Shigellosis

Shigellosis is an infectious disease caused by various species of Shigella. People infected with Shigella develop diarrhea, fever and stomach cramps starting a day or two after they are exposed to the bacterium. The diarrhea is often bloody. Shigellosis usually resolves in 5 to 7 days, but in some persons, especially young children and the elderly, the diarrhea can be so severe that the patient needs to be hospitalized. A severe infection with high fever may also be associated with seizures in children less than 2 years old. Some persons who are infected may have no symptoms at all, but may still transmit the bacteria to others.

Shigella were discovered over 100 years ago by the Japanese microbiologist, Shiga, for whom the genus is named. There are four species of Shigella: S. boydii, S. dysenteriae, S. flexneri, and S. sonnei. Shigella sonnei, also known as Group D Shigella, accounts for over two-thirds of the shigellosis in the United States. Shigella flexneri, or Group B Shigella, accounts for almost all of the rest. Other types of Shigella are rare in this country, although they are important causes of disease in the developing world. One type, Shigella dysenteriae type 1, causes deadly epidemics in many developing regions and nations.