Campylobacter jejuni is responsible for 80-90% of Campylobacter infections in most parts of the world. Campylobacters are very specific in their requirements for growth needing relatively high temperatures and microaerophilic (low oxygen levels) conditions. They do not, therefore, normally grow in food, which distinguishes them from other food-poisoning bacteria. However, as the infective dose for Campylobacter enteritis is thought to be low (< 500 organisms) and the fact that the organism can survive for a period of time in food, especially at refrigeration temperatures, Campylobacter is a leading cause of bacterial gastrointestinal illness. Campylobacter coli can also cause gastroenteritis.

Symptoms of Campylobacter enteritis can range from mild to quite severe. Almost all cases experience diarrhoea, whilst vomiting is rare. Death from Campylobacter enteritis is rare.

Campylobacter is found in the intestinal tract of a wide range of warm-blooded animals, especially birds. Wild birds are thought to be an important reservoir of infection for pets and food animals. Poultry is, therefore, a natural host for Campylobacter. It has also been isolated from sewage, river water and carrier food handlers.

Foods from which Campylobacter is commonly isolated are: poultry carcasses, offal (pigs, cows and sheep), beef, pork, lamb, cooked meats, egg and raw milk.

Campylobacter require very specific conditions for growth. Campylobacter jejuni and Campylobacter coli can only grow at temperatures above 30ºC (their optimum is between 42º and 45ºC). Growth at these temperatures will be slow unless the atmosphere and nutrients available are favourable.

Campylobacter jejuni is very heat sensitive. Death occurs at temperatures of 48C and higher, so the organism will not survive milk pasteurisation or heat treatments of meats sufficient to kill Salmonella.