Vibrio parahaemolyticus infection - including symptoms, treatment and prevention

Vibrio parahaemolyticus is a bacterium found in marine, coastal and tidal waters, and most commonly causes gastroenteritis (gastro).

Vibrio parahaemolyticus infection is a notifiable condition1

How Vibrio parahaemolyticus is spread

Vibrio parahaemolyticus infection can be acquired by eating raw or undercooked shellfish or drinking contaminated water. Eating raw oysters is the most common way the infection is spread as the organism naturally lives in the warm tidal waters where oysters grow. Eating raw or undercooked fish and crustaceans, such as crabs and lobsters, has also been associated with food-borne outbreaks of this infection.

Less commonly, the organism causes wound infections when seawater contaminates open wounds.

V. parahaemolyticus does not usually spread from person to person, however, person-to-person spread is possible if there is poor personal hygiene.

Signs and symptoms of Vibrio parahaemolyticus infection

Vibrio parahaemolyticus infection causes symptoms of gastro including:

  • watery diarrhoea (occasionally bloody diarrhoea)
  • abdominal cramps
  • nausea
  • vomiting
  • fever
  • headache.

Symptoms usually occur within 24 hours of eating the contaminated food.

Usually symptoms are mild to moderate in severity and lasts around 3 days (range from 8 hours to 12 days). However, the infection can be severe in people with immunosuppression, such as people receiving cancer treatment.

Where V. parahaemolyticus infects a wound, symptoms around the wound may include:

  • pain
  • redness
  • warmth
  • pus or discharge.

Diagnosis of Vibrio parahaemolyticus infection

Diagnosis is made by testing of faeces, wound swab or other clinical specimens.

Incubation period

(time between becoming infected and developing symptoms)

Usually around 24 hours but can be between 4 to 96 hours.

Infectious period

(time during which an infected person can infect others)

V. parahaemolyticus does not usually spread from person to person.

Treatment for Vibrio parahaemolyticus infection

Antibiotic treatment is not usually needed for V. parahaemolytiticus gastro, however, in cases with prolonged diarrhoea, antibiotic therapy may be needed.

The following are general recommendations for the treatment of gastro:

  • Give plenty of fluids. Oral rehydration solution is highly recommended for children and adults with mild to moderate dehydration. It is available at pharmacies and should be administered following the instructions on the packaging.
  • Give mildly unwell children their usual fluids more often; however avoid carbonated (fizzy) drinks or undiluted juice.
  • Do not give medicines to prevent vomiting or diarrhoea (especially in children), except where specifically advised by a doctor.
  • Continue to breastfeed babies throughout their illness.
  • Children on formula or solid diets should restart their normal diet (including full strength lactose containing milk) following rehydration with oral rehydration solution.
  • Give children who are hungry their usual foods, but avoid foods high in sugar or fat.

Seek medical advice if wound infection is suspected. Wound infections should be treated with antibiotics. Also seek medical advice if any of the following symptoms develop:

Adults

  • signs of dehydration, such as being thirsty, decreased urination, lethargy, dry mouth, feeling faint on standing
  • fever
  • severe abdominal pain
  • bloody diarrhoea.

Children

  • signs of dehydration, such as thirst and decreased urination, lethargy, dry mouth, sunken eyes, feeling faint on standing
  • fever
  • abdominal pain
  • bloody diarrhoea
  • any symptoms in a child less than 12 months of age.

Prevention of Vibrio parahaemolyticus infection

Infections with V. parahaemolyticus can be prevented by the following measures:

  • Exclude people with Vibrio parahaemolyticus infection from childcare, preschool, school and work until there has been no diarrhoea for at least 24 hours. If working as a food handler in a food business, the exclusion period should be until there has been no diarrhoea or vomiting for 48 hours. People with Vibrio parahaemolyticus wound infections do not require exclusion.
  • Avoid consumption of raw or undercooked seafood such as oysters, especially during warm summer periods or if at increased risk of severe diseases (such as people with immune suppression).
  • Keep raw seafood separated from ready to eat foods when preparing or storing food.
  • Wash hands with soap and clean water before and after handling raw seafood.
  • Wash hands after going to the toilet, after changing a nappy and after handling rubbish.
  • Avoid using seawater for cooking.
  • Avoid exposing open wounds to seawater. If wounds are exposed then wash with soap and clean water.

Useful links

1 – In South Australia the law requires doctors and laboratories to report some infections or diseases to SA Health. These infections or diseases are commonly referred to as 'notifiable conditions'.