Vibrio parahaemolyticus

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Cholera’s seafaring cousins

V. parahaemolyticus is a marine Vibrio normally associated with food poisonings involving seafood consumption. It is a major cause of food poisoning in Asian countries. Outbreaks tend to be in coastal regions during the summer and autumn with higher water temperatures – it doesn’t like the cold. Most outbreaks involve undercooked squid, mackerel, tuna, sardines and shellfish such as oysters and clams. Certain strains (Kanagawa phenomenon-positive, KP+) are primarily involved with human disease.

Growth and Control Survival Inactivation (CCPs and Hurdles) Clinical Notes Reservoirs / Sources


Range 5-43°C, optimum 37°C. Growth is very rapid under optimum conditions.


Optimum 7.8-8.6. Range 4.8-11. Minimum pH for growth decreases as the incubation temperature increases towards the optimum. Growth was inhibited in the presence of 0.1% acetic acid (pH 5.1).


Can grow in the presence or absence of oxygen, but grows optimally under aerobic conditions.

Water Activity

Grows in NaCl concentrations from 0.5-10%. Optimum = 3%. aw range is 0.940 to 0.996, with an optimum of 0.980.

Survives freezing but numbers will be reduced 10-100 fold.


The organism dies at temperatures of 0-5°C. Cooking to an internal temperature of 65°C effectively inactivates this organism. D time at 65°C < 1 min, at 55oC 2.5 min. A low temperature pasteurisation of 10 minutes at 50°C has been suggested for oysters.


Thermal D time increases as pH increases from 5.0 to 8.0.

Water Activity

Very sensitive to drying. Fresh water inactivates the organism.


The organism is highly sensitive to 50 ppm butylated hydroxyanisole. It is inhibited by 0.1% sorbic acid.


D time of 15 seconds when exposed to chlorine or iodophor at 13 ppm.


A dose of 3 kGy has been recommended for the elimination of Vibrio from frozen shrimps. Quite sensitive to irradiation; D value of <0.1 kGy in fish at 24°C.


Not effective at removing Vibrio from shellfish.

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4-74 hours, mean 12-46 hours.


Abdominal cramps and watery diarrhoea. Sometimes nausea, vomiting and fever. Symptoms last from 1 to 7 days, occasionally longer. Mean duration 2.5 days. Hospitalisation is required in approximately 7% of cases. Usually self-limiting. Extraintestinal infections can occur.


Primarily gastrointestinal infection.


The KP+ factor is a haemolysin. Expression of this haemolysin seems to be responsible for the symptoms. However other virulence factors, such as a shiga-like toxin are also likely be involved.

At Risk Groups

No at risk groups reported for gastroenteritis.

Long Term Effects

Reactive arthritis has been reported.


Ingestion of 2 x 105 – 3 x 107 cells is required to cause disease in healthy adults, but it may be lower in the presence of antacids or food.


Gastroenteritis is usually self-limiting. Appropriate antibiotics may reduce symptoms.

Seafood is the food group most often associated with outbreaks.


Asymptomatic carriers are known to occur. Carriers act as a source of environmental contamination.


Occurs in marine animals including mammals, fish, shellfish, crustaceans and plankton.


Foods of marine origin may harbour this organism. Levels may approach 103/g in fresh seafood and may be greater in the warmer months, but are more typically present at around 10/g. Large proportions (60-100%) of seafood samples in the USA were found to contain the organism.


A normal inhabitant of the marine environment. The presence of the organism in the environment is heavily influenced by the season, occurring at the highest levels in the warmer months. However, typically > 99% of isolates from seawater are not of the human pathogenic kind.

Transmission Routes

Usually via seafood with careless temperature control.

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