Cholera
In this condition factsheet:
The Facts on Cholera
Cholera is a bacterial infection of the small bowel that can cause severe diarrhea and dehydration.
There have been seven great pandemics (worldwide epidemics) of cholera in history. The seventh began in 1961, when cholera re-emerged in Indonesia and swept across most of the world, and it still lingers today.
Researchers estimate that each year there are 3 million cases of cholera worldwide, with approximately 100,000 deaths annually.
Cholera settles wherever poor hygiene permits it to infect humans, who appear to be cholera's only hosts. The bacterium that causes cholera is most productive in times of flood and war, since these events can reduce the availability of clean water. Cholera continues to occur in Asia, Africa, the Middle East, and South and Central America. Fewer than 1% of people with severe cholera die if they're quickly and properly treated.
Causes of Cholera
Cholera is caused by a bacterium called Vibrio cholerae. A person gets cholera by drinking water or eating food infected with the bacterium. Once swallowed, it settles in the lining of the small bowel and releases a toxin (poison) that can cause the body to flush liquid into the small bowel, resulting in watery diarrhea.
The bacterium that causes cholera is usually transmitted by water contaminated with human feces, but it can also be transmitted by ingesting contaminated food, especially raw or undercooked seafood and shellfish. Most people infected with cholera have no symptoms, yet they carry the bacteria for a few weeks, excreting them slowly into the water supply.
Naturally, this isn't a major problem in countries with flush toilets and sewage plants. Canada, the US, and Western Europe rarely report cholera, and if they do, it's almost always seen in someone who has returned from a high-risk country.
Symptoms and Complications of Cholera
Approximately 25% of people who ingest the bacteria actually develop the particular symptoms that we call cholera. Of those, 80% will experience symptoms that are only of mild or moderate severity, while up to 20% will develop severe watery diarrhea that can be life-threatening if not treated properly. The remainder will have no symptoms whatsoever, although they often excrete the bacteria in their stool, which can spread it to others.
It is not known why some people develop cholera while others are unaffected by the bacterial toxin. Most adults in cholera-endemic areas have some antibodies, which helps to protect them from developing the disease. In these countries, severe symptoms are far more common in children and in those who have some additional underlying disease such as AIDS.
Vibrio bacteria are killed by stomach acid. Research has shown that people with low acidity in their stomach (e.g., people taking antacid medications) are much more prone to cholera. Also, people with type O blood seem to be more at risk.
If symptoms of cholera occur, the main symptom is watery diarrhea, which can be severe enough to rapidly drain the body of vital water, salts, and minerals. The first watery stool appears 1 to 3 days after infection, and from then on the body can lose up to one litre of liquid an hour. Vomiting may appear at the same time.
Other symptoms of severe cholera are:
- muscle cramps
- reduced or no urination
- weakness
- low pulse
- sunken-looking eyes
- wrinkled skin on fingers
Cholera usually runs its course in 3 to 6 days, but if it is not treated it can cause shock from dehydration, kidney failure, coma, and death.
