Shigellosis (Bacillary Dysentery)

Shigellosis is an infection of the intestine that causes frequent watery diarrhea. It spread through eating or drinking contaminated food or water, or through direct contact with an infected person.

What Is Shigellosis?

Shigellosis, which is very contagious, is an infectious disease of the intestine that is spread through the ingestion (eating and drinking) of contaminated food and water. It can also be transmitted from one person to another by direct contact or by touching or handling surfaces contaminated with Shigella bacteria * . Shigellosis causes watery diarrhea, also called dysentery. Watery diarrhea means that the person has frequent bowel movements that are liquid in nature. Often the person feels unable to control the diarrhea. The diarrhea may contain blood, pus, and mucus. If the diarrhea is severe, the person may become dehydrated * from losing too much body fluid.

How Common Is Shigellosis?

According to the Centers for Disease Control and Prevention (CDC), there are about 500,000 cases of shigellosis in the United States every year. Up to 20 percent of people who become infected require hospitalization due to the severity of the infection.

What Are the Causes of Shigellosis?

Shigellosis is caused by the Shigella bacterium. There are four groups of Shigella bacteria that can cause shigellosis in humans. According to the National Institute of Allergy and Infectious Diseases, the most common type of Shigella bacteria in developed countries, including the United States, is Shigella sonnei. Shigellosis outbreaks are most common in tropical or temperate climates as well as in crowded areas with poor hygiene. They are also most common in day care and institutional settings, such as schools.

Who Is at Risk of Shigellosis?

According to the CDC, there are several groups that are at increased risk of getting shigellosis:

What Are the Symptoms of Shigellosis?

Signs of shigellosis usually start one to two days after exposure to the Shigella bacteria and include diarrhea, fever, tiredness, abdominal pain, nausea and vomiting, and a painful feeling of needing to have a bowel movement even when the bowel is empty. This uncomfortable feeling is called tenesmus. Diarrhea associated with Shigella infection typically lasts for 5 to 7 days.

How Is Shigellosis Diagnosed?

The healthcare provider obtains a health history and asks questions about symptoms, contact with other people who have had similar symptoms or who have been diagnosed with shigellosis, travel outside the country (especially if the person traveled to a developing country), and sexual orientation. Tests of stool samples can be done to determine whether Shigella bacteria are present. Cultures * of the stool sample can also be done to determine which antibiotics will be most effective in treating the disease. A culture is done by swabbing a bit of the stool sample on a culture plate, called an agar plate, and then allowing the organism to grow. Samples of antibiotic are placed on the culture plate to determine which is most effective in killing the grown bacteria. This process may take several days.

How Do Doctors Treat Shigellosis?

How Can Shigellosis Be Prevented?

There are several measures that can be taken to prevent shigellosis:

See also AIDS and HIV Infection • Antibiotic Resistance • Bacterial Infections • Diarrhea • Fluid and Electrolyte Disorders • Food Poisoning • Global Health Issues: Overview • Infection • Intestinal Infections • Travel-Related Infections: Overview


Books and Articles

Anderson, Rodney P., and Linda Young. Case Studies in Microbiology: A Personal Approach. Hoboken, NJ: Wiley, 2012.

Guandalini. Stefano, and Haleh Vaziri, eds. Diarrhea: Diagnostic and Therapeutic Advances. New York: Springer, 2011.

Merck Manual: Consumer Version. “Shigellosis.” (accessed July 9, 2016).


Centers for Disease Control and Prevention (CDC). “Shigella – Shigellosis.” (accessed July 9, 2016).

National Institute of Allergy and Infectious Diseases. “Shigellosis.” (accessed July 9, 2016).


Centers for Disease Control and Prevention. 1600 Clifton Rd., Atlanta, GA 30329-4027. Toll-free: 800-CDC-INFO (800-232-4636). Website: (accessed July 9, 2016).

* bacteria (bak-TEER-ee-a) are single-celled microorganisms, which typically reproduce by cell division. Some but not all types of bacteria can cause disease in humans. Many types can live in the body without causing harm.

* dehydrated is a term used when there is loss of large amounts of water or body fluids from the body.

* infection (in-FEK-shun) is the invasion and proliferation of microorganisms in the body.

* developing countries are countries that are poor but are seeking to become more advanced both economically and socially.

* antibiotic (an-tie-by-AH-tik) is a drug that kills or slows the growth of bacteria.

* culture (KUL-chur) is a test in which a sample of fluid or tissue from the body is placed in a dish containing material that supports the growth of certain organisms. Typically, within days the organisms will grow and can be identified.

  This information is not a tool for self-diagnosis or a substitute for professional care.