Reviewed August 2017

What Is Shigellosis?

Shigellosis is a bacterial infection of the intestines caused by the Shigella bacterium. People are the only source for Shigella bacteria. Shigellosis is easily transmitted from one person to another since ingesting just 10 bacteria is enough to cause illness.

What Are the Symptoms of Shigellosis?

Most people who are infected with Shigella develop diarrhea, fever, and stomach cramps. Diarrhea may be mild to severe and may have traces of blood or mucous. Some infected people may not show any symptoms but may still pass the Shigella bacterium to others. In some persons, especially young children and the elderly, diarrhea can be severe enough to require hospitalization. Shigellosis can cause severe infection with high fever and seizures in children less than 2 years old.

Who Can Get Shigellosis?

Anyone can get shigellosis but symptoms are more common in young children. Those who may be at greater risk of becoming infected include children in daycare centers, travelers to certain countries and men who have sex with men. Family members and playmates of infected children are at increased risk of becoming infected because young children often do not wash their hands adequately after using the toilet.

How Is the Shigella Bacterium Spread?

Shigella is found in the intestine of infected people and is passed in their stool. It is spread by eating or drinking food or water contaminated by an infected person’s stool or by direct contact with that person’s contaminated hands. Shigella is present in the stool of an infected person while they have symptoms and for a week or two afterwards.

How Soon After Becoming Infected Do Symptoms Appear?

The symptoms may appear one to seven days after a person becomes infected but it is usually within two to three days. People usually feel better in five to seven days.

When Can an Infected Person Spread Shigellosis?

Most infected people pass Shigella in their stool for one to two weeks after symptoms start. Antibiotics may shorten the time that a person can spread the bacterium to others.

How Is Shigellosis Treated?

Most people with shigellosis will recover on their own. Some may require intravenous fluids to prevent dehydration. Antibiotics are occasionally used to treat severe cases or to eliminate bacteria from a person’s stool. This is particularly important for food handlers, children in daycare or institutionalized individuals.

What Can Be Done to Prevent the Spread of Shigellosis?

Thorough hand washing is the best prevention. Since bacteria are passed in stool, the single most important prevention activity is careful hand washing after using the toilet, before preparing food and before eating.

Drink water from a safe supply. When traveling, use bottled water or boil the water for at least five minutes if the water supply is unknown. Remember that ice cubes can also be contaminated. Avoid swimming in water that may be contaminated.

Avoid eating raw shellfish harvested from unknown sources. Protect food against flies and cockroaches as they can carry the Shigella bacterium. Wash all fruits and vegetables before use.

Are there any restrictions for people with shigellosis?

Persons with shigellosis should stay home until at least 24 hours after their symptoms have resolved. Food handlers, those who provide healthcare services and those who work or attend a child care centre should stay home until they are no longer infected with Shigella. Toronto Public Health will inform you when you can return to work after you have been tested.

More Information

Call Toronto Public Health at 416-338-7600 (TTY at 416-392-0658) or speak to your health care provider.