What is dysentery? Dysentery broadly refers to infectious gastrointestinal disorders characterized by inflammation of the intestines, chiefly the colon. The World Health Organization (WHO) defines dysentery as any episode of diarrhea in which blood is present in loose, watery stools. Dysentery is spread among humans through contaminated food and water. Once a person is infected, the infectious organism lives in the intestines and is passed in the stool of the infected person. With some infections, animals can also be infected and spread the disease to humans. Common bacterial causes of dysentery in the United States include infections with the bacteria Shigella and some types of Escherichia coli (E coli). Other less common bacterial causes of bloody diarrhea include Salmonella and Campylobacter infections. Dysentery is associated with environmental conditions where poor sanitation is prevalent. For example, childcare institutions and developing countries have higher rates of Shigella. Amebic dysentery, caused by the parasite Entamoeba histolytica, is most commonly found in tropical areas with crowded living conditions and poor sanitation. The signs and symptoms of dysentery can last five to seven days or even longer. The course of the illness varies among individuals, as do symptoms. Some people suffering with dysentery have mild symptoms, while others may have severe diarrhea with or without vomiting that can pose a risk of dehydration. Fortunately, dysentery can be treated with antibiotics and antiparasitic medications. Untreated dysentery can lead to severe dehydration. Severe dehydration and electrolyte imbalances can result in shock or coma and may be life-threatening. Seek immediate medical care (call 911) if you, or someone you are with, have symptoms of severe dehydration such as confusion, lethargy, loss of consciousness, cold skin, or decreased urine output. Seek prompt medical care if you develop diarrhea and vomiting and believe you may have been exposed to contaminated food or water.