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Shigella Infection (Shigellosis)

shigella image CDC


Shigellosis is a highly infectious intestinal disease caused by a family of bacteria called Shigella.  



  • The incubation period is 12-96 hours, meaning that illness usually starts between 12 and 96 hours after shigella bacteria enter the body.
  • The main sign of shigella infection is diarrhea, which can be watery, bloody, or both. Many people with shigella also get fever, stomach aches, and nausea.  Vomiting can occur but is not common. 
  • Symptoms typically last 4-7 days. People with mild illness usually get better without specific treatment. 
  • With more severe shigella infection, patients can get diarrhea so severe they become dehydrated. Occasionally, shigellosis causes seizures, bloodstream infection, or arthritis, and can rarely result in death.


How Shigella Spreads

  • Shigella is highly infectious and spreads very easily. Anyone can be infected with Shigella.
  • When people become infected, Shigella organisms are present in their stool or diarrhea.
    • Spread of infection can occur when tiny particles of infected stool enter another person's mouth.
    • In the United States, Shigella infection is usually passed from person-to-person by interpersonal contact.
      • For example, Shigella can be passed among young children in child care who are all handling the same toys, or among homeless adults who are unable to wash hands properly.
  • Shigella has also been known to spread during sexual contact, by eating raw foods contaminated by an infected food handler, or by drinking contaminated liquids.


Diagnosis and Treatment

  • Shigella is diagnosed by health professionals by collecting a sample of stool or diarrhea, and sending it to a microbiology laboratory for culture.
  • Most laboratories are also able to test for antibiotic sensitivities (to find out which antibiotic will be effective in killing the Shigella bacteria).  
  • People with mild illness usually get better on their own, with no specific treatment.
  • However, a course of effective antibiotics can be helpful by shortening the length of illness
  • From a public health viewpoint, effective treatment also makes the patient less infectious to others by reducing diarrhea and eliminating Shigella bacteria from the stool


How to Prevent Shigellosis

  • Handwashing! Thoroughly clean your hands using soap and water or hand sanitizer.  Do this frequently, and before eating, drinking, or touching your face.  Make sure to clean under your nails.
  • Children should be supervised when washing their hands in day care centers and at home.  
  • When possible, young children with a Shigella infection who are still in diapers should not come into contact with uninfected children.
  • During sexual contact, avoid unprotected direct oral-anal contact and be sure to wash hands, other body parts, and any objects thoroughly after sex.
  • In traveling to the developing world where Shigella infection is more common: drink only treated or boiled water, and eat only cooked hot foods or fruits/vegetables you peel yourself after thorough washing.



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