title: Reduced transmission of human schistosomiasis after restoration of a native river prawn that preys on the snail intermediate host.
abstract: Eliminating human parasitic disease often requires interrupting complex transmission pathways. Even when drugs to treat people are available, disease control can be difficult if the parasite can persist in nonhuman hosts. Here, we show that restoration of a natural predator of a parasite's intermediate hosts may enhance drug-based schistosomiasis control. Our study site was the Senegal River Basin, where villagers suffered a massive outbreak and persistent epidemic after the 1986 completion of the Diama Dam. The dam blocked the annual migration of native river prawns (Macrobrachium vollenhoveni) that are voracious predators of the snail intermediate hosts for schistosomiasis. We tested schistosomiasis control by reintroduced river prawns in a before-after-control-impact field experiment that tracked parasitism in snails and people at two matched villages after prawns were stocked at one village's river access point. The abundance of infected snails was 80% lower at that village, presumably because prawn predation reduced the abundance and average life span of latently infected snails. As expected from a reduction in infected snails, human schistosomiasis prevalence was 18 ± 5% lower and egg burden was 50 ± 8% lower at the prawn-stocking village compared with the control village. In a mathematical model of the system, stocking prawns, coupled with infrequent mass drug treatment, eliminates schistosomiasis from high-transmission sites. We conclude that restoring river prawns could be a novel contribution to controlling, or eliminating, schistosomiasis.
authors.affiliation: Department of Biology, Hopkins Marine Station, Stanford University, Pacific Grove, CA 93950; Department of Ecology, Evolution, and Marine Biology and Marine Science Institute, University of California, Santa Barbara, CA 93106; shsokolow@gmail.com.
authors.forename: Susanne H
authors.initials: SH
authors.lastname: Sokolow
authors.affiliation: 20|20 Initiative, Pasadena, CA 91105;
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Huttinger
authors.affiliation: 20|20 Initiative, Pasadena, CA 91105;
authors.forename: Nicolas
authors.initials: N
authors.lastname: Jouanard
authors.affiliation: Department of Urology, School of Medicine, Stanford University, Stanford, CA 94304; Department of Research and Development, Biomedical Research Institute, Rockville, Maryland 20852; Division of Urology, Children's National Health System, Washington, DC 20010; Department of Urology, The George Washington University, Washington, DC 20037;
authors.forename: Michael H
authors.initials: MH
authors.lastname: Hsieh
authors.affiliation: US Geological Survey, Western Ecological Research Center, Marine Science Institute, University of California, Santa Barbara, CA 93106;
authors.forename: Kevin D
authors.initials: KD
authors.lastname: Lafferty
authors.affiliation: Department of Ecology, Evolution, and Marine Biology and Marine Science Institute, University of California, Santa Barbara, CA 93106;
authors.forename: Armand M
authors.initials: AM
authors.lastname: Kuris
authors.affiliation: Centre d'Infection et d'Immunité de Lille, Institut Pasteur de Lille, 59019 Lille, France; Espoir pour la Santé, Laboratoire de Recherches Biomédicales, BP 226 Saint-Louis, Senegal.
authors.forename: Gilles
authors.initials: G
authors.lastname: Riveau
authors.affiliation: Espoir pour la Santé, Laboratoire de Recherches Biomédicales, BP 226 Saint-Louis, Senegal.
authors.forename: Simon
authors.initials: S
authors.lastname: Senghor
authors.affiliation: 20|20 Initiative, Pasadena, CA 91105;
authors.forename: Cheikh
authors.initials: C
authors.lastname: Thiam
authors.affiliation: 20|20 Initiative, Pasadena, CA 91105;
authors.forename: Alassane
authors.initials: A
authors.lastname: N'Diaye
authors.affiliation: 20|20 Initiative, Pasadena, CA 91105;
authors.forename: Djibril Sarr
authors.initials: DS
authors.lastname: Faye
authors.affiliation: Department of Biology, Hopkins Marine Station, Stanford University, Pacific Grove, CA 93950;
authors.forename: Giulio A
authors.initials: GA
authors.lastname: De Leo
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D001700:Biomphalaria / Q000469:parasitology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006790:Host-Parasite Interactions; D006801:Humans; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D033541:Palaemonidae / Q000502:physiology*; D011235:Predatory Behavior; D015995:Prevalence; D045483:Rivers; D012547:Schistosoma / Q000502:physiology; D012552:Schistosomiasis / Q000453:epidemiology / Q000469:parasitology* / Q000635:transmission*; D055815:Young Adult
keywords: control; disease; ecology; elimination; neglected tropical disease