Eric S. Loker: Research

Biology of the Snails That Transmit
Human Schistosomiasis,
Including Ways to Control Schistosomes in Snails

Schistosomiasis infects more than 230 million people worldwide and has proven difficult to control with chemotherapy alone. Increasingly, it has been recognized that it would be beneficial to complement the treatment of people with ways to control larval schistosome parasites as they occur in their snail hosts.

We are engaged in a program to explore the potential of indigenous trematodes to compete with and displace schistosome sporocysts in infected snails, thereby reducing the number of infective cercariae produced and available to infect people.

We are also attempting to identify new means to control snails, including identifying snail viruses and other potential pathogens like nematodes, and snail predators like indigenous crustaceans. Our basic snail studies include use of RNA-seq to characterize the responses of snails to schistosome infection as well as stressors like molluscicidal chemicals.

Lake Victoria

A typical scene along the shore of Lake Victoria, where Schistosoma mansoni cercariae that are shed into the water from freshwater snails like Biomphalaria sudanica penetrate human skin and eventually develop into adult worms responsible for causing schistosomiasis. Many other species of trematodes, such as those infecting the birds seen in the background, also infect B. sudanica snails in their larval stages and can compete with and prey upon schistosome larvae. Diverse assemblages of trematodes supported by a wealth of different vertebrate species living in or near the lake can interfere with the transmission of this human disease.