Campylobacter means “curved rod” in Greek, which describes the shape of the bacterium. It is a Gram-negative, motile, bacterium that prefers a little oxygen in order to grow (microaerophilic). The bacteria often appear in pairs or short chains making them look like the wings of a gull. Campylobacter produces a powerful urease that can split urea to release ammonia. This raises the pH in the environment, protecting the bacterium from such acidic environments as that of the human stomach.
Although four groups of campylobacter cause human enteritis, only two are responsible for the vast majority of cases: C. jejuni, accounting for 98% of the cases in Canada and the UK, and C. coli, accounting for 40% in Poland and parts of Central Africa. C. laridis and C. upsaliensis are both now known as C. lari.
Campylobacter pylori was first isolated in 1982 from a stomach biopsy. However, it was found to differ from other Campylobacter species and was reclassified to a new genus called Helicobacter and given the species name of H. pylor. The genera Vibrio, Camplobacter, and Helicobacter were at one time thought to be but one genus because they are closely related in morphology and biochemistry.
Campylobacter is found mainly in the intestines of many birds and mammals, including poultry and cattle. Although it does not commonly cause disease in these hosts, it can cause colicky abdominal pain and diarrhea in humans. The infection is most prevalent in June, for some reason, and is considered to be one of the “Big Four enteric pathogens” (the other three being Shigella, Salmonella, and Giardia). It is responsible for as much as 15% of all known diarrheal cases worldwide and has been linked as the cause of peptic ulcers, afflicting 10% of the American population. It has also recently been linked to a growing list of diseases, including heart disease and some autoimmune diseases. Campylobacter is rapidly overtaking the mortality rate of E. coli 0157:H7 and is surpassing it in frequency.
Campylobacters produce a toxin that is genetically related to the cholera toxin. Drinking contaminated water or milk or eating contaminated food are the major modes of transmission. Since they do not replicate in food but only use it as a vector, campylobacter is considered a food-borne infection rather than a food poisoning. The incubation period is from fifteen hours to several days, depending on how much was consumed. Symptoms of infection include fever, bloody diarrhea, headache, and abdominal pain. It usually lasts six to ten days, but sometimes a chronic condition develops. Systemic infections can also develop in those whose immune systems have been compromised. A number of antibiotics are used to reduce the length and severity of the illness. Relapses are becoming more common, with the disease becoming severe, prolonged, and life-threatening. It is now thought that about 40% of the cases of Guillain-Barré syndrome stem from an infection of Campylobacter.
Major food sources of the campylobacter bacterium are pork, turkeys, and raw or undercooked fish, especially shellfish. Mushrooms can also be a source, and chickens are responsible for about one-half of all the cases. Wild birds can also act as an unusual vector – magpies and jackdaws especially, when they come in contact with human foods. An example is England, where milk is still delivered in bottles door to door. When birds began pecking at the caps and infecting the milk, new caps had to be designed to prevent the birds from breaking through.
Ingestion of several hundred Campylobacter jejuni bacteria causes the disease campylobacteriosis. Young children can become infected from puppies or kittens with diarrhea. The traveller’s diarrhea is often caused by this particular organism. Symptoms include diarrhea, abdominal pain, tiredness, headaches, muscle aches,and nausea. Bloody diarrhea is common, but not vomiting. Some have been known to have twenty or thirty watery bloody stools in one day, robbing the body of vital electroytes, iron, and nutrients. The organism generally takes two to ten days to incubate. Without antibiotics, stools can be infectious for several weeks, whereas three days of antibiotics can clear the stool. When the disease is over, no one can become a carrier to infect others.