Vibrio parahaemolyticus is a common marine bacterium found in tropical and warmer temperate seas. Consumption of seafood contaminated with V. parahaemolyticus can lead to acute gastro-enteritis. This is because a minority of strains produce thermostable directly or directly related haemolysins which are pathogenic in man. On average in the U.S. around 3,000 cases per year are recorded and in South East Asia, a pandemic serotype of V. parahaemolyticus (O3:K6) is responsible for around 40% of all seafood-associated illness.
Historically, in Europe, cases have been rare and usually related to travel to endemic regions or cross-contamination of seafood following harvest. However, recently several outbreaks have been reported in Europe associated with indigenously produced seafood. In 2004, O3:K6, V. parahaemolyticus-associated gastroenteritis was reported in Spain. Investigation of the outbreak implicated the consumption of edible crabs (Cancer pagurus) that had originated in the U.K. It was suggested, but not proven, that improper post harvest handling was the cause of contamination. Molecular characterisation of isolates collected from patients during this outbreak showed the emergence of the O3:K6 pandemic strain in Europe. Recently, this pandemic strain has been identified in the Northern Adriatric Sea indicating that it may be becoming established in European waters. It has been speculated that this increased incidence may be associated with warmer sea temperatures attributed to climate change.