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Scientists at the USGS Western Ecological Research Center study the many ecosystems of the Pacific Southwest. Follow our expeditions and projects through this outreach page, and learn more about your local landscape with our library of Outreach Factsheets and photos. Thanks for joining us!

Ben Young Landis
Outreach and Communications Coordinator

WERC Headquarters
3020 State University Drive East
Sacramento, CA 95819
Phone: (916) 278-9495
Fax: (916) 278-9475
Email: blandis@usgs.gov
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Macrobrachium vollenhovenii. Source: http://www.youtube.com/watch?v=wns_WhoD86w --Photographer: Courtesy of Project Crevette
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Ecological Science Helps Tackle Devastating Human Parasite
MONDAY APR 23 2012
Who you callin' a shrimp?

With the help of some ecologists, a species of freshwater prawn just might lend a big hand to combating one of the most devastating diseases in Africa.

Caused by a trematode parasite, schistosomiasis leads to internal organ and tissue damage in humans, sometimes inducing distinctive, distended abdomens in infected individuals. The disease is especially prevalent in Africa. 

The fun starts when the "cercariae" stage of these parasites burrow into a person's skin when a person wades into schisto-infested waters. As Elizabeth Huttinger of the non-profit Project Crevette explains in this YouTube video, "these larva move through the bloodstream to the lungs, and eventually turn into this green worm, living in mating pairs in the veins of the intestine and liver. There they produce up to 1,000 eggs a day..."

You get the picture. And it's not a pretty one for some 207 million infected people around the world.

Schistosomiasis symptoms. Source: http://www.youtube.com/watch?v=wns_WhoD86w --Photographer: Courtesy of Project Crevettes

Project Crevette has been testing the biocontrol of the Schistosoma parasite in Sénégal using a native prawn species, with the help of Susanne Sokolow, a postdoctoral researcher with the University of California, Santa Barbara, and USGS Western Ecological Research Center scientist Kevin Lafferty

Marine Ecologist Kevin Lafferty near Point Conception conducting field work.Lafferty, also a professor at UCSB and a parasite ecology specialist, has been advising the effort. He's been helping Sokolow to design a study testing the native prawn Macrobrachium vollenhovenii as a biocontrol agent for the parasite’s intermediate host -- snails.

This snail-eating prawn had previously been decimated due to a river dam project which altered the native ecosystem, allowing schisto-vector snails to thrive.

Schisto parasites rely on snails to complete their life cycle. So if snail populations could be kept down, then the prevalence of schisto in local waters and the risk of human infection just might be reduced. 

If Sokolow's experiments could show that prawns can effectively keep snail populations down -- and correlate that with a lower rate of schisto infections in the local community -- then Project Crevette could advocate for prawn-reintroduction programs in Sénégal watersheds.

On top of the vector-control benefit, local communities might even be able to turn the prawns into an aquaculture business and cultivate a new source of income.

Watch the full video from Project Crevette to learn more:

WERC embedded video should be here. You may not have a browser with enabled video embedding.

-- Ben Young Landis

All images captured from YouTube video produced by Project Crevette.

Lafferty photo credit: USGS.

Macrobrachium vollenhovenii eating snails, which can bear Schistosoma parasites. Source: http://www.youtube.com/watch?v=wns_WhoD86w --Photographer: Courtesy of Project Crevette

Macrobrachium vollenhovenii. Source: http://www.youtube.com/watch?v=wns_WhoD86w --Photographer: Courtesy of Project Crevette

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