Cholera outbreak: symptoms, sources of infection and precautions that can be taken to avoid illness

Cholera is an acute diarrhoeal infection characterised, in its severe form, by extreme watery diarrhoea and potentially fatal dehydration.

It is a notifiable medical condition. 

Most cholera infections are asymptomatic or mild, indistinguishable from other mild diarrhoea and affect all age groups. Nausea and profuse vomiting may occur. 

It is caused by the ingestion of food or water contaminated with the bacterium Vibrio cholerae, which can survive in fresh and salt water. 

Cholera has a short incubation period, ranging between two hours and five days, according to the South African guidelines for cholera control published by the national health department and National Institute For Communicable Diseases (NICD).

Sources of infection: 

• Contaminated water or food are the main drivers of infection, but person-to-person transmission is another contributor. 
• Drinking water that has been contaminated at its source or during storage can result in infections. 
• Foods and vegetables exposed to fertiliser or water that contains  human excretions can also cause infections. 
• Beverages, ice and bottled water prepared with contaminated water. 
• Soiled hands can contaminate clean drinking water and food.
• Fish, particularly shellfish, taken from contaminated water and eaten raw or insufficiently cooked.
• Cholera is transmittable as long as the bacteria are secreted in stool. Both asymptomatic as well as symptomatic people secrete infective bacteria.

Prevention and control:

• Drinking and cooking with good quality water and good hygiene practices prevent cholera.
• The simplest and most cost-effective method is chlorination of water in a storage container using household bleach. Add one teaspoon (5ml, or one cap full if bottle has a screw cap) of household bleach to 20 to 25 litres of water and thoroughly mix solution with water and allow to stand for at least two hours or overnight. 
• In an outbreak situation boiling is also effective in prevention, but there is a potential for microbial regrowth if the boiled water is stored beyond one or two days.  
• Filtration may be necessary in addition to boiling water by using a piece of clean white cloth to cover the opening of a 20 or 25 litre water container. Pour water through the clean cloth into the container. Clean the cloth and make sure it is always clean for future use.
• Wash hands with soap and clean water before preparing and eating food, and after going to the toilet. Wash all surfaces and equipment used for food preparation with soap and clean water.  
• Cook food thoroughly. Avoid uncooked food, especially shellfish and meat. Eat food while it is still hot. Wash and peel all fruit and vegetables before eating, especially when eaten raw. 
• Do not use manure that contains faeces on vegetable gardens or crops.
• Seek medical care immediately when symptoms present and use an oral rehydration solution or correction fluid to avoid dehydration. 

Source: National guidelines for cholera control by the national department of health

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