Cholera
What is cholera?
Cholera is an acute diarrhoeal illness caused by a bacterium (bug) Vibrio cholerae. It causes painless diarrhoea and vomiting. Most people (9 out of 10) who get cholera have uncomplicated diarrhoea and vomiting or no symptoms at all. About 1 in 10 people who get cholera will develop severe symptoms such as watery diarrhoea, vomiting, and leg cramps. For these people, rapid loss of body fluids leads to dehydration and shock. Without treatment, death can occur within hours.
Cholera is a notifiable disease in Ireland.
How do you get cholera?
People usually get cholera by drinking contaminated water or by eating contaminated food. Sudden large outbreaks are usually caused by a contaminated water supply, where poor or non-existent sewage systems allow human faeces (poo) to get into the drinking water supply.
Cholera may also be transmitted by food. Cholera bugs can live in estuaries and coastal waters where shellfish are grown. People can get cholera if they eat raw or undercooked shellfish grown in a place where cholera bugs live. This has happened in the US, where people in Gulf Coast States have gotten cholera from eating raw or undercooked shellfish.
Person to person spread is uncommon, usually the disease spreads only when the faeces (poo) of a person who has cholera gets into other people’s drinking water or food. Cholera is not likely to spread in countries like Ireland where people have access to safe drinking water and good washing and toilet facilities. The greatest protection against cholera is safe clean chlorinated drinking water, uncontaminated by sewage.
How serious is cholera?
Cholera is more likely to cause death in countries where it is endemic (where cholera is common). Most people who get cholera will have no or mild symptoms and can be successfully treated by drinking oral rehydration solution. Severe cases often need speedy treatment with intravenous fluids and antibiotics (a drip). Normally, when people get early treatment for dehydration, they make a full recovery.
In countries like Ireland, with few cases and advanced healthcare systems, speedy treatment of dehydration and shock means that cholera does not normally cause death. In fact, the death rate for cholera in countries like Ireland and the US is less than that for disease due to E.coli O157 or salmonellosis.
How common is cholera?
Each year, lots of people get cholera (between 1 million and 4 million cases of cholera worldwide each year). However, cholera is very uncommon in Europe. In Western Europe, cases are usually in people returning from abroad, from endemic areas (areas where cholera is common).
Cholera is very uncommon in Ireland. About 1 or 2 people with cholera are seen each year in Ireland. People with cholera in Ireland have normally caught it while they were outside the country.
Is there more cholera now than in the past?
Up until about 100 years ago, cholera was very common in Ireland, Britain, Europe and the US (mostly in cities and towns). Cholera is no longer common in these places.
Over the past few years the number of people with cholera in Ireland and Europe has risen slightly. This small increase in numbers of people with cholera in Ireland and Europe is related to more people travelling to areas where cholera is endemic (areas where cholera is common).
Where is cholera found?
Cholera is mainly found in tropical parts of Africa and Asia, and in Mexico, mainly in places where people do not have safe drinking water and good washing and toilet facilities. In many countries, people do not have safe drinking water, washing facilities, or sewage systems. This can be because of war, or because there is not enough money to build these services.
Can cholera be treated?
Cholera is easily treated by giving the person fluids and salts. This is to replace the person’s fluids and salts which are lost through diarrhoea. During big outbreaks (epidemics) in less developed countries, most people (9 out of 10) can be completely treated by taking fluids and salts by mouth (drinking). This is done by drinking oral rehydration solution. About 1 in 10 people with cholera get severe symptoms and will need a drip (intravenous fluids) to replace the fluid they have lost.
What can you do to protect yourself against cholera?
You are really only at risk from cholera while travelling in less developed countries where the disease is endemic (widespread). Even in endemic areas, the risk for travellers is low. The best way to protect yourself and others while abroad is to wash your hands often and to ensure your food and water are safe for use. Washing your hands after using the toilet, before preparing food and before eating or drinking anything is very important. Only drink bottled water, or tap water that has been boiled. And only brush your teeth with bottled water, or tap water that has been boiled.
If you are travelling to an area where cholera is endemic, oral cholera vaccines which reduce the risk of getting cholera are available. Your doctor can give you more details.
WHO has issued the following advice for travellers:
By taking a few basic precautions when travelling, cholera as well as most other food and water-borne diseases can easily be prevented. The main rule is: Always be aware of the quality of what you eat and drink when you are travelling
- Drink only water that has been boiled or disinfected with chlorine, iodine or other suitable products. Products for disinfecting water are generally available in pharmacies. Beverages such as hot tea or coffee, wine, beer, carbonated water or soft drinks, and bottled or packaged fruit juices are also usually safe to drink
- Avoid ice, unless you are sure that it is made from safe water.
- Eat food that has been thoroughly cooked and is still hot when served. Cooked food that has been held at room temperature for several hours and served without being reheated can be an important source of infection.
- Avoid raw seafood and other raw foods, except fruits and vegetables that you have peeled or shelled yourself. Remember: Cook it, peel it, or leave it.
- Boil unpasteurised milk before drinking it.
- Ice cream from unreliable sources is frequently contaminated and can cause illness. If in doubt, avoid it.
- Be sure that meals bought from street vendors are thoroughly cooked in your presence and do not contain any uncooked foods.
If you are travelling with family members or others, ensure that they also take these precautions. Infants under six months who are breast-fed, and take no other foods or drinks, have a low risk of getting cholera.
What should I do if I or someone I know gets sick while travelling?
If you think you or a member of your group might have cholera, seek medical help straight away. Dehydration can happen very quickly. If you have oral rehydration solution, start drinking it straight away, it can stop you from getting very sick. Continue to drink oral rehydration solution at home and while travelling to get medical treatment. If a baby has watery diarrhoea, continue breast-feeding.
What happens if a case appears in Ireland?
Every so often, a person gets cholera outside of Ireland and returns home with it. This is an ‘imported’ case. Imported cases in Western European countries, including Ireland, are found quickly and actions are taken by Public Health professionals to stop other people getting cholera. These actions are called control measures.
Control measures for cholera are similar to those for other diarrhoeal illnesses. People who were very close to the person with cholera while they were ill (contacts) are checked to see if they also have cholera. Where the ill person or their contacts work in a job where they could spread cholera to lots of people (for example a chef/cook or a healthcare worker) they must remain away from work until there is no chance they will give cholera to other people. These control measures, as well as most people in Ireland having safe drinking water and good washing and toilet facilities, mean there is little danger cholera spreading in Ireland.
Where can I learn more about cholera?
The following are valuable resources for current information on cholera:
European Centre for Disease Prevention and Control
Centers of Disease Control and Prevention, US
Updated 30th November 2022