Spread and characteristics of Vibrio parahaemolyticus in Lishui, Zhejiang, 2014–2018

ObjectiveTo investigate the spread, serotype, virulence gene and molecular typing characteristics of Vibrio parahaemolyticus in Lishui of Zhejiang province and provide evidence for the prevention of foodborne diseases.

MethodsA total of 11420 stool samples of clinical diarrhea patients in foodborne disease surveillance and 497 food samples in food safety risk surveillance were collected in Lishui from 2014 to 2018 for the isolation and culture of V. parahaemolyticus, and the distribution characteristics of positive strains were analyzed. Serological typing, virulence gene detection and pulsed field gel electrophoresis (PFGE) for molecular typing were performed for the strains.

ResultsA total of 296 strains of V. parahaemolyticus were isolated, in which 251 were from diarrhea patients and 45 were from foods. V. parahaemolyticus was mainly detected during July-September, The cases were mainly adults and most of them usually dined at home. O3∶K6 was the main serotype and tdh⁺trh^-tlh⁺ was the virulence genotype detected in patients. O2 was the main serotype and tdh^-trh^-tlh⁺ was the virulence genotype detected in foods. Forty eight strains of V. parahaemolyticus could be classified into 42 PFGE banding patterns, and the banding pattern similarity values were from 6.16% to 100.00%.

ConclusionIt is necessary to strengthen the health supervision for V. parahaemolyticus infection and health education about having a good dining habit and improving the household cooking process of aquatic products during July-September. The genetic similarity of the V. parahaemolyticus strains spreading in Lishui was low and polyclonal sources might exist. Serotype O3∶K6 was mainly detected in patients, and O2 was mainly in foods.