Campylobacter: Animal Reservoirs, Human Infections, and Options for Control

Abstract

Campylobacteriosis is a frequently diagnosed disease in humans. Most infections are considered foodborne and are caused by Campylobacter jejuni and C. coli. The animal reservoirs of these Campylobacter species, and the sources and routes of transmission, are described and discussed in this chapter. Most warm-blooded animals can be colonized by Campylobacter, but avian species, and in particular poultry, are preferred hosts. Much of the world's poultry production is colonized by Campylobacter. Source attribution studies estimate that 20-40% of cases are attributed to the handling and consumption of chicken meat, while up to 80% of cases are due to Campylobacter found in the chicken reservoir. The difference suggests that routes other than through the food chain, i.e., environmental contamination, are important. The epidemiology of infections in humans differs between industrialized and low-and middle-income countries. Thus, the most effective interventions would be targeted to primary production. To date, only improved biosecurity is available. If effectively implemented, strict biosecurity can reduce the number of Campylobacter-positive flocks, but implementation to this level has proved difficult for the poultry industry. Available interventions in chicken processing plants can substantially reduce Campylobacter numbers on carcasses and consequently reduce the risk to humans. Public health strategies therefore utilize control programs, which aim at reducing the level of Campylobacter by measures along the food chain. It is now recognized that commercially acceptable complementary interventions for primary production, such as vaccines and feed additives, are urgently needed. Once Campylobacter in poultry is controlled then other minor sources of Campylobacter including contaminated drinking water, direct contact with (pet) animals, and other food items (e.g., red meat and milk) can be addressed.