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Campylobacter jejuni (pronounced “camp-e-low-back-ter j-june-eye”) is a bacterium that was first recognized as a cause of human gastrointestinal illness in 1975. Since that time, the bacterium has been identified as the most common cause of bacterial foodborne illness in the U.S., ahead of Salmonella – the second most common cause (MMWR Weekly, 2000, March 17; Tauxe, 1992).
Over 10,000 cases are reported to the Centers for Disease Control and Prevention (CDC) each year; however, many more cases go undiagnosed or unreported and estimates are that Campylobacter causes 2 to 4 million cases per year in the United States. Active surveillance for cases indicates that over 20 cases for each 100,000 persons in the population are diagnosed yearly, and 124 deaths are attributed to C. jejuni annually (CDC, 2005, October 6). Current estimates are that each case of campylobacteriosis costs $920 on average due to medical and productivity (lost wages) expenses with an annual total cost of approximately $1 billion (CAST, 1994). The CDC reported that the incidence of Campylobacter infection decreased by 30 percent in the ten-year period between 1996 and 2006 (MMWR, 2007, April 13).
Campylobacter jejuni is a gram-negative, microaerophilic, thermophilic rod that grows best at 42°C (107°F) and low oxygen concentrations. These characteristics are adaptations for growth in its normal habitat – the intestines of warm-blooded birds and mammals. Several closely related species with similar characteristics, C. coli, C. fetus, and C. upsalienis, may also cause disease in man but are responsible for less than one percent of human infections annually (CDC, 2005, October 6).
Food is the most common vehicle for the spread of Campylobacter, and chicken is the most common food implicated. Contamination occurs during animal slaughter and processing when it comes into contact with animal feces. Ingestion of as few as 500 organisms – an amount that can be found in one drop of chicken juice – has been proven to cause human illness (FSIS, 1996; Tauxe, 1992). Despite this low infectious dose and the prevalence of Campylobacter jejuni in the environment, most cases of Campylobacter infection occur as isolated, sporadic events, and are not usually a part of large outbreaks. But, very large outbreaks (>1,000 illnesses) of campylobacteriosis have been documented, most often from consumption of contaminated milk or unchlorinated water supplies.
A 1998 Consumer Reports study identified Campylobacter in 63% of more than 1000 chickens obtained in grocery stores (Consumers Union, 1998), and other studies have documented Campylobacter contamination on up to 88 percent of chicken carcasses (FSIS, 1996; Tauxe, 1992). Any raw poultry – chicken, turkey, duck, goose, game fowl – meat and its juices may contain Campylobacter, including organic and “free range” products. Other identified food vehicles include unpasteurized milk, undercooked meats such as beef, pork, lamb, and livestock offal, and occasionally shellfish, fresh produce, and eggs.
Symptoms of Campylobacter infection
The illness caused by ingestion of Campylobacter bacteria is called campylobacteriosis. Diarrhea is the most consistent and prominent manifestation of campylobacteriosis, and is often bloody (MMWR, 2000, March 17). Typical symptoms of C. jejuni infection also include fever, nausea, vomiting, abdominal pain, headache, and muscle pain. A majority of cases are mild, do not require hospitalization, and may be self-limited; however, Campylobacter jejuni infection can be severe and life-threatening. Death is more common when other diseases (e.g., cancer, liver disease, and immuno-deficiency diseases) are present.
Children under the age of five and young adults aged 15-29 are the age groups most frequently affected. The incubation period – the time between exposure to the bacterium and the onset of the first symptom – is typically two to five days, but onset may occur as many as 10 days after ingestion (MMWR Surveillance Summaries, 2000, March 17). The illness usually lasts no more than one week; however, severe cases may persist for up to three weeks, and roughly 25% of individuals experience symptom relapse.
Diagnosis of Campylobacter infection
Many kinds of infections can cause diarrhea and the other symptoms associated with campylobacteriosis. Doctors can look for bacterial causes of diarrhea by asking a laboratory to culture a sample of stool from an ill person. Microbiology laboratories now routinely perform culture procedures on stool specimens that are specifically designed to promote the growth and identification of Campylobacter jejuni and the other species of Campylobacter.
Many persons submit samples for culturing after they have started antibiotics, which may make it even more difficult for a lab to grow Campylobacter. Blood cultures are often not performed and in most cases the blood stream is not infected.
Complications of Campylobacter infection
Long-term consequences can sometimes result from a Campylobacter infection. Some people may develop a rare disease that affects the nerves of the body following campylobacteriosis. This disease is called Guillain-Barré syndrome (GBS). Although rare, it is the most common cause of acute generalized paralysis in the Western world. It begins several weeks after the diarrheal illness in a small percentage of Campylobacter victims. GBS occurs when a person’s immune system makes antibodies against components of Campylobacter and these antibodies attack components of the body’s nerve cells because they are chemically similar to bacterial components (Ang, et al., 2001).
It is estimated that approximately one in every 1000 reported campylobacteriosis cases leads Guillain-Barré syndrome (CDC, 2005, October 6). As many as 40% of Guillain-Barré syndrome cases in this country occur following campylobacteriosis (Rees, et al., 1995). Miller Fisher Syndrome is another, related neurological syndrome that can follow campylobacteriosis and is also caused by immunologic mimicry (Ang, et al., 2001).
Another chronic condition that may be associated with Campylobacter infection is an arthritis called Reactive Arthritis. This is a reactive arthritis that most commonly affects large weight-bearing joints such as the knees and the lower back. It is a complication that is strongly associated with a particular genetic make-up; persons who have the human lymphocyte antigen B27 (HLA-B27) are most susceptible.
Campylobacter may also cause appendicitis or infect the abdominal cavity (peritonitis), the heart (carditis), the central nervous system (meningitis), the gallbladder (cholecystitis) the urinary tract, and the blood stream.
Preventing Campylobacter infection
The single most important and reliable step to preventing Campylobacter infection is to adequately cook all poultry products. Make sure that the thickest part of the bird (the center of the breast) reaches 180 degrees F or higher. It is recommended that the temperature reaches at least 165 degrees F for stuffing and 170 degrees F for ground poultry products, and that thighs and wings be cooked until juices run clear. Do not cook stuffing inside the bird.
Transport meat and poultry home from the market in the coolest part of the vehicle (generally the trunk in winter and cab in summer). Defrost meat and poultry in the refrigerator. Place the item on a low shelf, on a wide pan, lined with paper towel; ensure that drippings do not land on foods below. If there is not enough time to defrost in the refrigerator, use the microwave.
Rapidly cool leftovers. Never leave food out at room temperature (either during preparation or after cooking) for more than 2 hours.
Avoid raw milk products.
Wash fruits and vegetables carefully, particularly if they are eaten raw. If possible, vegetables and fruits should be peeled.
Wash hands thoroughly using soap and water, concentrate on fingertips and nail creases, and dry completely with a disposable paper towel after contact with pets, especially puppies, or farm animals; before and after preparing food, especially poultry; and after changing diapers or having contact with an individual with an intestinal infection. Children should wash their hands on arrival home from school or daycare.