Vibrio parahaemolyticus

Vibrio parahaemolyticus



NAME: Vibrio parahaemolyticus


CHARACTERISTICS: Vibrio parahaemolyticus , of the Vibriomaceae family, is a gram- negative, halophilic, non-sporeforming, curved rod-shaped bacterium that is 0.5 – 0.8 μm in width and 1.4 – 2.4 μm in length(1,2,3). It is an oxidase-positive facultative anaerobe that can ferment glucose without gas production(4). It has a polar flagellum which enables its high motility in liquid media, and its lateral flagella allow it to migrate across semi-solid surfaces by swarming(2). Virulent strains isolated from patients have been shown to produce thermostable direct hemolysin (TDH), and/or TDH-related hemolysin, which is a characteristic that is not observed in other non-pathogenic/non-virulent strains found in the environment. TDH-producing isolates are known as Kanagawa positive and can be identified using β-hemolysis on a Wagatsuma blood agar.


PATHOGENICITY/TOXICITY: Infections usually present in one of three major clinical syndromes: 60-80% of infections cause gastroenteritis, 34% wound infections, and 5% septicaemia(4). The most common presentation is gastroenteritis, with symptoms including diarrhea (sometimes bloody and watery) with abdominal cramps, nausea, vomiting, headache, chills, and low-grade fever(1). Infection is usually self-limiting and of moderate severity, lasting approximately 3 days in immunocompetent patients, and can be treated with oral rehydration alone(2). Wound infection and septicaemia can also results from exposure to the bacteria, and was the cause of 3 cases and 2 deaths in Louisiana and Mississippi after Hurricane Katrina in 2005(5). Fatal cases of septicaemia may occur in immunocompromised patients or those with a pre-existing medical condition (such as liver disease, cancer, heart disease, recent gastric surgery, antacid use, or diabetes).

EPIDEMIOLOGY: Worldwide – widely distributed in inshore marine waters, and has been found in seawater, sediments, and is a part of the natural flora of bivalve shellfish(2). The bacteria are most prevalent during warm summer seasons. Food-borne outbreaks have been caused by V. parahaemolyticus (serotype O3:K6 strain has increasing prominence) in Chile, France, Japan, Korea, Laos, Mozambique, Peru, Russia, Spain, Taiwan, United States, and especially in far east countries such as India, Bangladesh, and Thailand, where raw seafood consumption is high(1,2). The first recorded outbreak was in Japan in 1950, where there were 272 cases and 20 deaths after the consumption of semi-dried juvenile sardines. Outbreaks have also occurred in the United States, such as an outbreak in 1971 due to consumption of contaminated crab-meat, where the bacteria are estimated to be responsible for 5000 illnesses annually.

HOST RANGE: Humans, finfish, seafood such as codfish, sardines, mackerel, flounder, clams, octopus, shrimp, crab, lobster, crawfish, scallops, and oysters(1,2,4,5).

INFECTIOUS DOSE: Infection can occur upon ingestion of 107 – 108 organisms(2).

MODE OF TRANSMISSION: Primary mode of transmission is through the ingestion of raw, undercooked, or contaminated shellfish (such as oysters, clams, and mussels). Cooked crustaceans (such as crab, lobster, and shrimp) can still harbour the bacteria if it has not been properly cooked/heated, or if recontamination occurred by coming in contact with uncooked seafood(2). Exposure of open wounds to contaminated seawater, shellfish, or finfish can cause infections and septicaemia(4).

INCUBATION PERIOD: Usually at 15 hours after infection, with a range of 4 – 96 hours(1).

COMMUNICABILITY: Infection cannot be transmitted from person-to-person.


RESERVOIR: V. parahaemolyticus can survive in shellfish during warm seasons, and are naturally part of the flora of bivalve shellfish(2).




DRUG SUSCEPTIBILITY: Susceptibility has been shown for a range of antibiotics such as doxycycline, or ciprofloxacin, tetracycline, ceftriaxone, chloramphenicol, imipenem, ofloxacin, nitrofurantoin, meropenem, oxytetracycline, fluoroquinolones, third generation cephalosporins, and aminoglycosides(2,4,6). Erythromycin may be used by pregnant women and children.

DRUG RESISTANCE: Resistance has been confirmed for penicillin, ampicillin, apramycin, cephalothin, gentamycin, trimethoprim, and streptomycin(6).

SUSCEPTIBILITY TO DISINFECTANTS: Susceptible to 1% sodium hypochlorite, 70% ethanol, 2% glutaraldehyde, and formaldehyde(7).

