Is Cholera Contagious?

Infection with the bacteria Vibrio cholera causes cholera.

Cholera is an infectious disease caused by bacteria named Vibrio cholerae. Cholera causes profuse diarrhea episodes and vomiting. The cause of cholera are toxins secreted by the Vibrio cholerae bacteria. Microscopically, these bacteria appear curved (comma-shaped) and have a negative Gram stain. Cholera causes severe loss of fluid and electrolytes from the body due to vomiting and profuse diarrhea. Less frequently, some people infected have few or no symptoms. If fluids and electrolytes are not restored to the individual, more severe symptoms, including dehydration and shock, may occur quickly (about 12-48 hours). Death occurs in about 15%-20% of patients who develop severe symptoms and signs.

Cholera is highly contagious. Cholera can be transferred person to person by infected fecal matter entering a mouth or by water or food contaminated with Vibrio cholerae bacteria. The organisms can survive well in salty waters and can contaminate humans and other organisms that contact or swim in the water.

The time period from exposure to the bacteria until the development of symptoms (incubation period) is relatively short for cholera, varying from about 12 hours to five days. Most people develop symptoms of watery diarrhea (termed "rice-water stools") with frequent stooling. More severe symptoms include frequent vomiting, rapid heart rate, dry mucous membranes, muscle cramps, restlessness, thirst, loss of skin elasticity, and low blood pressure. As symptoms progress, some patients can develop kidney failure and/or hypovolemic shock. Detection of cholera is simple with testing of stool samples with a special dipstick. Examination of the watery diarrhea for characteristic Vibrio bacteria (comma-shaped bacteria) by microscopy can be helpful. Subsequent culture of the organisms from stool samples will confirm preliminary dipstick and microscopic identification.

Cholera is spread many ways. Cholera bacteria can survive in areas outside the body and can easily contaminate water sources and food. In addition, individuals with the disease produce large numbers of Vibrio bacteria in their stools that can contaminate other people, as well as clothing, sheets, and many other items in the home. The usual spread of Vibrio cholerae bacteria is by infected fecal matter entering the mouth.

A person is no longer contagious for cholera when they have no cholera symptoms and no detectable Vibrio bacteria in their stools. Cholera, in general, usually lasts about one week, unless severe symptoms develop. Although a person may be no longer contagious for cholera, the infection does not provide enough immunity to prevent the person from coming down with cholera again if reexposed to the bacteria.

Anyone who thinks they might have been exposed to cholera, especially if they have early symptoms of the disease, should seek medical care emergently. Do not wait until symptoms become more severe. The earlier fluids and electrolytes are replenished, the more likely the individual will not develop severe symptoms, have a prolonged hospital stay, or die.