Shigella Infection: Symptoms, Spread and Prevention

Shigella are bacteria that cause diarrhea. The infection they cause is called shigellosis. In the United States, Shigella cause an estimated 450,000 infections each year, and infections resistant to antimicrobials run up an estimated $93 million in direct medical costs.

People most often get sick by eating or drinking contaminated food or water, or through contact with someone who is sick or was recently sick with Shigella. It can also spread during sex with a sick person.

Four species

Symptoms

Symptoms usually begin 1–2 days after infection and last 7 days. Most people have:

• diarrhea, which can be bloody or prolonged (more than 3 days);
• fever;
• stomach pain;
• a feeling of needing to pass stool even when the bowels are empty.

Who is at higher risk

• Children under 5 are the most likely to get shigellosis, though people of any age can. Many outbreaks happen in early care and education settings and schools.
• Travelers to places where food and water may be unsafe and sanitation is poor are more likely to be infected, and more likely to get types of Shigella that are harder to treat.
• Gay, bisexual and other men who have sex with men (GBMSM) face factors that raise their risk. Rates are higher in this group, but any sexual activity that involves exposure to stool carries the risk.
• People experiencing homelessness are at high risk when shigellosis is spreading in the community. Their living situations can make transmission, and outbreaks, more likely.

How it spreads

Shigella spreads easily: swallowing only a small amount of the germs can cause illness. The germs are in poop, so anything contaminated with poop can spread them. That includes other people, and contaminated water, food, surfaces and objects.

Prevention

• Wash hands with soap and water at key times.
• Take care when changing diapers.
• Avoid swallowing water while swimming.
• When traveling abroad, follow safe food and water habits and clean your hands often.
• If you or a partner has been diagnosed with shigellosis, don't have sex for at least two weeks after the diarrhea ends.

Treatment and recovery

Most people with shigellosis get better without antibiotics in 5 to 7 days, and mild cases may need only fluids and rest. A health care provider may prescribe medicine to treat the illness. Anyone with diarrhea should drink plenty of water or other fluids to avoid dehydration.

Sources

• CDC, "About Shigella Infection" (January 10, 2024): https://www.cdc.gov/shigella/about/index.html
• CDC, "Preventing Shigella Infection": https://www.cdc.gov/shigella/prevention/index.html