Background The importance of campylobacter as a cause of GE was only recognized in the mid-1970s. They are now the most common known bacterial cause of GE in most developed countries. (In less developed countries, asymptomatic infection is more common.) Campylobacter jejuni is the most common species, but C. coli is common in some areas.
Campylobacter spp. are found in the intestines of many animals and birds, including cattle and horses, household pets, and chickens. Rates of contamination of chicken carcasses vary from >75% in the United Kingdom and The Netherlands to <30% in Sweden and Norway. Some of these differences may be due to the method of isolation used.
The reported incidence of human infection in Western Europe is high. In a survey of 15 countries, the annual incidence varied from 2.9 to 166.8 per 105 population, with a mean of 71 (1999 data). Because these are laboratory-confirmed infections, the true incidence will be considerably higher. The wide range of incidences almost certainly reflects rates of laboratory diagnosis and reporting rather than variation in incidence.
Growth and survival The reason for the late recognition of campylobacters is their fastidiousness: They grow best in an O2 concentration of 5%, in a special medium, and at a temperature of 42 °C. They are also sensitive to heat, being destroyed readily by cooking, and do not survive for long (probably a few hours only) on the surfaces of foods. They nevertheless are highly successful in causing infection, probably because of their ubiquity in the environment, domestic animals, and birds and the small dose required for infection (possibly no more than 200 organisms may be enough).
Characteristic sequence of events and clinical features Although campylobacters undoubtedly cause FP, the source of infection in most instances, especially sporadic cases, is unknown. It is highly probable that many cases, perhaps even most cases, are caused by direct contact with animals, birds, the environment (both domestic and outside), meat carcasses, and possibly other people. Food-borne outbreaks in the past have been traced to untreated water and milk and also milk from bottles whose tops have been pecked by birds. Undercooked poultry is undoubtedly a risk factor, and meat prepared at barbecues, which includes pork, veal, and beef as well as chicken, has also been implicated. In one study, consuming organic products, both meat and vegetables, and eating in a restaurant were risk factors. In another, eating grapes was found to be a risk factor, and salads have also been implicated, but it is possible that some of these foods were contaminated from another source or directly by a food handler.
Other risk factors include travel to foreign countries; handling and cooking of food, especially raw meat; contact with animals and pets (especially those with diarrhea) and visiting an animal farm; swimming; and sailing.
The incubation period of 3-5 days is long compared to that of most other FP bacteria. As with most gastrointestinal (GI) infections with a long incubation period, symptoms are mostly associated with the lower GI tract. Thus, vomiting is uncommon, and abdominal pain and diarrhea are the main symptoms. An accompanying fever is usual, and the diarrhea is often bloody. The illness may last a few days, and the antibiotic ciprofloxacin is now the treatment of choice for severe or prolonged illnesses.
Septicemia or other localized infections are rare complications. One of the well-known complications of campylobacter infection is Guillain-Barre syndrome, in which a symmetrical paralysis affects the body some weeks after the infection. Recovery is usually spontaneous but may take several months. In the acute phases of the illness, respiratory support may be needed.
Diagnosis The organism can be grown from stools, rectal swabs, and food. Special media and O2 concentrations of 5-10% are needed for campylobacter. Two typing systems are available—Penner and Lior.
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