> whether or not diseases could be transmitted by any American freshwater mollusks.

A few additional notes:

Eating freshwater or terrestrial mollusks raw would give high risk for
getting some unusual (at least for humans) parasites.  Also, there
could be bacteria or other microrganisms in or on the mollusks, plus
the issue of pollutants or other health hazards.  The latter relate to
the general water quality, though conceivably the mollusks could
accumulate the hazardous substance/organism in higher concentrations
than average in the water.

One of the major host species for human schistosomiasis, Biomphalaria
glabrata, is present in the southern U.S. and possibly at warm-water
settings elsewhere (e.g., near nuclear plant discharges).  Other
invasive or native species might possibly be able to host that or
other nasty diseases, but there is significant inter-population
variation in suceptibility (associated with cryptic speciation in some
cases).

Native and invasive freshwater species can be hosts of various
parasites that affect animals.  Potomac horse fever is a somewhat
complicated example-pleurocerids host flukes that host a virus that
causes the disease.  Swimmer's itch happens when schistosome larvae of
a species that can't live in humans mistakenly attack a human.  The
larvae bore into the skin and then die, creating an immune reaction.

> His response is below (with permission):
>
> No, you're not "showing your ignorance!"  That's such an interesting
> question, I'm going to answer it four times.
>
> 1) Nah, don't worry about it.  I've hand-collected freshwater mollusks all
> over North America for 40 years, and never given it a second thought.
>
> 2) Well, actually, some very widespread freshwater mollusk species can
> thrive in polluted environments.  I've seen strikingly high densities of
> Physa acuta, Lymnaea humilis, and Musculium transversum downstream from
> sewage treatment plants.  (Unionids, not so much!)  It might be a good idea
> to wash your hands after pulling anything from such waters - rocks, bottles,
> beer cans, snails or clams included.  There was a little scare in the Myrtle
> Beach area a summer ago when state wildlife officials advised residents of a
> trailer park not to handle Pomacea insularum introduced into a nasty
> drainage pond in their neighborhood.  See my blog post of 14Aug08 to read
> more:
> http://fwgna.blogspot.com/2008/08/two-dispatches-from-pomacea-front.html
>
> 3) Several years ago I visited Northern Michigan to sample Physa parkeri*
> from the lovely waters of Douglas Lake, at the University of Michigan
> Biological Station.  I made my collection in a one-gallon thermos jug,
> planning to transport the sample back to Charleston alive.   The next
> morning I was disappointed (but perhaps not terribly surprised) to discover
> that quite a few individuals had expired.  So I reached into the jug
> (repeatedly) to remove the dead individuals for preservation, leaving the
> live ones undisturbed.  See the case of schistosome dermatitis ("swimmers
> itch") that resulted:
> http://spinner.cofc.edu/~fwgna/images/swim-itch-rd.jpg
>
> 4) Nah, don't worry about it.  I never do.
>
> Cheers,
> Rob
>
>
> *Physa parkeri turned out to be an ecophenotypic variant of Physa gyrina.
> See Dillon & Wethington (2006) The Michigan Physidae revisited: A population
> genetic study.  Malacologia 48: 133-142.  PDF -
> http://dillonr.people.cofc.edu/Dillon_Wethington_2006_Malacologia.pdf
>
>
> ***************************************************
> Dr. Robert T. Dillon, Jr.
> Department of Biology, College of Charleston
> Charleston, SC 29424
>
>
> ________________________________



--
Dr. David Campbell
425 Scientific Collections
University of Alabama
"I think of my happy condition, surrounded by acres of clams"

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