Cholera is an acute intestinal infection caused by Vibrio cholerae, a facultative anaerobic, Gram-negative, crescent-shaped, motile rod. In severe cases it produces violent diarrhoea within only a few days. The dangerous aspect of cholera is the vast loss of fluid that can occur in a short space of time.
Cholera is caused by a specific bacterium, Vibrio cholerae. When an adequate quantity of the bacteria has passed into the stomach in food they accumulate and begin to produce poisonous substances (toxins). It is the toxin that causes the symptoms of the disease.
The cholera toxin has the unpleasant ability to affect the cells of the gastrointestinal tract so that the affected person doesn't just get ordinary diarrhea, but also starts to lose very large quantities of fluid. It is this fluid loss that can be very serious.
- Sudden onset of watery diarrhea
- Stool looks like water with flecks of rice
- Diarrhea has a "fishy" odor
- Rapid dehydration
- Rapid pulse (heart rate)
- Dry skin
- Dry mucous membranes or dry mouth
- Excessive thirst
- Glassy eyes or sunken eyes
- Lack of tears
- Unusual sleepiness or tiredness
- Low urine output
- Sunken "soft spots" (fontanelles) in infants
- Abdominal cramps
Bacteria are excreted in faeces and if this comes into contact with drinking water, the bacteria can infect people. Bacteria can also spread to food if people don't wash their hands thoroughly after using the toilet.
The disease can be spread through fish and shellfish from contaminated water. Shellfish filter large quantities of water and concentrate the bacteria.
Direct infection by contact with another person via their faeces or vomit may occur, but is unusual. A certain amount of bacteria is needed before people with normal quantities of stomach acid become ill (stomach acid is able to kill small quantities of bacteria). So the bacteria need an opportunity to multiply in water or food before it actually constitutes a risk.
Many diseases cause diarrhoea, but if it is violent with watery stools, the doctor will treat you immediately. To make a definite diagnosis, the stools have to be examined to detect the cholera bacteria.
Severe cases of the disease must be treated in hospital. The first and most vital measure is to replace the fluid lost. If speed is important, fluid may be administered directly into the bloodstream by a drip.
The course of the disease can be shortened and the excretion of bacteria stopped quicker by giving antibiotics, such as doxycycline (eg Vibramycin).
The most important thing you can do yourself in any case of violent diarrhoea is to consume large quantities of fluid with salt and sugar (alternatives include flat cola drinks), even if you are vomiting in between. There are powders with salt, bicarbonate and sugar in the correct ratio mixture that can be dissolved in water and taken, such as Dioralyte, WHO Rehydration satchets or Rehidrat.
You can also produce this fluid yourself from the following ingredients. The liquid should be about as salty as tears.
- 1 litre of boiled water.
- 8 level or 4 heaped teaspoons of sugar (white, brown or honey).
- 1/2 teaspoon of salt.
- The juice of a lemon or orange.
Only drink boiled water or water that has been sterilised or treated in another way. Hot coffee and tea, fizzy water and other uncontaminated bottled drinks are usually safe enough to drink.
Boil unpasteurised milk before you drink it.
Avoid ice cubes in drinks, unless you can be sure they were made from 'safe water'! Ice cream from doubtful sources may also be contaminated.
Food must be properly prepared and still hot when it is served. If it is allowed to stand at room temperature for several hours other bacteria such as Escherichia coli may develop.
Avoid raw fish and shellfish. Avoid raw fruit and vegetables, unless you peel it yourself.
Be careful eating food from street stalls. If you have to eat this type of food, think carefully about its preparation. Make sure it doesn't contain anything that hasn't been properly prepared.
This advice will protect you, not just against cholera, but also against a whole range of bacteria that can cause unpleasant diarrhoea. Some bacteria, however, produce toxins that are not destroyed by boiling. This is why correct food storage is also important.
Vaccination against cholera is now possible with the oral vaccine Dukoral. However, this vaccine does not provide 100 per cent protection against the disease and people who have had the vaccine will still need to follow the measures outlined above to avoid illness. This vaccine is most likely to be suitable for backpackers and those travelling to situations where the risk of cholera is greatest (eg, refugee camps).