Cholera is an acute epidemic infectious disease. It is characterized by watery diarrhea, extreme loss of fluid and electrolytes, and severe dehydration. It can be fatal.
It is caused by the bacterium Vibrio cholera (V. cholera).
Despite being easy to treat, cholera is estimated to affect between 3 and 5 million people each year, and it causes over 100,000 deaths worldwide.
Due to severe dehydration, fatality rates are high when untreated, especially among children and infants. Death can occur in otherwise healthy adults within hours. Those who recover usually have long-term immunity against re-infection.
Cholera was prevalent in the United States in the 1800s, but now it is rare because there are well-developed sanitary systems and living conditions.
When traveling to Asia, Africa and some parts of Latin America, however, people need to protect themselves against cholera by having the appropriate vaccinations beforehand, drinking only water that is boiled or from a sealed bottle and following good handwashing practices.
What is cholera?
Diarrhea is the key symptom of cholera.
The cause of cholera is infection by the V. cholera bacteria. These bacteria were discovered in 1883.
The German bacteriologist, Robert Koch (1843-1910), studied the disease during an epidemic in Egypt. He found a bacterium in the intestines of those who had died of cholera but could neither isolate the organism nor infect animals with it.
Later that year, Koch went to India, where he succeeded in isolating the bacteria. He discovered that they thrived in damp, dirty linen and moist earth, and in the stools of patients with the disease.
V. cholera bacteria live in shallow, salty water on microscopic crustaceans. They can also exist as colonies of biofilms that coat the surface of the water, plants, stones, shells, and similar items, and they can live among the eggs of midges, which serve as a reservoir for cholera bacteria.
Toxic strains of cholera bacteria produce a poison that triggers violent diarrhea in humans.
When the bacteria enter areas where humans live, they can quickly cause severe epidemics. Weather changes, population loss, and improved sanitation can all end an outbreak.
Only around 1 in 20 cholera infections are severe, and a high percentage of infected people show no symptoms.
If symptoms appear, they will do so between 12 hours and 5 days after exposure. They range from mild or asymptomatic to severe.
They typically include:
large volumes of explosive watery diarrhea, sometimes called “rice water stools” because it can look like water that has been used to wash rice
A person with cholera can quickly lose fluids, up to 20 liters a day, so severe dehydration and shock can occur.
Signs of dehydration include:
decreased secretion, for example, less sweating
fast heart beat
low blood pressure
dizziness or lightheadedness
rapid weight loss
Shock can lead to collapse of the circulatory system. It is a life-threatening condition and a medical emergency.
Cholera is more common where there is overcrowding and poor sanitation.
Cholera bacteria enter the body through the mouth, often in food or water that has been contaminated with human waste, due to poor sanitation and hygiene.
They can also enter by eating seafood that is raw or not completely cooked, in particular shellfish native to estuary environments, such as oysters or crabs.
Poorly cleaned vegetables irrigated by contaminated water sources are another common source of infection.