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Public Health Impact



Vibrio vulnificus infections typically occur as sporadic cases, not as outbreaks, which are defined as two or more cases. From 2007 - 2015, an average of 120 U.S. V. vulnificus infections per year (all modes of transmission) was reported to the Centers for Disease Control and Prevention (CDC).

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V. vulnificus case data obtained through the U.S. Centers for Disease Control and Prevention (CDC) via the Cholera and Other Vibrio Illness Surveillance System (COVIS)

In the bar graph above, cases are categorized into three groups according to mode of transmission:  1) confirmed and probable foodborne (seafood; on average, 23% of all cases); 2) confirmed and probable non-foodborne (52%); and 3) unknown transmission (25%). The prevalence of seafood consumed in these V. vulnificus cases was: oysters, 78% of cases; shrimp, 28%; fish, 18%; crab, 14%; clams, 12%; mussels, 6%; lobster, 7%; other shellfish, 7%; and crayfish, 1%.  (Percentages exceed 100 because many cases consumed more than one type of seafood during a meal or seven days prior to symptoms.)  Demographics of cases where molluscan shellfish (oysters, clams, mussels) was consumed were: median age, 59 (range 13-93), 86% male, 94% with pre-existing conditions, 93% hospitalized, and 43% died.  Non-foodborne transmission usually includes exposure of wounds to seawater, marine life, or raw seafood drippings.

Seasonality and Geographic Distribution of Cases


Because V. vulnificus bacteria flourish in warm seawater, infections show a seasonal trend with cases rising significantly in April, peaking in July, and decreasing in November. (refer to monthly bar graph below)

V. vulnificus case data obtained through the U.S. Centers for Disease Control and Prevention (CDC) via the Cholera and Other Vibrio Illness Surveillance System (COVIS)

Since warm Gulf of Mexico seawater provides optimum conditions for V. vulnificus growth, states bordering the Gulf usually report the most wound and shellfish consumption V. vulnificus cases. During the nine-year period ending December 31, 2015, Florida reported 252 cases, Texas reported 195, Louisiana, 107, Alabama, 49, and Mississippi, 38. (Cases include foodborne, non-foodborne, and unknown modes of transmission.)

Reported V. vulnificus Cases in the U.S. 2007 - 2015

In this period, the top five reporting states with the most cases were Florida (252), Texas (195), Louisiana (107), Maryland (81), and Virginia (57). Data:V. vulnificus case data obtained through the U.S. Centers for Disease Control and Prevention (CDC) via the Cholera and Other Vibrio Illness Surveillance System (COVIS)

Even though California does not border any Gulf coast states, raw Gulf oysters are popular with Hispanic consumers. Consequently, California reported 29 shellfish consumption V. vulnificus cases between 1998 and 2004. In an effort to reduce V. vulnificus cases, beginning in April 2003 California banned the sale of raw Gulf oysters from April through October, unless they are processed to reduce the level of V. vulnificus bacteria to non-detectable (post-harvest processed oysters). Some experts believe that numbers of V. vulnificus illnesses, as well as all food-borne illnesses, are under-reported and under-diagnosed. The CDC estimates that for every 1 foodborne V. vulnificus  case reported, another 1.87 cases occur (1).

Physician Reporting Requirements


It is imperative to report cases of V. vulnificus infection to local, territorial, and/or state health authorities so that incidence of illness can be tracked by the U.S. Food and Drug Administration and CDC and possible prevention strategies can be developed and/or evaluated. Since 2007, all U.S. states require doctors, hospitals, and/or labs to report confirmed and probable cases of V. vulnificus and other Vibrio infection to their state health agencies. (Refer to Council for State and Territorial Epidemiologists nationally notifiable conditions.)

Susceptibility and Mortality


Healthy people without chronic high-risk conditions are not at risk for consumption-related, serious V. vulnificus infection. If healthy people are infected from eating raw molluscan shellfish, their symptoms are usually mild and temporary (gastroenteritis); they rarely require hospitalization (2). However, healthy people are at risk for developing cellulitis from V. vulnificus infected wounds.

People with chronic high-risk conditions are susceptible to severe infection either by physical contact with V. vulnificus bacteria (through salt and brackish water, or live or raw seafood) and by consumption of raw molluscan shellfish (oysters, clams, mussels). These individuals are usually brought to hospital emergency rooms. The average mortality rate for shellfish consumption cases reported in the United States from 2007 - 2015 was 41%. However, in an analysis from an earlier time period that grouped shellfish-consumption cases according to pre-existing conditions, higher mortality rates were revealed for alcoholics (67%) and people with liver disease (61%). Liver disease was a pre-existing condition in 53% of the shellfish consumption cases (3).

Demographics of Shellfish Consumption Cases


Statistical analysis of molluscan shellfish consumption cases (2007 – 2015) revealed a median age of 59 (range of 13 - 93), 86% male, 94% with pre-existing conditions, 93% hospitalized, and 43% died.

The typical U.S. shellfish-consumption V. vulnificus case profile is a middle-aged, white man who is a heavy drinker and either is unaware of or ignores dietary risks. He consumes three to twelve raw oysters and develops septicemia (4).


  1. Scallan, E, Hoekstra RM, Angulo FJ, Tauxe RV, Widdowson MA, Roy SL, Jones JL, Griffin PM. Foodborne illness acquired in the United States – major pathogens. Emerg Infect Dis. 2011 Jan;17(1):1-15.

  2. Interstate Shellfish Sanitation Conference. 2003. Vibrio vulnificus Fact Sheet for Health Care Providers

  3. Bashin, M. 2004. Vibrio vulnificus Case Analysis 1993 - 2003 (unpublished report).  Interstate Shellfish Sanitation Conference.

  4. Tamplin, M., R. Hammond, P. Gulig, R. Baker. 2001. Vibrio vulnificus, a hidden risk in raw oysters (video).   A clinician's guide to V. vulnificus infection and treatment.

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Page last updated: November 12, 2017

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