Shigella is a genus of bacteria that are a major cause of diarrheoa and dysentery -- diarrhoea with blood and mucus in the stools -- throughout the world. The bacteria are transmitted by ingestion of contaminated food or water, or through person-to-person contact. In the body, they can invade and destroy the cells lining the large intestine, causing mucosal ulceration and bloody diarrhoea.

Apart from diarrhoea, symptoms of Shigella infection include fever, abdominal cramps, and rectal pain. Most patients recover without complications within seven days. Shigellosis can be treated with antibiotics, although some strains have developed drug resistance.

Shigellosis

Shigellosis is an infectious disease caused by a group of bacteria called Shigella. Most who are infected with Shigella develop diarrhea, fever, and stomach cramps starting a day or two after they are exposed to the bacteria. The diarrhea is often bloody. Shigellosis usually resolves in 5 to 7 days. Persons with shigellosis in the United States rarely require hospitalization. A severe infection with high fever may 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 pass the Shigella bacteria to others.

The Shigella germ is actually a family of bacteria that can cause diarrhea in humans. They are microscopic living creatures that pass from person to person. Shigella were discovered over 100 years ago by a Japanese scientist named Shiga, for whom they are named. There are several different kinds of Shigella bacteria: Shigella sonnei, also known as "Group D" Shigella, accounts for over two-thirds of shigellosis in the United States. Shigella flexneri, or "group B" Shigella, accounts for almost all the rest. Other types of Shigella are rare in this country, though they continue to be important causes of disease in the developing world. One type found in the developing world, Shigella dysenteriae type 1, can cause deadly epidemics.'

Diarrhoea

Though the global under-five mortality from acute diarrhea has decreased from 4.5 million to 1.8 million annually, acute diarrhea continues to take a huge toll on children's health in developing countries. (WHO 2006) Diarrhea represents a significant burden on the health system, the household, and the nutritional status of children. (Bateman and McGahey 2001)

Diarrhea is the second leading killer of children under the age of five, accounting for approximately 15% of under-five child deaths worldwide, or almost two million deaths annually. (WHO 2003)

Although the means to prevent diarrhea through water supply, sanitation, and hygiene have been well documented, each year roughly one and one half billion episodes of acute diarrhea occur among children under the age of five.

Diarrhea may be caused by a temporary problem, like an infection, or a chronic problem, like an intestinal disease. A few of the more common causes of diarrhea are

• Bacterial infections. Several types of bacteria, consumed through contaminated food or water, can cause diarrhea. Common culprits include Campylobacter, Salmonella, Shigella, and Escherichia coli.
• Viral infections. Many viruses cause diarrhea, including rotavirus, Norwalk virus, cytomegalovirus, herpes simplex virus, and viral hepatitis.
• Food intolerances. Some people are unable to digest a component of food, such as lactose, the sugar found in milk.
• Parasites. Parasites can enter the body through food or water and settle in the digestive system. Parasites that cause diarrhea include Giardia lamblia, Entamoeba histolytica, and Cryptosporidium.
• Reaction to medicines, such as antibiotics, blood pressure medications, and antacids containing magnesium.
• Intestinal diseases, like inflammatory bowel disease or celiac disease.
• Functional bowel disorders, such as irritable bowel syndrome, in which the intestines do not work normally.

References

Centers for Disease Control and Prevention

World Health Organization - Diarrhoeal disease

Rehydration Project