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An acute diarrhoeal infection caused by toxigenic Vibrio cholerae bacteria in contaminated water or food, which can kill within hours but is treatable with oral rehydration.
Cholera is an acute diarrhoeal disease caused by infection of the intestine with toxigenic strains of the bacterium Vibrio cholerae, a comma-shaped, gram-negative organism spread mainly through water or food contaminated with human faeces. Of the many serogroups of the bacterium, only two — O1 and O139 — cause epidemics. The bacterium itself does not invade the body; it colonises the small intestine and releases cholera toxin, which forces the intestinal cells to pump out water and salts, producing the characteristic painless, watery 'rice-water' stools. Most infections are mild or without symptoms, but in severe cases an adult can lose litres of fluid in hours and die of dehydration and shock within a day if untreated. The disease is therefore a marker of failed water and sanitation systems rather than of any exotic pathogen, and the World Health Organization treats it as a disease of poverty and inequity.
Type: PhenomenonCause — toxigenic Vibrio cholerae, serogroups O1 (dominant worldwide) and O139 (the 'Bengal' serogroup); other serogroups do not cause epidemics
Transmission — the faecal-oral route, through drinking water, contaminated food, or seafood from polluted waters; it is not spread by casual contact
Incubation — roughly 12 hours to 5 days after ingestion, which allows the disease to travel with people before it announces itself
Symptoms — profuse painless watery diarrhoea described as 'rice-water' stools, vomiting, muscle cramps and rapid dehydration
Treatment — oral rehydration solution (ORS) alone saves the large majority of patients; severe cases need intravenous fluids, and antibiotics shorten severe illness; zinc supplements are given to children
Prevention — safe drinking water, sanitation and hygiene (WASH), plus oral cholera vaccines (OCVs) in outbreaks and high-risk areas
Endemic in India, with a clear seasonal pattern tied to the monsoon, floods and contamination of drinking water sources
Frequency: A standard science-and-public-health topic in SSC and railway papers, and a recurring current-affairs theme whenever outbreaks or vaccine shortages make news
Cholera's severity comes from a single toxin acting on the small intestine, which is why rehydration works so well as treatment.
Step 1: A person swallows water or food carrying toxigenic Vibrio cholerae, usually contaminated by the faeces of an infected person
Step 2: Bacteria that survive stomach acid reach the small intestine and attach to its lining without invading the bloodstream
Step 3: They release cholera toxin, which switches on a cellular pathway that pushes chloride ions and water out of the cells into the gut
Step 4: Litres of fluid pour out as painless watery diarrhoea, carrying salts with it; dehydration, low blood pressure and shock can follow within hours
Step 5: Oral rehydration solution replaces the lost water and electrolytes, using glucose to drag sodium and water back across the gut wall; severe cases need intravenous fluid
Step 6: The patient excretes bacteria for days, so unsafe sanitation returns them to the water supply and the cycle repeats
Cholera has shaped public health more than almost any other disease — it produced modern epidemiology, the sanitary movement and, much later, oral rehydration therapy.
John Snow maps deaths around the Broad Street pump in London and links cholera to contaminated water
Robert Koch isolates Vibrio cholerae
The seventh and current pandemic begins, driven by the El Tor biotype
Dilip Mahalanabis uses oral rehydration solution at scale in refugee camps during the Bangladesh war, proving it can replace intravenous fluids
Serogroup O139 'Bengal' emerges in India and Bangladesh
The GTFCC launches 'Ending Cholera: A Global Roadmap to 2030'
A global surge in outbreaks empties the vaccine stockpile; WHO shifts to a one-dose emergency strategy and preventive campaigns are suspended
WHO announces that preventive vaccination can resume as supply recovers, with Mozambique the first country to restart
Vibrio cholerae, serogroups O1 and O139
12 hours to 5 days
More than 600,000 cases of cholera or acute watery diarrhoea and nearly 7,600 deaths from 33 countries (WHO; an underestimate, as cholera is under-reported)
105,813 cases and 1,216 deaths worldwide between 1 January and 22 June 2026
About 35 million doses a year in 2022, rising to nearly 70 million in 2025
One dose protects for at least six months; two doses for up to three years
90 per cent reduction in cholera deaths and elimination in up to 20 countries by 2030
Global Task Force on Cholera Control (GTFCC)
Coordinates the global cholera strategy and the 2030 roadmap; a network of UN agencies, academic institutions and NGOs
World Health Organization (WHO)
Surveillance, outbreak response and prequalification of oral cholera vaccines
Integrated Disease Surveillance Programme (IDSP)
Detects and reports outbreaks of cholera and other communicable diseases in India
ICMR-National Institute of Cholera and Enteric Diseases (NICED)
India's specialised research institute on cholera and enteric infections
Cholera is a disease with a known cause, a cheap cure and an effective vaccine, and it still kills thousands of people a year — which makes it an index of how well water and sanitation reach the poorest. That is exactly why it recurs in exam papers: it links science with Sustainable Development Goal 6 on water and sanitation, with disaster management after floods and cyclones, and with India's own WASH programmes. The 2022-2025 vaccine shortage also carries a policy lesson about a market with too few manufacturers: when demand surged, the global stockpile emptied and the world had to halve doses to stretch supply, and preventive campaigns stopped for three years. For India, which is home to endemic transmission and to one of the manufacturers of oral cholera vaccine, the relevant questions are surveillance, safe drinking water and outbreak response after floods.
Cholera = acute watery diarrhoea from toxigenic Vibrio cholerae; epidemic serogroups O1 and O139
Spread by the faecal-oral route through contaminated water and food; incubation 12 hours to 5 days
Cholera toxin makes the gut secrete fluid — hence 'rice-water' stools and rapid dehydration
ORS is the mainstay of treatment; severe cases need IV fluids and antibiotics, children also get zinc
John Snow 1854 (Broad Street pump); Robert Koch 1883 (isolated the organism); seventh pandemic since 1961 (El Tor); O139 Bengal in 1992-93
GTFCC roadmap: 90 per cent fewer deaths and elimination in up to 20 countries by 2030
OCV supply doubled from 35 million doses (2022) to nearly 70 million (2025); one dose is the outbreak standard; preventive campaigns resumed in 2026
Shanchol, a bivalent killed oral vaccine, was developed in India by Shantha Biotechnics, Hyderabad
Toxigenic strains of the bacterium Vibrio cholerae, mainly serogroups O1 and O139, swallowed in water or food contaminated with human faeces.
Chiefly with oral rehydration solution, which replaces lost water and salts. Severe cases need intravenous fluids and antibiotics, and children are also given zinc.
Yes. Oral cholera vaccines are used in outbreaks and high-risk areas. One dose protects for at least six months and two doses for up to three years; global supply nearly doubled between 2022 and 2025.
Cholera toxin makes intestinal cells pump out water and salts without damaging them, so the stool is a pale, watery fluid flecked with mucus rather than blood — it looks like water in which rice has been washed.
Yes, cholera is endemic in parts of India, with outbreaks clustering in the monsoon and after floods when drinking water sources are contaminated. Cases are reported through the Integrated Disease Surveillance Programme.