***Note: As of September 7, seven people in the area affected by Hurricane Katrina have been reported to be ill from the bacterial disease, Vibrio vulnificus. Four have died.
is a bacterium in the same family as
those that cause cholera. It normally lives in warm seawater and is
part of a group of vibrios that are called "halophilic" because
they require salt.
can cause disease in those who eat
contaminated seafood or have an open wound that is exposed to
seawater. Among healthy people, ingestion of
can cause vomiting, diarrhea, and abdominal pain.
In immunocompromised persons, particularly those with chronic
can infect the bloodstream,
causing a severe and life-threatening illness characterized by
fever and chills, decreased blood pressure (septic shock), and
blistering skin lesions.
infections are fatal about 50% of the time.
can also cause an infection of the skin
when open wounds are exposed to warm seawater. These infections may
lead to skin breakdown and ulceration. Persons who are
immunocompromised are at higher risk for invasion of the organism
into the bloodstream and potentially fatal complications.
is a rare cause of disease, but it is also
underreported. Between 1988 and 1995, CDC received reports of over
infections from the Gulf Coast states,
where the majority of cases occur. There is no national
surveillance system for
, but CDC collaborates
with the states of Alabama, Florida, Louisiana, Texas, and
Mississippi to monitor the number of cases of
infection in the Gulf Coast region.
Persons who are immunocompromised, especially those with chronic
liver disease, are at risk for
when they eat
raw seafood, particularly oysters. A recent study showed that
people with these preexisting medical conditions were 80 times more
likely to develop
bloodstream infections than
were healthy people. The bacterium is frequently isolated from
oysters and other shellfish in warm coastal waters during the
summer months. Since it is naturally found in warm marine waters,
people with open wounds can be exposed to
through direct contact with seawater. There is no evidence for
person-to-person transmission of
infection is diagnosed by routine stool,
wound, or blood cultures. The laboratory should be notified when
this infection is suspected by the physician, since a special
growth medium can be used to increase the diagnostic yield. Doctors
should have a high suspicion for this organism when patients
present with gastrointestinal illness, fever, or shock following
the ingestion of raw seafood, especially oysters, or with a wound
infection after exposure to seawater.
infection is treated with antibiotics.
Doxycycline or a third-generation cephalosporin (e.g., ceftazidime)
infection is an acute illness, and those
who recover should not expect any long-term consequences.
Although oysters can be harvested legally only from waters free
from fecal contamination, even legally harvested oysters can be
because the bacterium is
naturally present in marine environments.
not alter the appearance, taste, or odor of oysters.
Timely, voluntary reporting of
to CDC and to regional offices of the Food and Drug Administration
(FDA) will help collaborative efforts to improve investigation of
these infections. Ongoing research may help us to predict
environmental or other factors that increase the chance that
oysters carry pathogens.
Some tips for preventing
particularly among immunocompromised patients, including those with
underlying liver disease:
- Do not eat raw oysters or other raw shellfish.
Cook shellfish (oysters, clams, mussels) thoroughly:
- For shellfish in the shell, either a) boil until the shells
open and continue boiling for 5 more minutes, or b) steam until the
shells open and then continue cooking for 9 more minutes. Do not
eat those shellfish that do not open during cooking.
- Boil shucked oysters at least 3 minutes, or fry them in oil at
least 10 minutes at 375°F.
- Avoid cross-contamination of cooked seafood and other foods
with raw seafood and juices from raw seafood.
- Eat shellfish promptly after cooking and refrigerate
- Avoid exposure of open wounds or broken skin to warm salt or
brackish water, or to raw shellfish harvested from such
- Wear protective clothing (e.g., gloves) when handling raw