Bad Bug Book:
Foodborne Pathogenic Microorganisms and Natural Toxins Handbook
Vibrio vulnificus, a lactose-fermenting, halophilic, gram-negative, opportunistic pathogen, is found in estuarine environments and associated with various marine species such as plankton, shellfish (oysters, clams, and crabs), and finfish. It is found in all of the coastal waters of the United States. [Cases of illness have also been associated with brackish lakes in New Mexico and Oklahoma.] Environmental factors responsible for controlling members of V. vulnificus in seafood and in the environment include temperature, pH, salinity, and increased dissolved organics.
This organism causes wound infections, gastroenteritis, or a syndrome known as "primary septicemia."
Wound infections result either from contaminating an open wound with sea water harboring the organism, or by lacerating part of the body on coral, fish, etc., followed by contamination with the organism. The ingestion of V. vulnificus by healthy individuals can result in gastroenteritis. The "primary septicemia" form of the disease follows consumption of raw seafood containing the organism by individuals with underlying chronic disease, particularly liver disease (see below). In these individuals, the microorganism enters the blood stream, resulting in septic shock, rapidly followed by death in many cases (about 50%). Over 70% of infected individuals have distinctive bulbous skin lesions.
Infective dose -- The infective dose for gastrointestinal symptoms in healthy individuals is unknown but for predisposed persons, septicemia can presumably occur with doses of less than 100 total organisms.
The culturing of the organism from wounds, diarrheic stools, or blood is diagnostic of this illness.
This organism has been isolated from oysters, clams, and crabs. Consumption of these products raw or recontaminated may result in illness.
No major outbreaks of illness have been attributed to this organism. Sporadic cases occur frequently, becoming more prevalent during the warmer months.
In a survey of cases of V. vulnificus infections in Florida from 1981 to 1987, Klontz et al. (Annals of Internal Medicine 109:318-23;1988) reported that 38 cases of primary septicemia (ingestion), 17 wound infections, and 7 cases gastroenteritis were associated with the organism. Mortality from infection varied from 55% for primary septicemia cases, to 24% with wound infections, to no deaths associated with gastroenteritis. Raw oyster consumption was a common feature of primary septicemia and gastroenteritis, and liver disease was a feature of primary septicemia.
In healthy individuals, gastroenteritis usually occurs within 16 hours of ingesting the organism. Ingestion of the organism by individuals with some type of chronic underlying disease [such as diabetes, cirrhosis, leukemia , lung carcinoma, acquired immune deficiency syndrome (AIDS), AIDS- related complex (ARC), or asthma requiring the use of steroids] may cause the "primary septicemia" form of illness. The mortality rate for individuals with this form of the disease is over 50%.
All individuals who consume foods contaminated with this organism are susceptible to gastroenteritis. Individuals with diabetes, cirrhosis, or leukemia, or those who take immunosuppressive drugs or steroids are particularly susceptible to primary septicemia. These individuals should be strongly advised not to consume raw or inadequately cooked seafood, as should AIDS / ARC patients.
Methods used to isolate this organism from foods are similar to those used with diarrheic stools. To date, all food isolates of this organism have been pathogenic in animal models.
FDA has a genetic probe for V. vulnificus; its target is a cytotoxin gene which appears not to correlate with the organism's virulence.
Sporadic cases continue to occur all year, increasing in frequency during the warmer months.
For more information on recent outbreaks see the Morbidity and Mortality Weekly Reports from CDC.
Literature references can be found at the links below.
Vibrio vulnificus FAQ's from the CDC.
What is Vibrio vulnificus? What sort of germ is it? How can an infection be diagnosed? How can the infections be treated?
Loci index for genome Vibrio vulnificus
Available from the GenBank Taxonomy database, which contains the names of all organisms that are represented in the genetic databases with at least one nucleotide or protein sequence.
More information for consumers of raw shellfish is available at this FDA brochure.