Cholera is a bacterial infection caused by drinking contaminated water or eating food that has been in contact with contaminated water.
Not everyone who becomes infected will develop symptoms, but those who do will usually experience:
severe, watery diarrhoea
feeling and being sick
These symptoms generally develop within a few days of infection, although they can sometimes occur after only a few hours.
Without treatment, the combination of diarrhoea and vomiting can cause a person to quickly become dehydrated and go into shock (where there is a sudden massive drop in blood pressure). In the most severe cases, the condition can be fatal.
Cholera can spread if food and water in particular becomes contaminated with the stools (faeces) of someone with the infection. This is why the condition is most common in regions of the world with poor sanitation, such as parts of:
south and south-east Asia
the Middle East
central America and the Caribbean
Mass outbreaks of cholera can occur in times of a natural disaster or war, as a result of overcrowding in poor living conditions and a lack of access to clean water.
The World Health Organization estimates that there are between 3 and 5 million cases of cholera worldwide every year.
There have been no cases of cholera originating in England and Wales for over 100 years, although travellers do occasionally bring the infection back with them. This is rare, however, with only 12 reported cases in England and Wales during 2012.
Advice for travellers
If you are travelling to parts of the world known to be affected by cholera, following basic precautions should prevent you from contracting a cholera infection and other causes of traveller’s diarrhoea:
only drink water that has been recently boiled, or drink from a bottle that is properly sealed
avoid ice cream and don't have ice in your drinks
avoid uncooked fruits and vegetables unless you have washed them in safe water or peeled them yourself
avoid shellfish, seafood or salads
Vaccination against cholera may sometimes be recommended if you are travelling to areas where the infection is widespread, particularly if you're an aid worker and likely to have limited access to medical services.
Speak to a nurse or doctor about whether you need a cholera vaccination well in advance of travelling if you are considering visiting an area affected by cholera.
The cholera vaccine is available as a drink, which is given in two or three separate doses that are taken between one and six weeks apart.
The vaccine is estimated to be about 85% effective in the months following vaccination, although the level of protection gradually reduces over time and booster doses will eventually be needed if you continue to be at risk.
Cholera needs prompt treatment with oral rehydration solution (ORS) to prevent dehydration and shock. ORS comes as a sachet containing a mixture of salts and glucose, which is designed to be dissolved in water. ORS is ideal for replacing the fluids and minerals that are lost when a person becomes dehydrated.
As well as treating dehydration and shock with ORS, antibiotics are sometimes used to treat the underlying infection.
ORS sachets are available from many pharmacists, camping shops and travel clinics. If you are travelling to regions of the world affected by cholera, take ORS sachets as a precaution.
There is a vaccination available to protect you against cholera when travelling, although most people will not need it because food and water hygiene precautions are normally enough to prevent infection.
Vaccination is usually only recommended for travellers to areas where cholera is widespread, particularly for aid workers and people likely to have limited access to medical services.
It is also available through private prescription from a private travel clinic.
The cholera vaccine is given as a drink, where the vaccination ingredients are mixed with water. You should avoid eating, drinking or taking oral medication for an hour before and after having the vaccination.
For adults and children over the age of six, two doses of the vaccine are needed to protect against cholera for two years. After this, a booster is required if you continue to be at risk.
Children aged two to six years old will need to have three doses of the vaccine. This will protect them for six months, after which time they will need to have a booster if they continue to be at risk.
All the doses must be taken between one and six weeks apart. If more than six weeks passes between your doses, you will need to start the full vaccination course again.
Ideally, the vaccinations should be completed at least one week before travelling.
The cholera vaccine is not recommended for children under two years of age because it is not clear how well it works in this age group.
Side effects and precautions
After having the cholera vaccine, less than one in every 100 people will experience short-term symptoms similar to a mild stomach upset, such as abdominal (tummy) pain, diarrhoea and nausea. Severe reactions are very rare.
Most people can have the vaccination safely, but you should tell the doctor or nurse before being vaccinated if:
you have a high temperature (fever) or stomach upset
you are pregnant or think you might be pregnant
you are breastfeeding
you have a condition, or are receiving treatment, that affects your immune system
In these circumstances you may still be able to have the vaccine if you are at a high risk of cholera, but your doctor or nurse may need to check with a travel medicine specialist before giving it to you. The vaccination may need to be delayed if you are unwell with a fever or upset stomach.
You should not have the vaccine if you have had an allergic reaction to the cholera vaccine or any of the vaccine components in the past.
Reporting side effects
The Yellow Card Scheme allows you to report suspected side effects from any type of medicine you are taking. It is run by a medicines safety watchdog called the Medicines and Healthcare products Regulatory Agency (MHRA).
See the Yellow Card Scheme website for more information.