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Proc Natl Acad Sci U S A. 2015 Aug 4;112(31):9650-5. doi: 10.1073/pnas.1502651112. Epub 2015 Jul 20.

Reduced transmission of human schistosomiasis after restoration of a native river prawn that preys on the snail intermediate host.

Author information

1
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.
2
20|20 Initiative, Pasadena, CA 91105;
3
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;
4
US Geological Survey, Western Ecological Research Center, Marine Science Institute, University of California, Santa Barbara, CA 93106;
5
Department of Ecology, Evolution, and Marine Biology and Marine Science Institute, University of California, Santa Barbara, CA 93106;
6
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.
7
Espoir pour la Santé, Laboratoire de Recherches Biomédicales, BP 226 Saint-Louis, Senegal.
8
Department of Biology, Hopkins Marine Station, Stanford University, Pacific Grove, CA 93950;

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.

KEYWORDS:

control; disease; ecology; elimination; neglected tropical disease

PMID:
26195752
PMCID:
PMC4534245
DOI:
10.1073/pnas.1502651112
[Indexed for MEDLINE]
Free PMC Article

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