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   Vibrio cholerae (micro-organism)
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    Taxonomic name: Vibrio cholerae (Pacini, 1854)
    Synonyms:
    Common names: Asiatic cholera (English), epidemic cholera (English)
    Organism type: micro-organism
    Vibrio cholerae is the bacteria that causes cholera; a potentially epidemic and life-threatening secretory diarrhea characterised by numerous, voluminous watery stools, often accompanied by vomiting and resulting in hypovolemic shock and acidosis. It can also cause mild or unapparent infections. Vibrio cholerae occurs in both marine and freshwater habitats in mutualistic associations with aquatic animals. Vibrio cholerae is endemic or epidemic in areas with poor sanitation; it occurs sporadically or as limited outbreaks in developed countries. Cholera is transmitted by the fecal-oral route. In coastal regions it may persist in shellfish and plankton. Long-term convalescent carriers are rare.
    Description
    According to Todar (2002), Vibrio cholerae consists of gram-negative, straight- or curved-rod bacteria. The bacteria are bioluminescent and motile by means of a single polar flagellum. Vibrio spp. are capable of both respiratory and fermentative metabolism. Oxygen is a universal electron acceptor, and they do not denitrify. Most Vibrio spp. are oxidase-positive. There are 3 antigenic types (Inaba, Ogawa, and Hikojima) and the distinct El Tor biotype.
    Similar Species
    Vibrio parahaemolyticus

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    Occurs in:
    estuarine habitats, lakes, marine habitats, water courses, wetlands
    Habitat description
    According to WHO (2000), V. cholerae is often found in the aquatic environment and is part of the normal flora of brackish water and estuaries. It is often associated with algal blooms (plankton), which are influenced by the temperature of the water. Todar (2002) notes that Vibrio spp. are typically marine organisms, so most species require 2-3% NaCl or a seawater base for optimal growth; however, V. cholerae occurs in both marine and freshwater habitats in mutualistic associations with aquatic animals. V. cholerae is the most important Vibrio sp. to humans, although other species are pathogenic for invertebrates and other vertebrates. Finkelstein (UNDATED) notes that in coastal regions it may persist in shellfish and plankton. V. cholerae is endemic or epidemic in areas with poor sanitation, but long-term convalescent carriers are rare.
    General impacts
    Cholera is caused by certain members of the species Vibrio cholerae, which can also cause mild or unapparent infections (Finkelstein, UNDATED). According to Todar (2002), V. cholerae produces cholera toxin, the model for enterotoxins, whose action on the mucosal epithelium is responsible for the characteristic diarrhea of the disease cholera. In its extreme manifestation, cholera is one of the most rapidly fatal illnesses known. A healthy person may become hypotensive within an hour of the onset of symptoms and may die within 2-3 hours if no treatment is provided. More commonly, the disease progresses from the first liquid stool to shock in 4-12 hours, with death following in 18 hours to several days. The clinical description of cholera begins with sudden onset of massive diarrhea. The patient may lose gallons of protein-free fluid and associated electrolytes, bicarbonates, and ions within a day or two. This loss of fluid leads to dehydration, anuria, acidosis, and shock. The watery diarrhea is speckled with flakes of mucus and epithelial cells ("rice-water stool") and contains enormous numbers of bacteria. The loss of potassium ions may result in cardiac complications and circulatory failure. Untreated cholera frequently results in high (50-60%) mortality rates.
    Geographical range
    According to Todar (2002), Vibrio spp. are some of the most common organisms in surface waters of the world. V. cholerae is causing epidemic cholera in parts of Latin America, Africa, and Asia (CDC, 2001). It occurs sporadically or as limited outbreaks in developed countries (Finkelstein, UNDATED).
    Introduction pathways to new locations
    Live food trade: The U.S. Food and Drug Administration is testing imported and domestic shellfish and monitoring the safety of U.S. shellfish beds through the shellfish sanitation program (CDC, 2001).
    Other: Transmission is through contaminated food or water sources (Todar, 2002).
    People sharing resources: V. cholerae is endemic or epidemic in areas with poor sanitation (Finkelstein, UNDATED).


    Local dispersal methods
    Consumption/excretion: V. cholerae is spread by the human fecal-oral route (Todar, 2002).
    Management information
    According to Todar (2002), treatment of cholera involves the rapid intravenous replacement of the lost fluid and ions. Following this replacement, administration of isotonic maintenance solution should continue until the diarrhea ceases. If glucose is added to the maintenance solution it may be administered orally, thereby eliminating the need for sterility and intravenous administration. By this simple treatment regimen, patients on the brink of death seem to be miraculously cured and the mortality rate of cholera can be reduced more than ten-fold. Most antibiotics and chemotherapeutic agents have no value in cholera therapy, although a few (e.g. tetracyclines) may shorten the duration of diarrhea and reduce fluid loss. The CDC (2001) indicates that international public health authorities are working to enhance surveillance for cholera, investigate cholera outbreaks, and design and implement preventive measures.
    Nutrition
    Todar (2002) explains that most Vibrio spp. have relatively simple growth factor requirements and will grow in synthetic media with glucose as a sole source of carbon and energy.
    Reproduction
    Cell division is by an asexual process called binary fission, which is the process of the division of a single-celled organism into two daughter cells (Anderson, 1999).
    Reviewed by: Anon
    Compiled by: National Biological Information Infrastructure (NBII) & IUCN/SSC Invasive Species Specialist Group (ISSG)
    Last Modified: Thursday, 23 March 2006


ISSG Landcare Research NBII IUCN University of Auckland