Cholera: Causes and symptoms

Cholera is an acute, diarrheal illness caused by the bacterium Vibrio cholerae. Of the more than 200 recognized V, cholerae serogroups, only cholera toxin-producing O1 and O139 serogroups have caused large epidemics and are defined as causing cholera.

A person may get cholera by drinking water or eating food that is contaminated with the cholera bacterium.

The source of the contamination is usually the feces of an infected person, or water contaminated with sewage. Cholera primarily occurs in settings where there is inadequate access to clean water and sanitation.

Cholera is characterized by copious watery diarrhea, without abdominal cramps or fever. Most individuals infected with toxigenic V. cholerae O1 have no symptoms, and some have only mild to moderate diarrhea lasting 3 to 7 days.

People exposed to cholera may experience mild profuse vomiting and dehydration. Cholera diarrhea can look like cloudy rice water.

Cholera can cause death from dehydration (the loss of water and salts from the body) within hours if not treated.
Cholera: Causes and symptoms

Food-borne pathogenic bacteria: Vibrio cholerae

Vibrio cholerae belonging to O1 and O139 sero-groups cause cholera, a life threatening diarrheal disease that spreads through consumption of water and food contaminated with the pathogen. Vibrio cholerae O1 is the causative agent of cholera.

Although Vibrio cholerae is a human pathogen, the bacteria are part of the normal aquatic flora in estuarine and brackish waters and thus are able to persist in the environment outside human host.

Cholera was originally endemic in eastern India. Up to 1960, it had extended from India in six pandemics over the world.

Vibrio cholerae is a motile rod with a single polar, sheathed flagellum. It can grow in peptone water with 6% NaCl.

Although cholera is considered a waterborne disease, there is an evidence indicates the importance of food, particularly seafood, in the transmission of cholera.

The physicochemical characteristics of foods that support survival and growth of Vibrio cholerae O1 are high moisture content, neutral or alkaline pH, low temperature, high organic content and an absence of other competing bacteria.

Pathogenic vibrios are capable of producing three clinical manifestations of infection: gastroenteritis, soft tissue infections and systemic infections in including bacteremia.
Food-borne pathogenic bacteria: Vibrio cholerae

The bacteria of Vibrio cholerae

Vibrio cholerae belongs to a group of organisms whose natural habitats are the aquatic ecosystems.

It is a facultative anaerobic, Gram-negative rods, motile by polar flagella in liquid media but peritrichous flagella may be produced on solid media in some species.

The bacterium is oxidase-positive, reduces nitrate, and is motile by means of a single, sheathed, polar flagellum.

The Vibrio genus is part of the family Vibrionaceae. The family also includes the genera Photobacterium, Aeromonas and Plesiosomonas.

Vibrio cholerae is the causative agent of cholera, an acute life- threatening diarrheal disease which occurs in many developing countries, particularly in South Asia, Africa and Latin America. Infection due to Vibrio cholerae begins with ingestion of contaminated water or food.

After passage through the acid barrier of the stomach, the organism colonizes the epithelium of the small intestine by means of the toxin-coregulated pili.

Attached Vibrio cholerae begin cell division and when sufficient numbers of cells have accumulated, they begin to produce an enterotoxin called cholera toxin which causes severe diarrhea.
The bacteria of Vibrio cholerae