Cincinnati Children's Blog

Shigella Can Put a Damper on Summer Swimming Fun

There is at least one thing that parents don’t want to bring home from the swimming pool this summer: shigellosis.

It’s caused by a group of bacteria called Shigella. Most people infected with Shigella develop diarrhea, fever, and stomach cramps starting a day or two after they are exposed to the bacteria.

One way to get shigellosis is by swimming in contaminated water. And during the summer, a common way to contaminate water is to have infants and toddlers in the pool wearing their diapers.

Shigella bacteria produce toxins that can attack the lining of the large intestine, causing swelling, ulcers on the intestinal wall, and bloody diarrhea.

The severity of the diarrhea sets shigellosis apart from regular diarrhea. In kids with shigellosis, the first bowel movement is often large and watery. Later bowel movements may be smaller, but the diarrhea may have blood and mucus in it.

Other symptoms of shigellosis include:
• abdominal cramps
• high fever
• loss of appetite
• nausea and vomiting
• painful bowel movements


Shigellosis is most likely to occur among toddlers who are not fully toilet-trained. Because it doesn’t take many Shigella bacteria to cause an infection, the illness spreads easily in families, public pools and childcare centers.

Water can become contaminated with Shigella bacteria if sewage runs into it, or if someone with shigellosis swims in or plays in it (especially in splash tables, untreated wading pools, or shallow play fountains used by daycare centers). Shigella infections are acquired by drinking, swimming in, or playing with the contaminated water.

Shigella infections can also be acquired from eating contaminated food infected by people who don’t wash their hands with soap after using the bathroom; eating vegetables contaminated if they are harvested from a field with sewage in it; or flies that breed in infected feces and then contaminate food.

Shigella can be passed in the person’s stool for about 4 weeks even after the obvious symptoms of illness have disappeared (although antibiotic treatment can reduce the excretion of Shigella bacteria in the stool).


The best way to prevent the spread of Shigella is through frequent and careful hand washing with soap, especially after using the toilet and before meals.

If you’re caring for a child who has diarrhea, wash your hands before touching other people and before handling food.

Diapers of a child with shigellosis should be disposed of in a sealed garbage can, and the diaper area should be wiped with disinfectant after use. Young children (especially those still in diapers) with shigellosis or with diarrhea of any cause should be kept away from other kids.

Diagnosis and Treatment

To confirm the diagnosis of shigellosis, your doctor may take a stool sample to be tested for Shigella bacteria. Some cases of shigellosis require no treatment, but antibiotics are often prescribed to help prevent the spread of bacteria to others due to the highly contagious nature of the bacteria.

When to Call the Doctor

Call the doctor if your child has signs of a Shigella infection, including diarrhea with blood or mucus, accompanied by abdominal pain, nausea and vomiting, or high fever.

Robert W. Frenck, Jr., MD, Director of Clinical Medicine at Cincinnati Children’s Division of Infectious Diseases contributed to this article.

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