Bacillary dysentery, also known as shigellosis, is a potentially dangerous and extremely contagious bacterial infection of the colon. Symptoms develop after an incubation period of one to four days and generally subside within 10 days. (Severe cases may last as long as six weeks, but most cases are mild).

Shigellosis is most prevalent in children between the ages of one and four. Common in overpopulated areas with poor sanitation, shigellosis often occurs in epidemics; isolation or quarantine of affected people is often practiced to curb the spread of the disease. Shigellosis is uncommon in the United States; most citizens who contract it do so while traveling abroad.

What Causes Bacillary Dysentery (Shigellosis)?

  • The shigella bacillus, a bacterium that invades the lining of the colon, is one of several infections that can cause dysentery.
  • Other causes of dysentery include the parasite amoeba and the bacteria E. coli, Yersinia, and others.
  • The shigella bacillus is typically spread via contact with the fecal matter of an infected person.
  • Failure to wash the hands thoroughly after a bowel movement may help to transmit shigellosis.
  • Flies may spread the bacteria from feces (more common in areas with poor sanitation.)
  • Contaminated food or water may spread infection.

Symptoms of Bacillary Dysentery (Shigellosis)

  • Watery diarrhea initially that may evolve to contain mucus and blood
  • Loss of appetite
  • Straining during bowel movements, with accompanying rectal pain
  • Abdominal pain; body aches
  • Nausea and vomiting
  • Fever and chills
  • Rapid dehydration and weight loss. (The very young and the elderly are especially susceptible to dehydration.)

Prevention of Bacillary Dysentery (Shigellosis)

  • To prevent the spread of infection, keep the toilet clean and wash your hands frequently with warm water and soap, especially after a bowel movement or before handling food. (Because dysentery has an incubation period of up to four days, you may be carrying the disease without realizing it.)
  • When traveling abroad or in areas with poor sanitation, drink only bottled or boiled water or other bottled beverages, and eat only cooked foods and fruit you can peel yourself.
  • Avoid contact with infected persons if possible.

Diagnosis of Bacillary Dysentery (Shigellosis)

  • Dysentery is distinguished from more routine causes of infectious diarrhea by the presence of blood.
  • Physical examination and patient history are needed.
  • Stool samples are taken for examination under a microscope and for a laboratory culture to confirm the presence of the shigella bacillus.
  • Colonoscopy to examine the bowels may be performed.
  • Blood tests may be taken to look for electrolyte (essential mineral salt) abnormalities or anemia.

How to Treat Bacillary Dysentery (Shigellosis)

  • A solution of electrolytes (such as sodium and potassium) and fluids may be administered to treat dehydration, although water or other beverages are usually sufficient. In severe cases, fluids must be replaced intravenously.
  • While waiting to see a doctor, prevent dehydration by drinking sports drinks, like Gatorade, or a solution of one teaspoon salt and four teaspoons sugar in one quart of water. It is important to measure accurately: Too much salt may worsen dehydration. Drink one pint each hour while diarrhea persists.
  • Do not take over-the-counter antidiarrheal medications unless otherwise instructed by your doctor. Diarrhea helps rid the body of infectious organisms.
  • Although the infection often clears on its own, antibiotics are often given to limit its transmission. These must be taken for the full term prescribed.
  • Isolation from others is required to prevent spread of the disease.

When to Call a Doctor

  • Call a doctor as soon as you notice symptoms of dysentery. The disease is dangerous and extremely contagious, and should be treated quickly.


Johns Hopkins Symptoms and Remedies: The Complete Home Medical Reference

Simeon Margolis, M.D., Ph.D., Medical Editor

Prepared by the Editors of The Johns Hopkins Medical Letter: Health After 50

Updated by Remedy Health Media

Publication Review By: the Editorial Staff at

Published: 25 Aug 2011

Last Modified: 02 Dec 2014