Overview

Shigella infection is an illness that affects the intestine. Another name for it is shigellosis. It's caused by a group of germs called shigella bacteria.

Children under age 5 are most likely to get shigella infection. But the illness can happen at any age. The germs that cause it spread easily through an infected person's stool. The germs can get on fingers, on surfaces, or into food or water. Infection happens after the germs are swallowed.

The main symptom of shigella infection is diarrhea that can be bloody or long lasting. Other symptoms can include fever and stomach pain.

Most often, shigella infection clears up on its own within a week. Treatment for serious illness may include medicines called antibiotics that get rid of the germs.

Help prevent shigella infection by washing hands often, especially after changing a diaper or using the bathroom. And if you swim in ponds, lakes or swimming pools, try not to swallow the water.

Symptoms

Symptoms of shigella infection usually start a day or two after contact with the germs that cause it. Sometimes, the illness takes up to a week to start.

Symptoms can include:

  • Diarrhea that may contain blood or mucus, and that may last more than three days.
  • Stomach pain or cramps.
  • A feeling of needing to pass stool even when the bowel is empty.
  • Fever.
  • Upset stomach or vomiting.

Symptoms tend to last up to seven days. Sometimes they last longer. Some people have no symptoms after they've been infected with shigella. But the germs may be able to spread through the stool for up to a few weeks.

When to see a doctor

Call your healthcare professional or seek urgent care if you or your child has:

  • Bloody diarrhea.
  • Diarrhea that causes weight loss and dehydration.
  • Diarrhea along with a fever of 102 degrees Fahrenheit (39 degrees Celsius) or higher.
  • Terrible stomach cramps or tenderness.
  • Frequent vomiting that prevents you from keeping down liquids.
  • Dehydration symptoms such as little or no urination, very dry mouth and throat, or a feeling of dizziness when standing.

If you have a weakened immune system, call your healthcare professional if you have any shigella infection symptoms. The illness is more likely to make you sick for a longer time.

Causes

Shigella infection is caused by swallowing shigella bacteria. This can happen when you:

  • Touch your mouth. This poses a risk because there are many ways for shigella germs to get on your hands. You might change the diaper of a child who has shigella infection. Or you might touch an object that has germs on it, such as a toy or changing table. The germs also can spread from hand to mouth during sexual contact with someone who has the infection.
  • Eat tainted food. A person with a shigella infection who handles food can spread the germs to people who eat the food. Food also can become tainted if it grows in a field that contains sewage.
  • Swallow tainted water. Water can become tainted with shigella germs from sewage. Water also can become tainted if a person with shigella infection swims in it.

Risk factors

Risk factors for shigella infection include the following:

  • Being a child. Children under age 5 are most likely to get shigella infection. But people of any age can get the illness.
  • Living in group housing or doing group activities. Close contact with other people can spread the germs from person to person. Shigella outbreaks are more common in child care centers, schools, public pools, water parks and nursing homes.
  • Living or traveling in areas that lack clean water and sewage disposal services. People who live or travel in developing countries are more likely to get shigella infection.
  • Sexual contact that involves the anus. Shigella germs can spread from the stool or soiled fingers of one partner to the mouth of another partner. This puts men who have sex with men at higher risk of shigella infection.
  • Experiencing homelessness. This may involve staying in crowded areas or having less access to clean water and toilets. That can raise the risk of infection when shigella germs are spread through the community.
  • Having a weakened immune system. This raises the risk of more-serious shigella infection. The immune system may be weakened from health conditions such as HIV or from treatments such as chemotherapy.

Complications

It may take weeks or months before you return to your typical bowel habits. And most often, shigella infection clears up without leading to other health conditions called complications.

Dehydration

Constant diarrhea can cause dehydration. Symptoms include dizziness, lack of tears in children, sunken eyes and dry diapers. Serious dehydration can lead to shock and death.

Seizures

Some children with shigella infections have seizures. Seizures can cause changes in behavior, jerking movements and loss of consciousness. They are more common in children who have high fevers. But they also can happen in children who do not have high fevers.

It's not known whether the seizures are a result of the fever or the shigella infection itself. If your child appears to have a seizure, call your healthcare professional right away.

Rectal prolapse

This condition happens when part of the large intestine's lowest section slips outside the anus. It may be more common in children with shigella who don't get enough nutrition.

Hemolytic uremic syndrome

This rare complication of shigella affects the blood and blood vessels. It can lead to kidney failure.

Toxic megacolon

This rare complication prevents the colon from passing stool and gas. The colon becomes bigger as a result. Symptoms include stomach pain and swelling, fever, and weakness. Without treatment, the colon may burst. This causes a life-threatening infection called peritonitis that needs emergency surgery.

Reactive arthritis

This condition can happen weeks after shigella infection. Symptoms include joint pain and swelling, usually in the ankles, knees, feet and hips. Other symptoms can include painful urination and redness, itching, and discharge in one or both eyes.

Bloodstream infection

This also is known as bacteremia. Shigella infection can damage the lining of the intestines. Rarely, shigella germs enter the blood through the damaged lining and cause a bloodstream infection. These infections are more common in adults with weakened immune systems and in children.

Prevention

Take the following steps to help prevent shigella infection:

  • Wash hands often. Use soap and water, and scrub for at least 20 seconds. This is key before you prepare or eat food, and before sexual activity. It's also important to wash after you use the bathroom or change a diaper.
  • Throw away soiled diapers in a covered, lined garbage can.
  • Disinfect diaper-changing areas right after use, especially if the diaper leaks or spills.
  • Try not to swallow water from ponds, lakes or untreated pools.
  • Do not have sexual contact with anyone who has diarrhea or who recently recovered from diarrhea. Wait at least two weeks.

If you or your child has diarrhea or a known shigella infection, take these steps to prevent spreading germs:

  • Keep washing hands often. And watch small children when they wash their hands.
  • Don't prepare food for others if possible.
  • Stay home from healthcare, food service or child care jobs while sick.
  • Keep children with diarrhea home from child care, play groups or school.
  • Don't go swimming until you have fully recovered.
By Mayo Clinic Staff