What is Shigella?

Medically Reviewed by Carol DerSarkissian, MD on December 05, 2022
5 min read

You may feel a sharp cramp in your stomach and lower abdomen. Then, you may have the urge to use the bathroom -- as many as 10 to 30 times a day when you have shigellosis, a type of food poisoning.

Caused by a group of bacteria called shigella, this infection can cause belly pain, fever, and watery or bloody diarrhea.

The illness is common among young children, who usually get infected at day care or school. You might also get shigellosis while you’re visiting developing countries where poor hygiene could cause traveler’s diarrhea.

The disease usually goes away in 5 to 7 days with rest and fluids. But in severe cases, you may need to go to the hospital.

Shigellosis is common in the United States with about a half-million cases every year. It’s far more deadly in poorer countries (about 165 million cases and about 1 million deaths worldwide every year).

The Shigella bacteria pass through your stomach and then multiply in your small intestines. They then spread into your large intestines (also known as colon), causing cramping in that part of your body, along with diarrhea.

Shigella leaves the body through human feces. The disease spreads when bacteria from the stool of the sick person go to the mouth of another person.

You may be wondering: How on earth does that happen? Shigella spreads more easily than you might think. Here are some ways:

Touching objects. For example, you may change the diaper of a child who has shigellosis. If you don’t wash your hands thoroughly, you could leave the bacteria behind on objects you touch next, such as changing tables, toys, and doorknobs.

The people who touch those infected surfaces can get infected -- especially if they touch their mouths or swallow something using their contaminated hands.

Eating. People handling or preparing your food may have shigellosis. If their hands aren’t clean, your food may be tainted. Or your fruits and vegetables may have been growing on a field that has been contaminated with human feces.

Swallowing water. You could go swimming in pool or pond and get water in your mouth that’s been contaminated by feces.

Sexual contact. You could get exposed during sexual activity when it involves oral-anal contact.

The main symptom is diarrhea. The stools may be bloody or contain mucus. Other symptoms you or your child may get include:

  • Nausea
  • Vomiting
  • Fever
  • Cramping in your stomach and abdominal area
  • Tenesmus (the feeling that you need to go to the bathroom even when there is nothing left in your intestines)

For people with mild cases, you can expect your symptoms to clear up without drugs in a week.

But shigellosis can be worse on seniors, infants or people who have chronic illnesses that have weakened their immune systems (HIV, for example).

You should call your doctor if:

Not everyone with shigellosis get symptoms. Although you may not have symptoms, you are still infectious and could spread the disease to other people.

You could have lingering effects after a shigella infection, though such cases are rare. Problems may include:

Dehydration. This is when you don’t have enough fluid in your system. You could be lightheaded, dizzy, lack tears, and sunken eyes. Watch for dry diapers in children.

Post-infectious arthritis. This is joint pain (in ankles, knees, feet, hips). You could also get eye irritations and painful urination. This occurs to about 2% of people who get infected with shigella flexneri, a type of shigella bacteria.

Bloodstream infection. When the lining of the intestines gets damaged during the sickness, shigella or other germs in your gut could infect your bloodstream. These infections are more common among people with other illnesses, such as HIV, cancer, or malnutrition.

Hemolytic-uremic syndrome (HUS): This infection produces a toxin that destroys red blood cells, which are cells in your blood that carry oxygen.

Seizures: This is more commonly seen in young children. Call 911 at once if your child has a seizure.

Since there are many causes of diarrhea, a lab test may be needed to figure out whether you have shigellosis. Your doctor may ask you to give a stool sample to see whether you have shigella bacteria.

The lab can run more tests to find out which antibiotic would be the most effective.

In most cases, you can recover from shigellosis by resting and drinking fluids to replace what you’ve lost from diarrhea.

Avoid drugs that stop diarrhea or slow down the gut. Drugs such as diphenoxylate with atropine (Lomotil) or loperamide (Imodium) can make shigellosis worse.

In severe cases, your doctor may prescribe antibiotics to shorten the illness. This may be for seniors, infants, or people who have other diseases. Some shigella bacteria are resistant to antibiotics, so the treatment may not work.

Tell your doctor if prescription antibiotics don’t make you feel better after you’ve taken them for several days.

There is no vaccine or cure, so the key is good hygiene.

Wash your hands well with warm water and soap, especially after using the bathroom or changing diapers, and before preparing food or eating. Also make sure young children wash their hands after using bathroom.

Some other tips:

  • Keep children with diarrhea out of day care or school.
  • Don’t drink water from a pool, lake, or pond.
  • Eat only boiled, cooked, or peeled food while traveling abroad.
  • Wash your hands even more when traveling abroad.
  • Wrap up soiled diapers properly and put them in a trash can.
  • Avoid having sex with someone who had diarrhea recently.