What is it?
Cholera is an infection of the small intestine by a certain type of bacteria. The typical symptoms are diarrhea and vomiting. An untreated sufferer might produce 10-20 liters of diarrhea in a day. This can easily result in life-threatening dehydration, which isn’t surprising given the fact that the amount of lost fluid is ten times more than what the average person drinks in a day. Without treatment cholera kills over half of its sufferers. If it is, however, treated quickly, the mortality rate falls to 1%.
Cholera affects about 3-5 million people worldwide, and causes about 58 000-130 000 deaths a year. It is most common in developing countries.
What causes it?
Cholera happens when the cholera bacterium gets ingested. This can happen if a healthy person eats or drinks food or water that has been contaminated by the feces of someone affected. In developed countries this most often happens through food – someone might, for example, eat seafood collected from a place where sewage water is also dumped nearby. In the developing world it is common that the diarrhea of a sufferer ends up in the water supply, and others get sick after drinking the contaminated water. About 100 000 000 bacteria have to be ingested to get ill.
What happens during it?
The stomach is very acidic and the vast majority of bacteria die there. If there are enough of them, however, some might get through to the small intestine. Here the cholera bacteria work their way through the protecting mucus layer and attach to the intestine wall. Once they have done this, their metabolic functions change and they start to produce the diarrhea-causing toxins.
The toxins get inside the cells lining the small intestine. There they bind to a certain molecule, which eventually leads to water and ions being secreted to the intestine. In addition to the dehydration, it is also very dangerous if there is a wrong concentration of the important ions like potassium. Signals travel along nerve cells because of the movement of ions and their electrical charges across the membrane. The heart, for example, relies on nervous signals when it contracts, and wrong ion concentrations can lethally alter this intricate balance.
How can it be treated?
Good sanitation is the most important factor in preventing cholera. Thanks to improved practices, cholera isn’t nearly as bad a health problem globally as it used to be. There are quite effective vaccines for cholera, too – vaccines work by introducing the microbe to the body in a safe environment so that it can develop a defense strategy in case of a more serious attack.
When ill, it is very important to continue eating. Since dehydration is the most serious complication of cholera, hydrating the sufferer through giving them lots of rice-based solution. This can normally be given orally, although in severe cases it might be necessary to give it straight in the vein. The concentration of potassium can decrease to dangerously low levels if the patient is gaining lots of fluid quickly, which is why it often has to be administered. Antibiotics might also be useful.