Shigella Infection: Symptoms, Causes, Prevention, and Treatment

Shigella infection, also called shigellosis, is an intestinal disease caused by a family of bacteria known as shigella. The main sign of shigella infection is diarrhea, which often is bloody in appearance.

Shigella can be passed on through direct contact with the bacteria in the stool, like in a child care setting when staff members don’t wash their hands well enough after changing diapers. Shigella bacteria also can be transmitted via a contaminated food or by drinking or swimming in contaminated water.

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Those most likely to get shigella infection are children between the ages of 2 and 4. A mild case can resolve on its own within a week. Doctors normally prescribe antibiotics for cases that require treatment.

Symptoms of Shigella infection

Symptoms of shigella infection usually start a day or two after exposure to shigella, however, it may take up to a week for symptoms to become obvious. Signs and symptoms may include:

Although some people show no symptoms after they’ve been infected with shigella, their feces may still be contagious up to a few weeks.

When to see a doctor

If you or your child has bloody diarrhea or diarrhea severe enough to cause weight loss and dehydration, consult your doctor. Also, contact your doctor if you or your child has diarrhea and a fever of 101 F (38 C) or higher.

Causes of Shigella infection

Infection occurs when shigella bacteria is accidentally swallowed either by:

  • Touching your mouth.If you don’t wash your hands well after changing the diaper of a child who has shigella infection, you may become infected yourself. Direct person-to-person contact is the most common way the disease is spread.
  • Eating contaminated food.Infected people who handle food can transmit the bacteria to people who eat the food. Food can also become contaminated if it grows in a field that contains sewage.
  • Swallowing contaminated water.Water, especially in swimming pools, may become contaminated either from sewage or from a person with shigella infection swimming in it.

Risk factors

  • Being a toddler.Shigella infection is most common in children between the ages of 2 and 4.
  • Living in group housing or participating in group activities.Close contact with other people spreads the bacteria from person to person. Shigella outbreaks are more common in child care centers, nursing homes, community wading pools, jails and military barracks.
  • Living or traveling in areas that lack sanitation.People who live in or travel to developing countries are more prone to contract shigella infection.
  • Being a sexually active gay.Men who have sex with men are at higher risk because of direct or indirect oral-anal contact.


Shigella infection usually clears up without complications, although it may take weeks or months before your bowel habits return to normal.

Complications may include:

  • Constant diarrhea can cause dehydration. Symptoms include dizziness, sunken eyes and dry diapers. Severe dehydration can lead to shock and death.
  • Some children who run high fevers with a shigella infection have seizures. Contact your doctor immediately if your child has a seizure.
  • Rectal prolapse.Straining during bowel movements may cause the mucous membrane or lining of the rectum to shift outwards through the anus.
  • Hemolytic uremic syndrome.This rare complication of shigella, caused by bacteria called E. coli, can lead to a low red blood cell count, low platelet count, and acute kidney failure.
  • Toxic megacolon.This rare complication occurs when your colon becomes paralyzed, preventing you from having a bowel movement or passing gas. Signs include abdominal pain and swelling, fever, and weakness. If you don’t receive treatment for toxic megacolon, your colon may rupture, causing peritonitis, which is a deadly infection requiring emergency surgery.
  • Reactive arthritis.Reactive arthritis develops in response to infection. Signs and symptoms include joint pain and inflammation, usually in the ankles, knees, feet and hips; redness, itching and discharge in one or both eyes (conjunctivitis); and painful urination or urethritis.


There is no vaccine yet for shigella. The World Health Organization has been working on a shigella vaccine. To prevent the spread of shigella:

  • Wash hands frequently and thoroughly
  • Encourage small children when they wash their hands after playing outside
  • Dispose of soiled diapers properly
  • Avoid sexual activity with anyone who has diarrhea
  • Disinfect diaper-changing areas after use
  • Avoid preparing food for others if you have diarrhea
  • Keep children with diarrhea home from child care, play groups or school
  • Avoid swallowing water from ponds, lakes or untreated pools


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