Where does Campylobacter bacteria come from and How do Campylobacter infections spread?

Since 1989, when it surpassed the number of outbreaks caused by salmonella, Campylobacter has been the most common cause of bacterial gastroenteritis in the United States.

An estimated 2.4 million people get infected with it every year. It’s a gram-negative rod-shaped bacterium, and there are three species of it that cause human disease. C. coli causes diarrhea, and C. jejuni is one cause of meningitis in infants.

The third species, which used to be called C. pylori and has recently been renamed Helicobacter pylori, is a nasty germ that causes more than 90 percent of cases of peptic ulcer. C. jejuni and C. coli can turn up in the kitchen. It is less certain where Helicobacter comes from. Undercooked poultry has been identified as a major source of outbreaks, and water can be contaminated with it as well.

Why is Campylobacter infection suddenly so common? First, it really isn’t sudden. In 1886, the bacteriologist Theodore Escherich (after whom Escherichia coli is named) first saw something resembling Campylobacter in the stool of children who had diarrhea, and various scientists over the years noticed the organism in other human patients with diarrhea and in animal tissue as well.

By the early 1970s sophisticated techniques for culturing the organism had been developed, and it then became quite clear that Campylobacter was a very common cause of human illness. So the infection has been around for a long time.

But today the bacterium is flourishing more than ever. Part of the reason is its rapidly developing resistance to antibiotics. The rate of resistant Campylobacter is highest in the industrialized world, where antibiotic use is most widespread. Poultry is a significant carrier of the germ, but within two years of the approval of fluoroquinolone to kill the germ in chickens in the United States in 1995, a Minnesota study showed that resistant strains of C. jejuni doubled the number of cases of illness.

Although Campylobacter can be carried in various ways, including in water, the biggest risk is in handling and eating poultry, particularly eating undercooked chicken. Chickens are chronically infected with it, and almost all raw chicken and other poultry you buy is contaminated with it.

Unpasteurized milk is another source of outbreaks, often involving outbreaks after school field trips to farms during the spring. Sporadic infections usually are most prominent during the summer. For poorly understood reasons, there is an unusual age distribution in the infection: infants have the highest rates, followed by young adults. The lowest rates are among young teenagers and middle-aged and older adults. It may be that infants are more susceptible on first exposure, or that they get more immediate medical care and therefore the disease is diagnosed properly in infants more often than in other age groups. Perhaps young adults are more susceptible because their food is more commonly prepared with poor food handling practices. No one really knows.

Infection with Campylobacter is usually mild. In cases that are serious enough to get reported to the CDC, which is a very small proportion of all cases, the most common symptoms are diarrhea, fever, and abdominal cramps. Bloody diarrhea is a symptom in about half the reported cases, and, rarely, the organism can cause bacteremia (bacterial infection of the blood) and a bone infection that leads to a form of arthritis called Reiter syndrome, in which pain in the joints can last for months and in some rare cases becomes chronic.

About 1 in 1,000 cases of Campylobacter infection is followed by a severe nerve illness called Guillain-Barré syndrome, which can cause paralysis. About 40 percent of Guillain-Barré patients have evidence of a recent case of campylobacteriosis. Both Guillain-Barré syndrome and Reiter syndrome are believed to be caused by an autoimmune response to the infection.

The treatment for Campylobacter infection is usually just supportive, you make the patient comfortable and have him drink plenty of fluids with electrolytes to replace those lost in the diarrhea. In very severe cases of dehydration, intravenous methods may have to be used, but this is uncommon. Campylobacter infections can be treated with antibiotics, tetracycline, chloramphenicol, and erythromycin alone or in combination are effective, but this usually isn’t necessary except in cases where there is very high fever, bloody diarrhea, or more than eight stools in 24 hours. Antibiotic treatment can reduce the duration of illness, but only if it is given quite soon after infection.

To figure out if Campylobacter is the source of your problem, you need to have your blood or other bodily fluid tested. The germ can also be cultured from stool, but that requires a more complicated technique. It is especially important to find out if Campylobacter is the cause in cases of peptic ulcer. If it is, antibiotic treatment is essential.

As few as a couple of hundred Campylobacter bacteria can cause disease, and that amount can easily be present in one tiny drop of raw chicken juice. But it is actually a fairly delicate organism, easily destroyed. It grows best at a temperature between 98.6° and 107.6°F, just about right for the range of temperature inside a human being (or a chicken). If you heat it to more than 131°F for more than a minute or two, it dies. Freezing kills it, too, within a week or so. Moreover, it requires a low-oxygen atmosphere to grow.

Since it is present in stool, Campylobacter can be transmitted from person to person. This won’t happen if everyone washes his or her hands after using the toilet. If you treat all raw meat as if it were infected, you can prevent transmission through food as well. You probably can’t prevent it, however, by buying “clean” chicken, because there is, for all practical purposes, no such thing.

The U.S. Department of Agriculture in 1994 and 1995 found Campylobacter in more than 88 percent of broiler chickens nationwide, so the last chicken you cooked was almost certainly contaminated. But you don’t get sick 9 out of every 10 times you eat a broiler chicken. In fact, you almost never get sick from eating one. This is partly because you’re lucky in that the germ usually doesn’t cause disease even when it is present. Of course, it also helps to follow good food preparation practices.

This means wrapping raw meats so that juice doesn’t drip out of the package, refrigerating foods promptly, keeping cutting boards clean, washing your hands often before and during cooking chores, making sure you cook everything thoroughly, and avoiding eating raw or unpasteurized foods, the same kinds of precautions you would take to prevent other kinds of food-borne illness.