title: Introgression in Lake Malaŵi: increasing the threat of human urogenital schistosomiasis?
abstract: For the last 15 years, we have studied the relationships among cichlid snail-eating fishes, intermediate snail-host density, and the prevalence of human infection of Schistosoma haematobium in Lake Malaŵi and concluded that the increase of human infection is correlated with the decrease in snail-eating fishes in the shallow waters of the lake. We postulated that a strain of S. haematobium from other parts of Africa, which was introduced into the Cape Maclear region of Lake Malaŵi by tourists, was compatible with Bulinus nyassanus-which is a close relative of B. truncatus, and interbred with the indigenous strain of S. haematobium, which ultimately produced via introgression a strain that can use both B. globosus and B. nyassanus as intermediate hosts. This actively evolving situation involving intermediate snail-host switching and decline of Trematocranus placodon, a natural cichlid snail predator, will impact on transmission of urogenital schistosomiasis within the local communities and on tourists who visit Lake Malaŵi.
authors.affiliation: Department of Ecosytem Science and Management, The Pennsylvania State University, University Park, PA, 16802, USA, vc5@psu.edu.
authors.forename: Jay R
authors.initials: JR
authors.lastname: Stauffer
authors.forename: Henry
authors.initials: H
authors.lastname: Madsen
authors.forename: David
authors.initials: D
authors.lastname: Rollinson
mesh_terms: D000818:Animals; D023681:Cichlids; D049810:Genetic Speciation; D006790:Host-Parasite Interactions / Q000235:genetics*; D006801:Humans; D060106:Lakes / Q000469:parasitology; D008295:Malawi / Q000453:epidemiology; D015995:Prevalence; D012548:Schistosoma haematobium / Q000235:genetics* / Q000469:parasitology; D012553:Schistosomiasis haematobia / Q000453:epidemiology / Q000469:parasitology / Q000635:transmission*; D012908:Snails