NOROVIRUS, OYSTERS - UNITED STATES OF AMERICA: (LOUISIANA)

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A ProMED-mail post

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International Society for Infectious Diseases


Date: Sun 4 Apr 2010
Source: Times Picayune, New Orleans [edited]



Shutdown of Louisiana oyster grounds is largest in 10 years
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After at least 38 people became sick after eating raw oysters during
the past month [March 2010], Louisiana's seafood industry is
contending with the most widespread closures to state oyster grounds
in a decade.

A total of 3 harvest areas in St. Bernard, Plaquemines and parts of
Lafourche and Jefferson parishes have been closed to oyster fishing
as a precaution in the past 2 weeks. But the root of the stomach flu
outbreak remains a mystery to state health officials and those in the industry.

The disease, _Norovirus_ [infection], is a more common and much less
serious oyster-related sickness than the bacterial _Vibrio
vulnificus_ disease that prompted the Food and Drug Administration
(FDA) to flirt with restrictions on raw oysters last fall. But the
symptoms of norovirus [infection] -- fever, chills, aches, nausea,
and diarrhea that can last up to 2 days -- are not to be
underestimated. "It's certainly not a bad [!] virus, but it's one
that gets everybody's attention," said Jimmy Guidry, state health
officer with the Louisiana Department of Health and Hospitals (DHH).

As of last week, 38 cases of norovirus [infection] in Mississippi and
the New Orleans area were tied to oysters from the 3 separate zones
in Louisiana waters. A total of 11 people got sick near Pascagoula
after eating oysters at a seafood-related conference at the Grand Bay
National Estuarine Research Reserve; another 13 got sick at a wedding
in New Orleans. Although DHH has confirmed that everyone who was sick
had eaten oysters, Guidry said it's still unclear whether the problem
was due to contamination in the water where oysters were harvested or
if someone handling them passed on the virus.

Noroviruses are highly contagious, and can be transferred from
someone who has the virus onto the raw shellfish, or to another
person through human contact. That makes pinpointing the source of
the disease particularly challenging. DHH has tested the water in the
3 zones for fecal coliform, often present in sewage and human waste,
but found nothing. Sometimes the virus can get into the oysters if
boats dump waste overboard in a harvest area.

Unlike _Vibrio vulnificus_ bacteria, which can be reduced through
refrigeration or largely eliminated by post-harvest treatment
methods, noroviruses in oysters are difficult to track or prevent.

The Plaquemines beds will remain closed through Thursday [8 Apr 2010]
and the St. Bernard grounds through next week. The oyster grounds
near Grand Isle in Lafourche and Jefferson parishes are still under
investigation, because DHH officials believe the problem may be
confined to one specific harvest area. Industry officials say the
closures have not markedly affected the supply of oysters. There are
still vast areas of the state that remain open to fishing, and no new
cases have been reported in the past week.

Sherry Koptish, a manager at Felix's Restaurant and Oyster Bar in the
French Quarter, said a few people have asked about the virus but that
the bar has been full all week. John Tesvich, a co-owner of AmeriPure
Oysters in Franklin who chairs the state's oyster task force, said
the supply is still brisk but that the number of closures has been
unusual this year. "It happens annually in some areas of the country,
and unfortunately we've had more than our share this year," Tesvich
said. "We expect everything to be back to normal in the next couple
weeks. This is the way it's supposed to work. Industry would rather
stop harvesting if there's any indications of a problem with the
quality of the product."

What's most confounding is the geographic expanse of the closures, in
parts of the state that are not connected. Some believe the series of
extreme weather events this winter, with numerous fronts bringing
lots of rainfall during low tides, may have circulated more runoff
from the land into the water.

In the 1990s there was a series of norovirus closures in December
that hit the industry hard around Christmas and New Year's, a popular
time for the salty delicacy. Although it is later in the season,
industry observers say that any time news of illnesses breaks there
will be impacts on consumer attitudes. "Easter time is not the peak
for oyster consumption, but I wouldn't say it's the bottom of the
barrel, either," said Patrick Banks, who manages the state's oyster
program at the Louisiana Department of Wildlife and Fisheries.

[Byline: Chris Kirkham]

--
Communicated by:
ProMED-mail


[Norovirus infection associated with consumption of raw oysters is a
global problem (see ProMED-mail references below) and is more
frequently associated with sewage contamination of oyster beds than
with downstream processing of harvested oysters. There is no specific
treatment for norovirus-infection which results in transient illness
with no serious sequelae. The best protection is to avoid consumption
of uncooked oysters and related sea-food.

A map of the Louisiana oyster bats can be accessed at:
.
The HealthMap/ProMED-mail interactive map of the United States can be
used to locate Louisiana:
.
- Mod.CP]

[see also:
Norovirus, oysters - Europe: (UK, Norway, France, Sweden,
Denmark) 20100325.0954
2009
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Norovirus, raw oysters - USA: recall, alert 20091207.4169
2008
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Norovirus, oysters - New Zealand: (North Island) 20081013.3242
2007
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Norovirus, oysters - USA (TX): recall 20070304.0754
2006
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Norovirus, oysters - USA (OR) ex Korea 20061213.3503
Norovirus, oysters - New Zealand ex Korea 20060714.1947]
..................mhj/cp/ejp/mpp

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