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Vibrio species are bacteria that occur naturally in marine waters. Eating undercooked or raw shellfish, especially raw oysters, is the main risk for acquiring vibriosis from infection with Vibrio parahaemolyticus. Growth of Vibrio species in seawater is amplified during the warm months and Vibrio levels in shellfish increase during the summer.

Unlike infections with V. parahaemolyticus, which cause symptoms like watery diarrhea, abdominal cramping, nausea, and vomiting, V. alginolyticus infections typically present as skin or inner ear infections. Whereas raw oysters and shellfish tend to be the predominant exposure for V. parahaemolyticus cases, V. alginolyticus cases are more often associated with recreational water exposure such as swimming or scuba diving; cases of V. alginolyticus often have a pre-existing open wound (such as an ear infection or cut on the foot) that becomes infected when exposed to water containing the bacteria.

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Vibriosis in King County

Purpose of surveillance:

  • To identify common source outbreaks
  • To identify and eliminate sources of transmission including contaminated food and water
  • To target educational messages about how to reduce the risk of infection to persons at high risk

Vibriosis case data

Local epidemiology for vibriosis cases reported during 2016:

  • Thirty-two cases of vibriosis were reported in 2016, compared to a five-year average of 33 cases per year. Beginning in 2016, cases began being detected by DNA-based gastrointestinal syndrome panels (PCR). The availability of such panels might result in increased testing by health care providers and improved detection of pathogens including Vibrio bacteria.
  • One case was hospitalized, and none died.
  • Twenty-three cases (72%) were infected with Vibrio parahaemolyticus; other reported strains included V. alginolyticus (2), V. fluvialis (1), V. vulnificus (1), and non-toxigenic V. cholerae (1). Subtyping was not available for four cases.
  • Three cases, including the person with non-toxigenic V. cholerae, likely acquired their infections while traveling internationally. Both persons with V. alginolyticus had wound infections that were contaminated during local recreational water exposure. The person infected with V. vulnificus was most likely exposed to the bacteria through a wound that was sustained while fileting farmed tilapia fish in preparation for consumption. The majority of the remaining cases acquired their infections from consuming raw oysters, commercially sourced in and outside of Washington state. Unlike other years, no cases in 2016 were linked to the recreational harvest of shellfish. The source of infection could not be identified for six cases.
  • Over the last ten years in Washington state, 20–95 cases have been reported, with the number varying depending on environmental conditions.

Link/share our site at www.kingcounty.gov/vibrio