Although campylobacter was first identified in 1909 as an animal pathogen, due to better isolation methodology in recent years it is now recognized as one of the leading causes of diarrhea in humans. They are small nonsporing, gramnegative motile bacteria with spiral or S-shaped morphology and can only grow under conditions of reduced oxygen tension. Campylobacter organisms are sensitive to drying or freezing, but they can survive in the environment in cold ground-water, soil, and in refrigerated food for weeks. Campylobacters are found in the gastrointestinal tract of domestic and wild animals and can cause human infections through direct contact or through food or water vehicles. Poultry, cattle, swine, and sheep are the main reservoirs, and campylobacters can cause abortions and diarrhea in these animals.
Two main species affect humans, C. jejuni and C. coli, with most cases attributed to the former. Virulence factors include rapid motility, outer membrane protein for adherence, and possibly enterotoxin. The diarrhea caused by campylobacter is often mild, but may be marked by profuse, foul-smelling stools with blood or mucus, accompanied by abdominal cramping. Symptoms can be severe enough to mimic appendicitis, although death is rare. Sequelae such as reactive arthritis may follow, but the most serious of these is Guillain-Barré syndrome. For these reasons, the costs for campylobacteriosis are high (up to $1.4 billion annually in the United States). Immunocompromised people are susceptible, and young adults also appear to be a high-risk group, possibly due to inadequate understanding of food safety and undercooking of poultry. Based on routine surveillance, children under five years of age have the highest incidence.
Most campylobacteriosis cases are sporadic, peaking in the summer months. The estimated annual incidence of campylobacteriosis in the United States and United Kingdom is about the same, between 1,000 and 1,100 cases per 100,000 persons. In developing countries the rate is believed to be higher, especially in children under five. Risk factors include direct contact with farm animals, animal carcasses, or household pets— especially puppies and kittens with diarrhea. Person-to-person transmission occurs within families. Perinatal transmission is rare. Unlike Salmonella and other food-borne disease organisms, Campylobacter subspecies tend not to multiply in food, but they can be found in large numbers in raw sewage and fecally contaminated surface waters. Raw chicken is the food most commonly associated with campylobacteriosis. Because of the low infective dose, it is possible to transfer sufficient organisms to the mouth by direct contact with the chicken or its drip waters to cause illness.
In addition, consumption of untreated water and milk has been associated with large outbreaks— 500 joggers in Switzerland became ill after drinking a raw milk beverage, and 2,500 school children aged 2 to 7 were infected by raw milk in England. In Sweden, between 1992 and 1996, six waterborne outbreaks were recorded, affecting about 6,000 persons. Water treatment, pasteurization of milk, and proper hygiene by the public are the most
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Center for Food Safety and Applied Nutrition (2001). "Campylobacter jejuni." In Bad Bug Book (Foodborne Pathogenic Microorganisms and Natural Toxins Handbook). Washington, DC: U.S. Food and Drug Administration. Available at http://vm.cfsan.fda.gov/~mow/chap4.html.
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