Shigellosis - Epidemiology

What is shigellosis?

Shigellosis is an infection of the intestines caused by a bacterium called Shigella. It is very easy to spread to other people and thus sometimes results in outbreaks.

Who gets shigellosis?

Anyone can get shigellosis, but it is most common in young children. Those at greater risk for infection include children in child care centers and persons living in institutions. Outbreaks are most often associated with poor hygiene, crowded living conditions, and contaminated food or water. Travelers to developing countries and men who have sex with men are at increased risk of exposure.

How is shigellosis spread?

The bacteria have to enter the mouth to cause infection. People infected with Shigella shed the bacteria in their feces (stool). The feces can then contaminate surfaces, food, or water. People can become infected by touching contaminated surfaces, getting the bacteria on their hands and then putting their hands in their mouths, or by eating contaminated food or drinking contaminated water (including recreational water while swimming). Infected people should avoid swimming until after they no longer have diarrhea, and children should be discouraged from swallowing pool water. Infected food handlers can contaminate food if they do not wash their hands properly after going to the bathroom and handle food that other people eat. Hands contaminated while changing diapers can also spread the disease (e.g., in child care settings). Having exposure to stool during sexual contact with someone who is sick or recently recovered from shigellosis can spread the disease.

What are the symptoms of shigellosis?

People with shigellosis may experience mild or severe diarrhea (loose stools), often with fever and traces of blood or mucus in the stool. Some infected persons will also experience nausea and vomiting, while others may not show any symptoms at all.

How soon after exposure do symptoms appear?

Symptoms may appear anywhere from one to seven days after exposure, but usually appear within one to three days after exposure.

How is shigellosis diagnosed?

Shigellosis is diagnosed by performing laboratory testing on feces. The laboratory can also do special tests to determine which antibiotics, if any, would be best for treating the infection.

What is the treatment for shigellosis?

Most people with shigellosis will recover without treatment. Persons with diarrhea should drink plenty of fluids. In more serious cases, fluids might be given intravenously. Antibiotics are occasionally used to treat severe cases or to shorten the time the bacteria are present in the stool, particularly for food handlers, children in child care, or institutionalized individuals.

How can shigellosis be prevented?

Since Shigella is passed in feces, the single most important way to prevent its spread is careful hand washing with soap and warm water after using the toilet or changing diapers, and before and after preparing food. Avoiding contaminated food and water is also important. Avoid swallowing pool water, and stay out of the water while having diarrhea. Avoid having sex for one week after your partner recovers from diarrhea.

How long can an infected person carry Shigella bacteria?

Most people pass Shigella in their feces for one to two weeks. Certain antibiotics might shorten the time Shigella is present in an infected person’s feces.

Should an infected person be excluded from work or school?

Most infected people may return to work or school when their diarrhea stops. Food handlers, child care staff or attendees, and health care workers usually cannot return to work until two stool specimens are obtained and do not grow Shigella bacteria. The health department will help determine when people in these settings may return to work.

How can I learn more about shigellosis?

If you have concerns about shigellosis, contact your healthcare provider.
Call your local health department. A directory of local health departments is located at the VDH Local Health Districts page.
Visit the Centers for Disease Control and Prevention website at the CDC page on Shigella.