PHYSICAL INACTIVATION: Extremely sensitive to heat as cells are no longer detectable at 48 – 50 C after 5 minutes; therefore proper cooking of shellfish products can effectively inactivate the bacteria(2). Reduction of the bacteria in seafood can be achieved by cold storage at 3 °C for 7 days, freezing, and low temperature pasteurization; viable cells can be completely inactivated at -18 °C or -24 °C for 15-28 weeks(5). High hydrostatic pressure can also destroy bacterial cells in food without affecting the nature of the food, and irradiation using Cobalt-60 gamma at 0.75 kGy has been shown to reduce bacteria to undetectable levels.

SURVIVAL OUTSIDE HOST: Salinity is crucial for its survival and growth, with multiplication observed at 0.5 – 10%, the optimal level being around 1 – 3%(2). The bacteria can survive through the winter season in marine sediments, and will resume multiplication when temperature rises to at least 15 °C(5), and the bacteria is also highly resistant to metal ions (up to 300 mM Mg2 +). V. parahaemolyticus can enter a viable but non-culturable state in the presence of extreme conditions such as after 12 days of food-starvation or temperature stress around 4 °C.


SURVEILLANCE: Monitor for symptoms and confirm through culturing stool samples of patients suspected of infection(8). Detection of V. parahaemolyticus in foods is commonly done using the most probable number (MPN) method; however, this method cannot differentiate between Vibrio parahaemolyticus, and strains such as Vibrio vulnificus, or Vibrio mimicus as growth of strains that do not ferment sucrose will all appear as similar round (2-3 mm), green or blue colonies on TCBS media (thiosulfate-citrate-bilesalts-sucrose agar). Polymerase chain reaction (PCR), DNA hybridization, and chromogenic medium (plating technique that can detect and distinguished V. parahaemolyticus from other species by its unique purple colonies on the medium) can also be used for detection of contamination or infection(5).

Note: All diagnostic methods are not necessarily available in all countries.

FIRST AID/TREATMENT: Administer appropriate antibiotic therapy. Oral rehydration in infected patients with mild gastroenteritis symptoms, and intravenous fluid and electrolyte replacement should be administered in severe cases(2). Antibiotics should be used for patients with wound infections or septicaemia(4).

IMMUNIZATION: No vaccines are currently available.

PROPHYLAXIS: No drug prophylaxis is currently available. Avoid infection by keeping raw shellfish for consumption at cool temperatures as soon as possible after harvest, as V. paraheamolyticus have been shown to be able to multiply 50-fold in shellfish after 10 hours at 26 C, and 760-fold after 24 hours(2).


LABORATORY-ACQUIRED INFECTIONS: The first laboratory-acquired infection was recorded in 1972 when a worker was subculturing different strains of the bacteria(8), and another infection was reported in 2002, and was caused through handling experimentally infected abalones(9).

SOURCES/SPECIMENS: Stool samples, contaminated seawater and seafood(2,8).

PRIMARY HAZARDS: Major hazards in the laboratory are ingestion and accidental parenteral inoculation(10).

SPECIAL HAZARDS: Naturally and experimentally infected animals are potential sources of infection(4,9).



CONTAINMENT REQUIREMENTS: Containment Level 2 facilities, equipment, and operational practices for work involving infectious or potentially infectious materials, animals, or cultures.

PROTECTIVE CLOTHING: Lab coat. Gloves when direct skin contact with infected materials or animals is unavoidable. Eye protection must be used where there is a known or potential risk to splashes(11).

OTHER PRECAUTIONS: All procedures that may produce aerosols, or involve high concentrations or large volumes should be conducted in a biological safety cabinet (BSC)(11). The use of needles, syringes and other sharp objects should be strictly limited. Additional precautions should be considered with work involving animals or large scale activities(11).


SPILLS: Allow aerosols to settle and, wearing protective clothing, gently cover spill with paper towels and apply appropriate disinfectant, starting at the perimeter and working towards the centre. Allow sufficient contact time before clean up (30 min)(11).

DISPOSAL: Decontaminate all wastes that contain or have come in contact with the infectious organism before disposing by autoclave, chemical disinfection, gamma irradiation, or incineration(11).

STORAGE: Properly labelled and sealed containers(11).


REGULATORY INFORMATION: The import, transport, and use of pathogens in Canada is regulated under many regulatory bodies, including the Public Health Agency of Canada, Health Canada, Canadian Food Inspection Agency, Environment Canada, and Transport Canada. Users are responsible for ensuring they are compliant with all relevant acts, regulations, guidelines, and standards.

UPDATED: September 2010

PREPARED BY: Pathogen Regulation Directorate, Public Health Agency of Canada

Although the information, opinions and recommendations contained in this Pathogen Safety Data Sheet are compiled from sources believed to be reliable, we accept no responsibility for the accuracy, sufficiency, or reliability or for any loss or injury resulting from the use of the information. Newly discovered hazards are frequent and this information may not be completely up to date.

Copyright © Public Health Agency of Canada, 2010 Canada

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