Bids become infected by consuming faeces (the faeco-oral route) and, since they are enteric bacteria Campylobacter Spp are able to survive in the harsh environment of the digestive tract Campylobacter sends to colonise the lower intestines, especially the caecal region
This bacterium does not attach itself to the gut wall but remains in the mucus in the caecal crypts This mucus can protect Campylobacter Spp from many of the feed additives that are effective against salmonella. Lesions are rarely formed and invasion of the gut lining is also rare.
Once infected the population of Campylobacter spp. increases dramatically-up to 1,000 million or more per gram of caecal contents or faeces
The colonisation of the caeca is influenced by campylobacter genetic factors

Although the establishment of Campylobacter spp. in the caeca is not a true infection, general and local humoral immune responses are often initiated with the appearance of antibodies a couple of weeks after infection. Cellular immunity has not been described
Antibodies thus produced can be easily transfered to the chick whom they protect against Infection

Public health importance
Campylobacteriosis or campylobacter enteritis is a major, not the major cause of human food poisoning in many countries in the third world campylobacter is a common cause of infantile diarrhoea
Inman campylobacter infection is characterised by a self-limiting watery and/or bloody diarrhoea. Serious complications such as Reiter’s syndrome an arthria), Guillain-Basyndrome nephritis, myocarditis, cystitis, and septic abortion can arise
Campylobacter can contaminate poultry meat, with up to 70% of the disease in man being epidemiologically linked to the consumption of poultry meat. The importance of a very low infective dose in the epidemiology of human campylobacteriosis should not be underestimated