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What is shigella?

Shigella is a germ (bacteria) that causes an infectious disease of the intestines (bowel) called “shigellosis.”

How do people catch shigella?

The germ must be swallowed to cause disease, but only a small number of bacteria are needed to cause illness. The bacteria are often spread when people do not wash their hands with soap and water after using the toilet or changing a diaper. People who get the germs on their hands can infect themselves by eating, smoking, or touching their mouths. People who have sex with people who have the disease are at risk of catching it if there is contact between the mouth and genital area. The germs can also be spread by food or beverages that have been prepared by a person with shigella infection. In rare cases, shigella germs can also be spread through swimming pools that do not have enough disinfectant and filtration or through natural bodies of water such as lakes or ponds that become contaminated.

What are the symptoms of shigella infection?

The most common symptoms are diarrhea, fever, stomach cramps, and straining to go to the bathroom. The stool (feces) may be watery or contain blood, mucus or pus.  Symptoms usually begin 1 to 2 days after the bacteria are swallowed.   The symptoms generally last for five to seven days.

Do all infected people have symptoms?

No. Some only have mild symptoms.  Sometimes people infected with shigella have no symptoms at all, but can still pass the bacteria to others.

How do you know if you have shigella infection?

Your healthcare provider can send a stool (feces) sample to a laboratory.  The laboratory will test the sample for shigella bacteria. 

How is the illness treated?

Persons with mild infections usually recover quickly without antibiotic treatment. However, extra fluids may be needed to prevent dehydration. Antibiotics may be used to treat shigella infection in people who cannot fight off the illness on their own.  Medicines to control diarrhea can make the illness worse and should be avoided.

How can you prevent shigella?

People with shigella infection should not prepare food or drinks for others until they have been shown to no longer be carrying the shigella germ or have had no diarrhea for at least 2 days. The spread of Shigella can be stopped by frequent handwashing with soap and water.

Handwashing saves lives! 

Wash your hands:

  • Before, during, and after preparing food
  • Before eating food
  • After using the toilet
  • After changing diapers or cleaning up a child who has used the toilet 

Healthy Swimming Tips:

  • Do not swallow water or get water in your mouth while swimming.
  • Take a shower before swimming.
  • Do not swim when you have diarrhea.
  • Change diapers in changing rooms, not poolside or on the beach. Wash hands after changing diapers.


Additional Resources:

Boston Public Health Commission
1010 Massachusetts Ave, 6th Floor, Boston, MA 02118.
Phone:(617) 534-5395 Email: