What Is Shigella Dysenteriae?
Shigella dysenteriae is a species of bacteria that causes severe diarrhea (shigellosis), often referred to as "dysentery." It is most common in developing countries or areas where people live in close contact, such as refugee camps--but according to the Centers for Disease Control and Prevention, about 14,000 cases occur each year in the United States. Shigella dysenteriae type 1 is the virulent form of shigella that causes epidemics.
Symptoms
Symptoms vary, but include cramping, nausea, vomiting, fever, pain in the rectum and watery or bloody diarrhea (often causing dehydration) within two days of infection. Most cases resolve within a week. Infection with S. dysenteriae provides immunity to this strain of shigella, but people can be infected with other strains. Children younger than two years of age are most at risk, because they may develop seizures from the high fever associated with S. dysenteriae. Some diarrhea may persist for weeks or months after infection
Spread of Infection
S. dysenteriae is spread via the fecal-oral route, through ingestion of food or water contaminated with infected stool, or through touching contaminated materials, such as dirty diapers, and then touching the mouth. Even after symptoms of diarrhea subside, the stool continues to carry the bacteria for up to two weeks. Men having sex with men may be at increased risk.
Treatment
S. dysenteriae is increasingly resistant to antibiotics, so doctors often choose to provide supportive treatment, such as fluids, for mild infections and allow the infection to clear without antibiotics. If antibiotics are used, tests (culture and sensitivities) can help to determine which antibiotic is effective. Commonly used drugs include bactrim and ciprofloxacin. Antidiarrheal medications are not effective and may make the infection worse, as they prevent the bacteria from clearing the system.
Complications
In severe cases, the bacteria can spread through the blood, causing a life-threatening infection. According to the National Institute of Allergy and Infectious Disease, S. dysenteriae can cause hemolytic uremic syndrome, which causes severe anemia, hemorrhage, damage to the lining of the intestines and the kidneys (often causing kidney damage or kidney failure), and neurological disorders, such as stroke, paralysis and seizures.
Prevention
No vaccine is available to prevent S. dysenteriae infection, so prevention efforts focus on basic hygiene and sanitation. Handwashing is especially important. Anyone changing soiled diapers should dispose of the diaper in a closed container, as flies can spread the bacteria. Cleanse the diaper-changing area with sanitary wipes and wash the hands thoroughly. People with infection should avoid food preparation until two days after diarrhea has stopped.
