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

PNAS
By: , and 

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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.                            

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Reduced transmission of human schistosomiasis after restoration of a native river prawn that preys on the snail intermediate host
Series title PNAS
DOI 10.1073/pnas.1502651112
Volume 112
Issue 31
Year Published 2015
Language English
Publisher National Academy of Science
Contributing office(s) Western Ecological Research Center
Description 6 p.
First page 9650
Last page 9655
Country Guinea, Mali, Mauritania, Senegal
Online Only (Y/N) N
Additional Online Files (Y/N) N