Microorganisms - Campylobacter

Campylobacter is part of the natural gut microflora of many of the animals that humans eat - chickens, turkeys, swine, cattle and sheep. A contaminated poultry carcass can carry anywhere between 100 and 100,000 Campylobacter cells. Given that it only takes 500 Campylobacter cells to cause infection, consumers can face significant risk.

There are 17 known species of Campylobacter, and at least a dozen species have been implicated in human illness. The most infamous is Campylobacter jejuni, a nonsporeforming, Gram-negative rod, recognized as one of the main culprits overall for bacterial foodborne illnesses. Scientists estimate that more than 80 percent of Campylobacter infections are caused by C. jejuni.

C. jejuni and the other members of the Campylobacter genus grow at lower than atmospheric oxygen concentrations, typically 3 to 5 percent. Consequently, they are somewhat fragile in the ambient environment and difficult to culture in the laboratory.

The main food sources linked to C. jejuni infections include improperly handled or undercooked poultry products, raw milk, cheeses made from unpasteurized milk and contaminated water. It's worth noting, though, that C. jejuni has occasionally found in a variety of other places, from vegetables to seafood to pond water.

Campylobacter species are among the leading causes of domestically acquired bacterial foodborne illness in the United States, with nearly 1.3 million cases occurring annually, according to data from the U.S. Centers for Disease Control and Prevention (CDC). For each reported case of campylobacteriosis, 30 cases are projected to be unreported.

Overall the CDC attributes an estimated 76 deaths in the United States per year to campylobacteriosis. And in addition to causing fatalities, C. jejuni has also been linked to autoimmune disorders with scientists believing that antigens present in the pathogen resemble those in certain nervous tissues in humans and lead to reactions. Children less than 5 years old (especially less than 1 year) and young adults between 15 and 29 years in age are C. jejuni's most common human hosts. The bacterium also has a disproportionally large effect on pregnant women, not only sickening them but causing infection in their fetuses, which can sometimes lead to miscarriage or stillbirth.