Campylobacter, KAM pih loh BAK tuhr, are a kind of bacteria that can cause a form of food poisoning. The illness, called campylobacteriosis, is usually caused by the bacterium Campylobacter jejuni. The bacterium occurs in unclean water and also in many types of livestock, including chickens, turkeys, and pigs. Scientists did not recognize Campylobacter as a cause of food-borne illness until the 1970's. However, health officials now believe that campylobacteriosis is the most common form of bacterial food poisoning in the United States.