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Microbes

Author(s): Nancy Moreno, PhD, Barbara Tharp, MS, Deanne Erdmann, MS, Sonia Rahmati Clayton, PhD, and James Denk, MA.

Disease Information: Cholera

Are you familiar with the phrase, “Don’t drink the water”? It’s usually heard when someone is traveling, especially outside of the U.S. Our water treatment system is very good, so the water in our homes usually is healthy to drink. Also, laws in this country help to ensure that our food sources generally are safe. 

But this is not the case everywhere. When you visit some countries, you may be warned not to drink water from the faucet, not to drink beverages containing ice, and not to eat any food unless you have cooked or peeled it. There’s a good reason for these warnings. Sometimes, uncooked food and untreated water can make you sick!

Something in the Water and Food 
Every year, many people around the world get dangerous diseases from food and water that are not safely prepared or treated. One of these diseases is cholera, an infection of the intestines caused by the bacterium, Vibrio cholerae. We don’t have many cases of cholera in the U.S. In fact, it has been rare in much of the world for 100 years or more. Unfortunately, it still affects millions of people in Asia, Africa, and other places that suffer from poor hygiene, unsanitary conditions, and lack of money for proper medical care and medicine. 

Many people who get cholera do not feel ill. Some experience nothing more serious than a bad case of diarrhea. But about 10% of cholera victims suffer life-threatening symptoms, including continuous diarrhea, vomiting and leg cramps. These people lose body fluids so quickly that they become severely dehydrated, and even may go into shock. Without medication, they can die within hours.

Wash Your Hands, Please
Cholera is spread by contaminated (dirty or spoiled) water and food. Most often, contamination happens when human and/or animal waste (feces) gets into our water or food. It’s disgusting, but that’s the way it usually happens.

Vibrio cholerae bacteria infect the intestine and remain in the body for one to two weeks. If an infected person who is preparing food doesn’t wash his or her hands after using the bathroom, he or she might spread the bacteria to the food. Anyone who eats this food might get sick. Other kinds of intestinal diseases are spread in the same way. That’s why you often see signs in restaurant bathrooms, reminding employees to wash their hands before returning to work.

In places with poor sewage systems or improper water treatment, human waste can get into the water supply. In these places, many people can become sick with cholera. That’s how some outbreaks happen.

But cholera isn’t always caused by human waste. Vibrio cholerae bacteria can exist naturally in salty rivers and coastal waters, where shellfish (crabs, clams, oysters, etc.) live. If shellfish are boiled for less than 10 minutes, steamed for less than 30 minutes, left unrefrigerated for several hours, or eaten raw, they can cause cholera and other diseases. 

The Danger Today
Cholera outbreaks have occurred throughout the world for thousands of years. Stories from ancient Greece, and even earlier, report epidemics of cholera-like illnesses. The disease was common in the U.S. in the 1800s, but it no longer is a major concern, because we have modern water treatment, food preparation and sewage systems. 

Cholera is easy to prevent with good sanitation and water treatment. It can be cured by giving fluids along with antibiotics, if necessary. But some countries do not have the resources needed to fight a cholera outbreak, so this disease continues to present a very real threat to human life.

The most recent cholera pandemic (worldwide outbreak) began in Asia in 1961. It spread to Europe and Africa and, by 1991, to Latin America, where there had been no cholera for more than 100 years. This outbreak has killed thousands of people and continues to spread. Cholera can be a risk for anyone traveling to places where outbreaks are occurring.


Funded by the following grant(s)

Science Education Partnership Award, NIH

MicroMatters
Grant Number: 5R25RR018605