WHO advice for international travel and trade in relation to cholera
21 September 2018
Cholera is an acute infection caused by the ingestion of water or food contaminated with bacterium Vibrio cholerae. Cholera affects only humans; there is no insect vector or animal reservoir host. It is closely linked to inadequate access to clean water and sanitation facilities. Most people infected with V. Cholerae do not develop symptoms, or have mild diarrhoea. The bacteria are present in the faeces for 1-10 days after infection and are shed back into the environment, potentially infecting other people. Severe cases develop profuse watery diarrhea. Cholera is an easily treatable disease. The majority of patients can be treated successfully through prompt administration of oral rehydration solution.
The number of cholera cases reported to WHO has continued to be high over the last few years. During 2016, 132 121 cases were notified from 38 countries, including 2420 deaths. In 2017, 34 countries reported a total of 1 227 391 cases (84% of which in Yemen) and 5654 deaths. In 2018 several countries reported cholera outbreaks. However, many cases are not recorded due to limitations in surveillance systems and fear of potential impact on trade and tourism.
Risk of infection for international travellers
The risk of infection for international travellers is very low for most travellers, even in countries where cholera outbreaks are active, as long as they follow appropriate preventive measures (see below). Humanitarian relief workers may be at risk if they are likely to be directly exposed to cholera patients or to contaminated food or water, particularly those staying in areas with poor access to health care facilities.
Travel-related recommendations to prevent the international spread of cholera
Travellers to countries reporting cholera outbreaks should seek travel advice before the journey and should receive information on risks of cholera infection, cholera symptoms, measures to avoid risk of exposure, and when and where to report for care should cholera symptoms develop.
To minimize the risk of infection, travellers in the affected areas should:
- Practice regular hygiene, especially hand hygiene with soap and water, and if not available with an alcohol-based hand rub solution (hand sanitizer);
- Practice hand hygiene especially before touching eyes, nose or mouth, and after using the toilet or touching objects at high risk of being contaminated;
- All precautions should be taken to avoid consumption of potentially contaminated food, drink and drinking-water by consuming food and water only from known safe sources.
- Follow the five keys for safe food: wash hands often and always before handling and consuming food, make sure the food is cooked thoroughly, peel all fruits and vegetables if eaten raw, drink bottled water if available, or if the source of water is doubtful, bring it to a vigorous boil, separate cooked food from raw food, avoid uncooked food, and keep food at safe temperatures.
Chemoprophylaxis for travellers going to or coming from cholera-affected areas has not demonstrated to have any effect on the spread of cholera, but can have adverse effects by increasing antimicrobial resistance, and provides a false sense of security. Therefore, WHO does not advise requiring prophylactic administration of antibiotics or proof of such administration for travellers coming from or going to a country affected by cholera.
Oral cholera vaccines (OCV) are only to be considered for travellers at high risk (emergency/ relief workers), who are likely to be directly exposed to cholera patients or contaminated food or water, particularly those staying in areas with poor access to health care facilities.
Travellers should be informed about where to obtain appropriate medical assistance at their destination and whom to inform should they become ill. Oral rehydration salts(ORS) should be carried to combat dehydration in case of severe diarrhea.
There is a possibility that a person who has been exposed to cholera and developed symptoms may board a commercial flight or other mode of transport, without informing the transport company of his/her status. Such travellers should inform the crew about their symptoms and recent travel history, so that necessary arrangements can be made for medical assistance upon arrival, and further transmission can be prevented.
Measures at points of entry (airports, seaports and ground-crossings)
Routine screening or restrictions on movements of people, including quarantine measures or "cordon sanitaire", have never been shown to be effective in the control of cholera, and are therefore viewed as unnecessary. WHO advises against the application of routine screening, or any other restrictions on movements, such as quarantine of travellers coming from areas experiencing an outbreak of cholera.
Any health measure on arrival or departure, or relating to entry of travelers, should be applied in compliance with the provisions of the International Health Regulations (2005).
The airlines and shipping lines should be advised by Points of Entry health authorities of the risks and disease symptoms to facilitate the identification of suspected cases on board conveyance. Points of Entry should determine if their water systems are safe from contamination and enhance monitoring. Airlines and shipping lines should only take on food and potable water from affected countries if the source has been deemed safe.
Ships should not bunker water for production of potable water from contaminated water sources, such as harbours, gulfs and rivers. The ships calling at the ports of the affected area should review the water safety plans on board, in the case of absence of water safety plan, it should be developed by shipping lines to ensure particular risks are addressed.
Trade-related recommendations to prevent the international spread of cholera
WHO does not advise implementation of embargoes or similar restrictions on trade related to countries affected by cholera outbreaks. Food produced under good manufacturing practices poses no risk for cholera transmission. There is no evidence that commercially traded food has resulted in cholera outbreaks in importing countries, neither proof that trade restriction to countries affected by cholera is effective in preventing the spread of the disease.
Recommendations for countries neighbouring an area affected by cholera
Countries neighbouring an area affected by cholera are advised to implement the following measures:
- Improve national preparedness to rapidly respond to an outbreak and limit its consequences, should cholera spread across borders;
- Improve disease surveillance to obtain better data for risk assessment and early detection of cases, including establishing an active surveillance system;
- Provide information to travellers on risks of cholera, precautions to avoid infection, cholera symptoms, and when and where to report should these symptoms develop.