| Vibriosis in Shellfish
What is vibriosis?
Vibriosis is an intestinal disease caused by small bacteria called vibrio.
Vibrio are found in fish and shellfish living in saltwater and in
rivers and streams where freshwater meets saltwater. Although there are
several types of vibrio, Vibrio parahaemolyticus [vib-ree-oh pair-uh-hee-moh-lit-uh-kuhs] and related species
are the most common in the northwest. |
Vibrio parahaemolyticus |
Where does vibrio come from?
Vibrio is found naturally in marine coastal waters, normally in low
numbers that pose no problems. It multiplies rapidly in warm
conditions, so fish and shellfish are more
likely to be contaminated in the summer.
How is it spread?
Most cases occur from eating raw or undercooked fish or shellfish. However, even fully cooked food can be recontaminated if rinsed with
seawater. Failure to keep shellfish cold after harvesting can
contribute to the growth of the bacteria. Poor food handling
practices during
preparation can also lead to illness.
(See Food Safety Tips for safe food
handling practices.)
Who is at risk?
Anyone who eats raw or partially cooked fish or shellfish can become
ill. People taking antacids are more likely to
get sick. Stomach acids help destroy bacteria, so when stomach acids are reduced, vibrio bacteria are more likely to pass
through the stomach and into the intestine, where the illness occurs.
What are the symptoms?
Symptoms include diarrhea, abdominal cramps, nausea, vomiting,
headache, fever, and chills. The illness is usually mild or moderate
and runs its course in 2-3 days. In severe cases, hospitalization
may be required.
How soon do symptoms appear?
Symptoms usually appear about 15 hours after consumption but can
take as long as four days.
What is the treatment for
vibriosis?
Treatment is not necessary in most cases. Drink plenty of liquids to
replace fluids lost through diarrhea. Severe cases may
require use of ciprofloxacin antibiotics and hospitalization.
What should I do if I
think I have vibriosis?
If severe diarrhea or fever persists, contact your primary care
provider. You should also report the illness to your
local health department, or you can email us
through our illness reporting address, sf.illness@doh.wa.gov.
What other marine vibrio organisms exist?
Several other marine vibrios found in Washington cause intestinal
illness, and symptoms from these infections are similar to those from
Vibrio parahaemolyticus. One type of vibrio, Vibrio
vulnificus, can cause serious illness and death, although there have
been no known illnesses attributed to Vibrio vulnificus in
Washington so far.
How can I prevent vibriosis?
Vibrio is destroyed by cooking shellfish to an internal temperature of 145°
F for 15
seconds.
- Eat only well-cooked shellfish, especially in summer months. Do
not consider shellfish to be fully cooked when the shells just open;
they need to cook longer to reach 145°
F.
- Don't rinse cooked food with seawater.
When harvesting:
- Just before you leave, check for closures due to vibrio,
biotoxins, and pollution at
www.doh.wa.gov/shellfishsafety.htm, by contacting your
local health department, or by
calling our biotoxin hotline at 1-800-562-5632.
- Harvest shellfish as soon as possible with the
receding tide.
- Don't harvest shellfish that have been exposed to the sun for more
than one hour, less in really hot weather.
- Keep shellfish cold after harvesting.
Are there any other illnesses associated with
shellfish?
Yes. There are two types of biotoxins
typically found in the northwest that you should be aware of: Domoic Acid
(ASP) and Paralytic Shellfish Poison (PSP
or "red tide"). Some people can
have an allergic reaction to shellfish.
Where can I get more information?
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