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Public Health Solutions
District Health Department
995 East Hwy 33, Ste 1
Crete, NE 68333-2562
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Shigella
What is Shigella?
Shigella is a highly contagious bacterium which infects the intestinal tract. The genus Shigella consists of four species:
- Group A, Shigella dysenteriae;
- Group B, S. flexneri;
- Group C, S. boydii; and
- Group D, S. sonnei.
In general, S. dysenteriae, S. flexneri, and S. boydii account for most isolates in developing countries. Conversely, S. sonnei is most common and S. dysenteriae is least common in developed countries.
How are Shigella spread?
Shigella is spread by direct or indirect contact with infected individuals. Food or water may be contaminated by direct or indirect contact with fecal material from infected people. Shigella often causes outbreaks in daycare centers. Parents often acquire the illness from their children.
What are the symptoms of Shigella infection?
Symptoms include diarrhea which may be mild or severe, along with fever and nausea. The diarrhea may be watery or bloody. Vomiting and abdominal cramping may also occur. Some infected people may not show any symptoms.
When do the symptoms appear?
Symptoms appear within 12 to 96 hours (usually 1-3 days) after exposure to Shigella, or within one week for S. dysenteriae.
Are Shigella infections treatable?
Most people will recover on their own, usually within 4-7 days. Fluid and electrolyte replacement may be necessary if the diarrhea is watery and signs of dehydration are present. Antibiotics are occasionally used to treat severe infections or to shorten the carrier state, which may be important for food handlers, those who attend or work in child care, or institutionalized individuals.
How long is an infected person communicable?
An infected person is contagious until the organism is not present in the his/her stool. For most people this will be for one to two weeks, rarely does it exceed four weeks. Certain antibiotics may shorten this period.
Should infected people be excluded from work or school?
Since the bacteria is passed in the stools of infected people, those with active diarrhea or those who are unable to control their bowel habits should be isolated. In general, once diarrhea has ceased, people can return to work or school. Food handlers, children or staff in daycare, or health care workers must have two negative stool cultures collected 24 hours apart. If they were on antibiotics for their illness, the first specimen needs to be collected 24 hours after completion of antibiotic therapy.
Do Shigella infections confer immunity to future Shigella infections?
Studies have indicated that a degree of homologous immunity can be demonstrated among those who have recovered from a Shigella infection. It has been theorized that the immunity against Shigella was due essentially to the sensitization of the intestinal mucosa to Shigella, and that antibodies circulating in the serum have a negligible role in protection.
What can be done to prevent the spread of Shigella?
The best way to prevent the spread Shigella is careful handwashing using warm, soapy water after using the toilet or changing diapers.
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