlighted.