Bad Bug Book:
Foodborne Pathogenic Microorganisms and Natural Toxins Handbook
Vibrio cholerae Serogroup O1
Vibrio cholerae Serogroup O1
This bacterium is responsible for Asiatic or epidemic cholera. No major outbreaks of this disease have occurred in the United States since 1911. However, sporadic cases occurred between 1973 and 1991, suggesting the possible reintroduction of the organism into the U.S. marine and estuarine environment. The cases between 1973 and 1991 were associated with the consumption of raw shellfish or of shellfish either improperly cooked or re-contaminated after proper cooking. Environmental studies have demonstrated that strains of this organism may be found in the temperate estuarine and marine coastal areas surrounding the United States.
In 1991 cholera was reported for the first time in this century in South America, starting in Peru. The outbreaks quickly grew to epidemic proportions and spread to other South American and Central American countries, and into Mexico. 1,099,882 cases and 10,453 deaths were reported in the Western Hemisphere between January 1991 and July 1995.
Although the South American strain of V. cholerae O1 has been isolated from Gulf Coast waters, presumably transmitted by ships off-loading contaminated ballast water, no cases of cholera have been attributed to fish or shellfish harvested from U.S. waters. However, over 100 cases of cholera caused by the South American strain have been reported in the United States. These cases were travelers returning from South America, or were associated with illegally smuggled, temperature-abused crustaceans from South America.
In the Autumn of 1993, a new strain, a non-O1 never before identified, was implicated in outbreaks of cholera in Bangladesh and India. The organism, V. cholerae serogroup O139 (Bengal), causes characteristic severe cholera symptoms. Previous illness with V. cholerae O1 does not confer immunity and the disease is now endemic. In the U.S., V. cholerae O139 has been implicated in one case, a traveller returning from India. The strain has not been reported in U.S. waters or shellfish.
Cholera is the name of the infection caused by V. cholerae.
Symptoms of Asiatic cholera may vary from a mild, watery diarrhea to an acute diarrhea, with characteristic rice water stools. Onset of the illness is generally sudden, with incubation periods varying from 6 hours to 5 days. Abdominal cramps, nausea, vomiting, dehydration, and shock; after severe fluid and electrolyte loss, death may occur. Illness is caused by the ingestion of viable bacteria, which attach to the small intestine and produce cholera toxin. The production of cholera toxin by the attached bacteria results in the watery diarrhea associated with this illness.
Infective dose -- Human volunteer feeding studies utilizing healthy individuals have demonstrated that approximately one million organisms must be ingested to cause illness. Antacid consumption markedly lowers the infective dose.
Cholera can be confirmed only by the isolation of the causative organism from the diarrheic stools of infected individuals.
Cholera is generally a disease spread by poor sanitation, resulting in contaminated water supplies. This is clearly the main mechanism for the spread of cholera in poor communities in South America. The excellent sanitation facilities in the U.S. are responsible for the near eradication of epidemic cholera. Sporadic cases occur when shellfish harvested from fecally polluted coastal waters are consumed raw. Cholera may also be transmitted by shellfish harvested from nonpolluted waters since V. cholerae O1 is part of the autochthonous microbiota of these waters.
Over 200 proven cases of cholera have been reported in the U.S. since 1973, with 90% occurring within the last 5 years. Most of these cases were detected only after epidemiological investigation. Probably more sporadic cases have occurred, but have gone undiagnosed or unreported.
Individuals infected with cholera require rehydration either intravenously or orally with a solution containing sodium chloride, sodium bicarbonate, potassium chloride, and dextrose (glucose). The illness is generally self-limiting. Antibiotics such as tetracycline have been demonstrated to shorten the course of the illness. Death occurs from dehydration and loss of essential electrolytes. Medical treatment to prevent dehydration prevents all complications.
All people are believed to be susceptible to infection, but individuals with damaged or undeveloped immunity, reduced gastric acidity, or malnutrition may suffer more severe forms of the illness.
V. cholerae serogroup O1 and O139 may be recovered from foods by methods similar to those used for recovering the organism from the feces of infected individuals. Pathogenic and non-pathogenic forms of the organism exist, so all food isolates must be tested for the production of cholera enterotoxin.
For more information on recent outbreaks see the Morbidity and Mortality Weekly Reports from CDC.
Literature references can be found at the links below.
CDC brochures on the prevention of cholera.
Cholera Prevention FAQ's
Center for Disease Control and Prevention of Food Illness Fact Sheet
"Produce Handling and Processing Practices" (1997) Emerging Infectious Diseases 3(4).
In the past decade, outbreaks of human illness associated with the consumption of raw vegetables and fruits (or unpasteurized products produced from them) have increased in the United States. Pathogens such as Listeria monocytogenes, Clostridium botulinum, and Bacillus cereus are naturally present in some soil, and their presence on fresh produce is not rare. Salmonella, Escherichia coli O157:H7, Campylobacter jejuni, Vibrio cholerae, parasites, and viruses are more likely to contaminate fresh produce through vehicles such as raw or improperly composted manure, irrigation water containing untreated sewage, or contaminated wash water. Treatment of produce with chlorinated water reduces populations of pathogenic and other microorganisms on fresh produce but cannot eliminate them. Reduction of risk for human illness associated with raw produce can be better achieved through controlling points of potential contamination in the field; during harvesting; during processing or distribution; or in retail markets, food-service facilities, or the home.
Loci index for genome Vibrio cholerae
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.