Hazard identification is the identification of biological, chemical, or physical agents capable of causing adverse health effects that may be present in a particular food or group of foods. V. parahaemolyticus is a Gram-negative, halophilic bacterium that occurs naturally in estuaries and is recognized as an important bacterial seafood-borne pathogen throughout the world. The organism can cause an acute gastroenteritis and, on rare occasions, septicemia. The minimum infectious dose is not known. It is normally present in many seafoods, including fish, crustaceans, and molluscan shellfish. However, not all strains of V. parahaemolyticus cause illness and, in fact, pathogenic strains very rarely have been isolated from the environment or seafood. Apparently non-pathogenic V. parahaemolyticus are far more prevalent in nature. Several different virulence traits have been associated with the pathogenesis of V. parahaemolyticus strains. These include their ability to: a) produce a thermostable direct hemolysin (TDH) (96), b) to invade the enterocytes (3) and c) to produce an enterotoxin (61). However, these last two characteristics are not normally investigated in the environmental or clinical isolates, and the only trait known to reliably distinguish pathogenic from non-pathogenic V. parahaemolyticus is the production of a thermostable direct hemolysin (TDH). Pathogenic strains possess a tdh gene and produce TDH, and non-pathogenic strains lack the gene and the trait (96). Non-pathogenic strains, as identified by the absence of the TDH, are predominantly found in the environment.
The most common clinical manifestation of V. parahaemolyticus is gastroenteritis, which is usually a self-limited illness with moderate severity and short duration (11, 12, 57). However, on rare occasions, infection can result in septicemia that can be life threatening (57, 83). Gastroenteritis, due to a specific organism, is an inflammation of the gastrointestinal tract, characterized by diarrhea, vomiting, or abdominal cramps, and that organism is isolated from a stool sample. Septicemia is a systemic disease, characterized by fever or hypotension, and the organism is isolated from the blood. Patients with septicemia often have underlying medical conditions (83).
Hypertext updated by bap/kwg/dms 2001-JAN-30