Following an imaginary Campylobacter population from farm to fork and beyond: a bacterial perspective

It has been known for decades that poultry meat is the most common single source for campylobacteriosis, yet the problem has not been solved. This review identifies some of the reasons why our attempts to reduce the incidence of this pathogen have largely failed. Based on the literature, the events a virtual population of Campylobacter may encounter, from growing in the gut of a broiler to eventually infecting humans and causing disease, are reviewed. Most steps in the farm-to-fork process are well studied, though there are gaps in our knowledge about survival and spread of Campylobacter populations before they enter the farm. Key events in the farm-to-fork chain that are suitable targets for prevention and control, to reduce food-borne campylobacteriosis, are indicated. Novel insights into the pathogenic mechanism responsible for disease in humans are summarized, which hypothesize that an overactive immune response is the reason for the typical inflammatory diarrhoea. A role of genetic microheterogeneity within a clonal population in this chain of events is being proposed here. The human host is not necessary for the survival of the bacterial species, nor have these bacteria specifically evolved to cause disease in that host. More likely, the species evolved for a commensal life in birds, and human disease can be considered as collateral damage owing to an unfortunate host-microbe interaction. The indirect environmental burden that results from poultry production should not be ignored as it may pose a diffuse, but possibly significant risk factor for disease.