Cholera is caused by an infection of the intestine with the bacterium Vibrio cholerae. The bacterium causes the cells lining the intestine to produce large amounts of fluid, leading to profuse diarrhoea and vomiting.
 
The infection spreads when someone ingests food or water contaminated with the faeces or vomit of someone carrying the disease. Contaminated food or water supplies can cause massive outbreaks in a short period of time, particularly in overcrowded areas such as slums or refugee camps.

Typically, symptoms of cholera appear within two to three days of infection. However, it can take anywhere from a few hours to five days or longer for symptoms to appear.
A cholera infection is often mild or without symptoms but can sometimes be severe, resulting in profuse watery diarrhoea, vomiting and leg cramps.
 
The patient rapidly loses body fluids, leading to dehydration and shock. Without treatment, they may die within hours.

Cholera can be diagnosed by examining stool samples or rectal swabs but, due to the fast-acting nature of the disease, there is often little time to do so.

In epidemic situations, a diagnosis is often made by taking a patient's history and conducting a brief examination, with treatment given before there is time for a laboratory to confirm the diagnosis.

Cholera can be treated simply and successfully by immediately replacing the fluids and salts lost through vomiting and diarrhoea – with prompt rehydration, less than one per cent of cholera patients die.

Cholera victims are always treated with oral rehydration solutions - prepackaged mixtures of sugars and salts that are mixed with water and drunk in large amounts. Severe cases will need these fluids to be replaced intravenously via a drip, and antibiotics are sometimes administered.