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21 March 2017

Causative agent

Cholera is an acute diarrhoeal disease caused by the bacterium Vibrio cholerae. Toxigenic Vibrio cholerae serogroups O1 and O139 can cause epidemic cholera.

Clinical features

Most patients do not have symptoms or only have mild diarrhoea while some develop severe watery diarrhoea with rice-water like stool and vomiting. Without prompt treatment, these patients may die from severe dehydration.

Mode of transmission

Cholera is usually contracted through consumption of food or water contaminated with Vibrio cholerae. Human-to-human transmission rarely happens.

Incubation period

Ranges from a few hours to 5 days, usually 2 - 3 days


The mainstay of treatment is timely and adequate rehydration. For mild dehydration, patients may take oral rehydration solution. Severe dehydration cases usually require intravenous rehydration to replenish fluid and electrolyte loss. Antibiotics may also be used.


Preventive measures are based on good personal, food and environmental hygiene. 

1.  Personal hygiene

  • Wash hands thoroughly with liquid soap and water before handling food or eating, and after using toilet, or handling faecal matter.
  • Exclude infected persons and asymptomatic carriers from handling food and from providing care to children, elderly and immunocompromised people.
  • Refrain from work or school, and seek medical advice if suffering from gastrointestinal symptoms such as diarrhoea.

2.  Food hygiene

  • Adopt the 5 Keys to Food Safety in handling food, i.e. Choose (Choose safe raw materials); Clean (Keep hands and utensils clean); Separate (Separate raw and cooked food); Cook (Cook thoroughly); and Safe Temperature (Keep food at safe temperature) to prevent foodborne diseases.
  • Purchase fresh food from hygienic and reliable sources. Do not patronise illegal hawkers.
  • Wash and peel fruit by yourself and avoid eating raw vegetables.
  • Eat only thoroughly cooked food.
  • Drink only boiled water from the mains or bottled drinks from reliable sources. If water cannot be boiled, treat water with chlorine or iodine before consumption (Follow the instructions on the package carefully).
  • Avoid drinks with ice of unknown origin.

* Please visit the website of Centre for Food Safety for more information on food safety.

3.  Environmental hygiene

  • Maintain proper sanitary facilities and drainage system.
  • Cleanse and disinfect toilets used by infected person and the soiled areas.

Tips for travellers

Take the following precautions when travelling to cholera-affected areas:

  • Maintain good personal, food and environmental hygiene.
  • Travellers returning from affected areas should consult the doctor promptly if they have symptoms of cholera. Inform the doctor of your travel history and maintain good personal, food and environmental hygiene to help prevent the spread of the disease.
  • Oral cholera vaccine is rarely recommended except for those at high risk e.g. aid workers. It is not officially required as a condition of entry of any country. Please visit the website of Travel Health Service of the Department of Health for more details.
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