364 ◾ Fundamental Food Microbiology
KP + because of their ability to cause hemolysis when grown on Wagatsuma agar. KP + strains
are pathogenic while KP – strains are generally nonpathogenic. Most strains isolated from natural
sources (estuarine water, plankton, shellfish, and finfish) are Kanagawa-negative. However, some
Kanagawa-negative strains have also been associated with foodborne outbreaks. All pathogenic
strains were found to adhere to human fetal intestinal cells in cell cultures. The toxin production
rate and its level are directly related to cell growth, cell concentrations, and pH of the environment. Heating does not destroy the toxin that is formed (in a food).
Disease and Symptoms 42
The cells are sensitive to low stomach pH. Generally, an individual has to consume 10 5–7 cells of
a Kanagawa-positive strain for symptoms to develop. However, an increase in pH from consumption of bicarbonates and foods can reduce the infective dose. Once Vib. parahaemolyticus reach the
intestine, it adheres/colonizes epithelial cells, using a multivalent adhesion molecule (MAM). Iron
acquisition using siderophore (vibrioferrin) is also important for bacterial survival and growth.
Bacteria secrete hemolysins (TDH and TRH) and form pores in epithelial cells. The relatively
large pore size allows both water and ions to flow through a membrane. Symptoms appear 10–24
hours following ingestion of live cells and last for two to three days. Symptoms include nausea,
vomiting, abdominal cramps, watery diarrhea, headache, fever, and chills. Sometimes, it may
cause bloody diarrhea. The disease is not normally fatal. But systemic spread of the organism in
blood may lead to septicemia resulting in organ failure, shock, and death.
Food Association
Vib. parahaemolyticus strains have been isolated in high numbers from various types of seafoods
harvested from estuarine environments, especially during the summer months. The outbreaks,
as well as sporadic cases of gastroenteritis, were linked to the consumption of raw, improperly
cooked, or post-heat-contaminated seafoods, including fish (mackerels, sardines, codfish), oysters,
crabs, shrimp, clams, octopus, and lobsters. In unrefrigerated raw and cooked seafoods, Vib. parahaemolyticus can grow rapidly, especially at 20°C–30°C. In temperature-abused seafoods, cells can
reach an infective dose level very rapidly even from a low initial population. Many outbreaks in
the United States were identified as being a result of inadequate cooking and cross-contamination
of cooked seafoods, followed by improper holding temperatures.
Prevention
Several factors need to be considered in controlling gastroenteritis from Vib. parahaemolyticus.
The seafoods harvested from an estuary should be assumed to contain Vib. parahaemolyticus,
some strains of which can be pathogenic. In unrefrigerated raw, improperly heated, or postheat-contaminated seafood, the cells can multiply rapidly. Once the pathogenic strains grow to
infective numbers, even heat treatment cannot destroy the toxin. With this understanding, the
control methods should include the following: no consumption of raw seafoods, proper heat
treatment of seafoods, proper sanitation to avoid cross-contamination of heated foods, proper
refrigeration of raw and heated products, and consumption of the food within a reasonable
period of time. Temperature abuse, even for a short duration, of a seafood should be avoided.
Persons with chronic liver disease should avoid raw oysters to prevent Vib. parahaemolyticus
infection.
KP + because of their ability to cause hemolysis when grown on Wagatsuma agar. KP + strains
are pathogenic while KP – strains are generally nonpathogenic. Most strains isolated from natural
sources (estuarine water, plankton, shellfish, and finfish) are Kanagawa-negative. However, some
Kanagawa-negative strains have also been associated with foodborne outbreaks. All pathogenic
strains were found to adhere to human fetal intestinal cells in cell cultures. The toxin production
rate and its level are directly related to cell growth, cell concentrations, and pH of the environment. Heating does not destroy the toxin that is formed (in a food).
Disease and Symptoms 42
The cells are sensitive to low stomach pH. Generally, an individual has to consume 10 5–7 cells of
a Kanagawa-positive strain for symptoms to develop. However, an increase in pH from consumption of bicarbonates and foods can reduce the infective dose. Once Vib. parahaemolyticus reach the
intestine, it adheres/colonizes epithelial cells, using a multivalent adhesion molecule (MAM). Iron
acquisition using siderophore (vibrioferrin) is also important for bacterial survival and growth.
Bacteria secrete hemolysins (TDH and TRH) and form pores in epithelial cells. The relatively
large pore size allows both water and ions to flow through a membrane. Symptoms appear 10–24
hours following ingestion of live cells and last for two to three days. Symptoms include nausea,
vomiting, abdominal cramps, watery diarrhea, headache, fever, and chills. Sometimes, it may
cause bloody diarrhea. The disease is not normally fatal. But systemic spread of the organism in
blood may lead to septicemia resulting in organ failure, shock, and death.
Food Association
Vib. parahaemolyticus strains have been isolated in high numbers from various types of seafoods
harvested from estuarine environments, especially during the summer months. The outbreaks,
as well as sporadic cases of gastroenteritis, were linked to the consumption of raw, improperly
cooked, or post-heat-contaminated seafoods, including fish (mackerels, sardines, codfish), oysters,
crabs, shrimp, clams, octopus, and lobsters. In unrefrigerated raw and cooked seafoods, Vib. parahaemolyticus can grow rapidly, especially at 20°C–30°C. In temperature-abused seafoods, cells can
reach an infective dose level very rapidly even from a low initial population. Many outbreaks in
the United States were identified as being a result of inadequate cooking and cross-contamination
of cooked seafoods, followed by improper holding temperatures.
Prevention
Several factors need to be considered in controlling gastroenteritis from Vib. parahaemolyticus.
The seafoods harvested from an estuary should be assumed to contain Vib. parahaemolyticus,
some strains of which can be pathogenic. In unrefrigerated raw, improperly heated, or postheat-contaminated seafood, the cells can multiply rapidly. Once the pathogenic strains grow to
infective numbers, even heat treatment cannot destroy the toxin. With this understanding, the
control methods should include the following: no consumption of raw seafoods, proper heat
treatment of seafoods, proper sanitation to avoid cross-contamination of heated foods, proper
refrigeration of raw and heated products, and consumption of the food within a reasonable
period of time. Temperature abuse, even for a short duration, of a seafood should be avoided.
Persons with chronic liver disease should avoid raw oysters to prevent Vib. parahaemolyticus
infection.