Shigellosis
Overview
Shigellosis, also known as bacillary dysentery in its most severe manifestation, is a foodborne illness caused by infection by bacteria of the genus Shigella. It accounts for less than 10% of the reported outbreaks of foodborne illness in the USA. Shigellosis rarely occurs in animals other than humans and other primates like monkeys and chimpanzees. The causative organism is frequently found in water polluted with human feces, and is transmitted via the fecal-oral route. The usual mode of transmission is directly person-to-person hand-to-mouth, in the setting of poor hygiene among children. Ten to fifteen (10-15)% of people affected will die. In the developing world, Shigella causes approximately 165 million cases of severe dysentery and more than 1 million deaths each year, mostly in children in the developing world. Shigella also causes approximately 580,000 cases annually among travelers and military personnel from industrialized countries.
Symptoms
Symptoms may range from mild abdominal discomfort to full-blown dysentery characterized by cramps, diarrhoea, fever, vomiting, blood, pus, or mucus in stools or tenesmus. Onset time is 12 to 50 hours. Infections are associated mucosal ulceration, rectal bleeding, drastic dehydration; fatality may be as high as 10-15% with some strains. Reiter's disease and hemolytic uremic syndrome are possible sequelae that have been reported in the aftermath of shigellosis. Shigella can be transmitted through food. Food known to do so includes salads (potato, tuna, shrimp, macaroni, and chicken), raw vegetables, milk and dairy products, and meat. Contamination of these foods is usually through the fecal-oral route. Fecally contaminated water and unsanitary handling by food handlers are the most common causes of contamination. An estimated 18,000 cases of shigellosis occur annually in the United States. Infants, the elderly, and the infirm are susceptible to the severest symptoms of disease, but all humans are susceptible to some degree. Shigellosis is a very common malady suffered by individuals with Acquired Immune Deficiency Syndrome (AIDS) and AIDS-related complex. Shigellosis is a more common and serious condition in the developing world.
Prevention
Simple precautions can be taken to prevent getting Shigellosis: wash hands before handling food and thoroughly cook all food before eating. In addition to improved sanitation and hygiene, several vaccine candidates for Shigella are in various stages of development. According to the World Health Organization, candidates include live attenudated, conjugate, ribosomal, and proteosome vaccines.
Treatment
Treatment consists mainly of replacing fluids and salts lost because of diarrhea. Oral replacement is satisfactory for most people, but some may need to receive fluids intravenously. In most cases, the disease resolves within 4 to 8 days without antibiotics. Severe infections may last 3 to 6 weeks. Antibiotics such as trimethoprim-sulfamethoxazole, norfloxacin, ciprofloxacin, or furazolidone may be given when the person is very young or very old, when the disease is severe, or when there is a high risk of the infection spreading to other people. The severity of the symptoms and the length of time the stool contains Shigella are reduced with antibiotics. Antidiarrheal drugs (such as diphenoxylate or loperamide) may prolong the infection and should not be used.