Vibriosis in Shellfish
What is vibriosis?
Vibriosis is an intestinal disease caused by small bacteria called
vibrio, which are found in fish and shellfish dwelling in the sea or
rivers and streams where they meet the ocean. Although there are
several types of vibrio, V. parahaemolyticus and related species
are the most common in the northwest.
Where does it come from?
Vibrio occurs naturally in marine coastal waters. Because the
bacteria are more common in warmer months, 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 during
preparation or improper refrigeration of seafood can also lead to illness.
(See Food Safety Tips for safe food
handling practices.)
What are the symptoms of vibriosis?
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 it can
take as long as 4 days.
Who is at risk?
Anyone who eats raw or partially cooked fish or shellfish.
Because the bacteria multiply when it is warm, infection is more likely
during the warmer months of the year. Large numbers of bacteria are
needed to cause illness. People taking antacids are more likely to
get sick.
What is the treatment?
The disease usually runs its course in 2-3 days. A few cases
require hospitalization and/or antibiotic treatment. Replacement of
fluids through oral rehydration with glucose-saline or an IV is needed in
severe cases. Use of tetracycline can shorten the duration of
symptoms and excretion of organisms.
How can I prevent vibriosis?
Eat only well cooked shellfish, especially in summer months. Do
not rinse cooked food with seawater. Keep shellfish cold after
harvesting.
What other marine vibrio organisms exist?
Several other marine vibrios found in Washington cause intestinal
illness. The symptoms from these infections are similar to those from V.
parahaemolyticus. Other vibrio species, such as Vibrio
vulnificus, may cause more serious illnesses, however, these species
are not found in Washington but do occur elsewhere in the country.
What should I do if I suspect someone in my
family has vibriosis?
If severe diarrhea or fever persists, contact your primary care
provider.
For more information please call…
The Office of Shellfish and Water Protection (360)
236-3330, or Communicable Disease Epidemiology (206) 418-5500 (toll free
1-877-539-4344).
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