Cholera is a bacterial disease usually spread through contaminated water. Cholera causes severe diarrhea and dehydration. Left untreated, cholera can be fatal in a matter of hours, even in previously healthy people.
Modern sewage and water treatment have virtually eliminated cholera in industrialized countries. The last major outbreak in the United States occurred in 1911. But cholera is still present in Africa, Southeast Asia, Haiti and central Mexico. The risk of cholera epidemic is highest when poverty, war or natural disasters force people to live in crowded conditions without adequate sanitation.
Cholera is easily treated. Death results from severe dehydration that can be prevented with a simple and inexpensive rehydration solution.
Vibrio cholerae, the bacterium that causes cholera, is usually found in food or water contaminated by feces from a person with the infection. Common sources include:
- Municipal water supplies
- Ice made from municipal water
- Foods and drinks sold by street vendors
- Vegetables grown with water containing human wastes
- Raw or undercooked fish and seafood caught in waters polluted with sewage
When a person consumes the contaminated food or water, the bacteria release a toxin in the intestines that produces severe diarrhea.
It is not likely you will catch cholera just from casual contact with an infected person.
V cholerae is a comma-shaped, gram-negative aerobic or facultatively anaerobic bacillus that varies in size from 1-3 µm in length by 0.5-0.8 µm in diameter (see the image below). Its antigenic structure consists of a flagellar H antigen and a somatic O antigen. The differentiation of the latter allows for separation into pathogenic and nonpathogenic strains. Although more than 200 serogroups of V cholerae have been identified, V cholerae O1 and V cholerae O139 are the principal ones associated with epidemic cholera.
Most people exposed to the cholera bacterium (Vibrio cholerae) don’t become ill and never know they’ve been infected. Yet because they shed cholera bacteria in their stool for seven to 14 days, they can still infect others through contaminated water. Most symptomatic cases of cholera cause mild or moderate diarrhea that’s often hard to distinguish from diarrhea caused by other problems.
Only about 1 in 10 infected people develops the typical signs and symptoms of cholera, usually within a few days of infection.
Symptoms of cholera infection may include:
- Diarrhea. Cholera-related diarrhea comes on suddenly and may quickly cause dangerous fluid loss — as much as a quart (about 1 liter) an hour. Diarrhea due to cholera often has a pale, milky appearance that resembles water in which rice has been rinsed (rice-water stool).
- Nausea and vomiting. Occurring especially in the early stages of cholera, vomiting may persist for hours at a time.
- Dehydration. Dehydration can develop within hours after the onset of cholera symptoms. Depending on how many body fluids have been lost, dehydration can range from mild to severe. A loss of 10 percent or more of total body weight indicates severe dehydration.
Signs and symptoms of cholera dehydration include irritability, lethargy, sunken eyes, a dry mouth, extreme thirst, dry and shriveled skin that’s slow to bounce back when pinched into a fold, little or no urine output, low blood pressure, and an irregular heartbeat (arrhythmia).
Dehydration may lead to a rapid loss of minerals in your blood (electrolytes) that maintain the balance of fluids in your body. This is called an electrolyte imbalance.
An electrolyte imbalance can lead to serious signs and symptoms such as:
- Muscle cramps. These result from the rapid loss of salts such as sodium, chloride and potassium.
- Shock. This is one of the most serious complications of dehydration. It occurs when low blood volume causes a drop in blood pressure and a drop in the amount of oxygen in your body. If untreated, severe hypovolemic shock can cause death in a matter of minutes.
Signs And Symptoms Of Cholera In Children
In general, children with cholera have the same signs and symptoms adults do, but they are particularly susceptible to low blood sugar (hypoglycemia) due to fluid loss, which may cause:
- An altered state of consciousness
It is almost impossible to distinguish a single patient with cholera from a patient infected by another pathogen that causes acute watery diarrhea without testing a stool sample. A review of clinical features of multiple patients who are part of a suspected outbreak of acute watery diarrhea can be helpful in identifying cholera because of the rapid spread of the disease.
While management of patients with acute watery diarrhea is similar regardless of the illness, it is important to identify cholera because of the potential for a widespread outbreak.
Cholera requires immediate treatment because the disease can cause death within hours.
- Rehydration. The goal is to replace lost fluids and electrolytes using a simple rehydration solution, oral rehydration salts (ORS). The ORS solution is available as a powder that can be reconstituted in boiled or bottled water. Without rehydration, approximately half the people with cholera die. With treatment, the number of fatalities drops to less than 1 percent.
- Intravenous fluids. During a cholera epidemic, most people can be helped by oral rehydration alone, but severely dehydrated people may also need intravenous fluids.
- Antibiotics. While antibiotics are not a necessary part of cholera treatment, some of these drugs may reduce both the amount and duration of cholera-related diarrhea. A single dose of doxycycline (Monodox, Oracea, Vibramycin) or azithromycin (Zithromax, Zmax) may be effective.
- Zinc supplements. Research has shown that zinc may decrease and shorten the duration of diarrhea in children with cholera.