Shigella bacteria are found in the intestines and stool of infected people who, in turn, may contaminate food or water. The bacteria are spread by direct contact with an infected person, by eating or drinking contaminated food or water, or by contact with a contaminated object. Some infected people may not show any symptoms. The symptoms usually appear one to three days after exposure, and usually last for four to seven days. People with shigellosis may be able to spread the disease even after they are well.
Most people pass the shigella bacteria in their stool for one to two weeks.
Sometimes people continue to pass the bacteria for as long as six weeks. Since the germ is passed in the stool of an infected person, people with active diarrhea or those who are unable to control their bowel habits should be isolated. Most infected people may return to work or school when their diarrhea stops if they carefully wash their hands after visits to the toilet. Food handlers, children and staff in day care settings, and health care workers must obtain the approval of the local or state health department before returning to their routine activities. Most people with shigellosis will recover on their own.