Campylobacters occur widely as part of the intestinal flora of many warm-blooded animals and birds, particularly chickens and turkeys, and can be carried in animals that are used for food production and in domestic pets. In addition, they also occur in untreated water and raw milk. Evidence indicates that the most important risk factors for food-borne infection are consumption of undercooked poultry (particularly chicken), and other meat, unpasteurised or inadequately pasteurised milk and food that has been cross-contaminated.
Symptoms of infection in humans consist of diarrhoea, sometimes with bloodstained stools, which may last from 2-10 days. The illness is usually self-limiting, but can be severe.
Campylobacters do not grow in food at temperatures below 30OC so control measures should focus on the prevention of contamination and cross-contamination. Thus, experts around the world recognise that the application of HACCP to production, processing and distribution of poultry and other food products is important.
Consumers should be aware of the risk associated with consuming raw or undercooked food of animal origin. This risk can be avoided by consuming only thoroughly cooked meat/poultry, and only pasteurised milk; by obtaining water from approved sources; and by good hygiene in the kitchen. There is a low risk of human infection from close contact with companion dogs or cats, particularly if they suffer from diarrhoea.The Problem
Consequently, undercooked poultry, and to a lesser extent red meat and offal, are potential sources of campylobacter infections. Raw milk and poorly or untreated water supplies are also important potential sources of campylobacter infection. The main known facts about campylobacters, the disease and the preventive measures are given below.
The disease is usually self-limiting, so antibiotic treatment is only indicated in severe cases (Engberg et al, 2001, Guerrant et al, 2001). Complications such as septicaemia, reactive arthritis and Guillain-Barré syndrome (an ascending paralysis) may occur in a low proportion of cases.
In humans, transmission is predominantly via ingestion of contaminated food or water. The main route is thought to be eating undercooked poultry or food cross-contaminated by raw, infected food. Person to person transmission is known but thought to be rare. Household pets with diarrhoea have occasionally been shown to be the source of infection for humans.The Disease in Animals
Survival of Campylobacter Campylobacters do not survive well in food processing environments but they do survive for several months in frozen minced meat and poultry, although freezing kills a substantial proportion of the vegetative cells, and has been used to reduce numbers in raw poultry meat.
Campylobacters are heat-sensitive: for example a ten-fold reduction in count takes approximately 45 seconds at 60º C. Campylobacters are also very sensitive to drying. There is some evidence that campylobacters may survive in a viable but non-culturable form, but the role of this form in transmission is not known. Although campylobacters do not multiply in foods stored at temperatures below 30OC, they may survive for long periods. Survival is better at chill temperatures than it is at ambient temperatures. It is therefore vital to keep campylobacters out of all chilled foods. Irradiation readily destroys campylobacters and could provide a control measure for the future.Growth Characteristics of Campylobacters
Campylobacters appear to die rapidly on dry foods; this is in contrast to the prolonged survival of salmonellae in dried materials. The frequency of human carriers is low and long term carriers are uncommon (Milk may contain campylobacters as a consequence of faecal contamination on the farm. The organism will not survive correct pasteurisation procedures, and outbreaks of human infection associated with milk have generally involved consumption of unpasteurised (or inadequately pasteurised) milk or milk contaminated after pasteurisation. Post-pasteurisation contamination of milk has occurred from bird-pecked milk delivered door-to-door, but this is now rare, as this method of delivery diminishes. Other dairy products do not pose a threat because of the organisms’ low resistance to reduced pH or water activity.Control
Hygiene measures and biosecurity can be used to reduce the incidence of the organisms in/on poultry that is reared intensively (but not poultry reared outdoors) on the farm. Controls and decontamination during processing can reduce the numbers of campylobacters on carcasses, but at present raw poultry is likely to be contaminated with these bacteria.
Cross-contamination from raw poultry can occur in household kitchens and in commercial catering, and has been shown to be an important factor in about 30% of outbreaks (ILSI, 2006). Consumers are advised not to wash poultry carcasses or joints, as this process will spread contaminated water droplets in the kitchen. To minimise contamination of the kitchen environment and cross-contamination of foods, separate surfaces should be used for raw poultry and for other foods, work surfaces should be cleaned thoroughly, re-usable dishcloths should not be used, and people should wash utensils etc and wash their hands thoroughly and dry them thoroughly after handling raw meat or poultry.
Consumers should be aware of the risk of eating raw or under-cooked food of animal origin; they should be advised to avoid unpasteurised milk, to cook meat/poultry thoroughly and to obtain water only from approved sources. How to use good hygiene to prevent cross contamination from surfaces and utensils used in the preparation of raw poultry in the kitchen must also be highlighted through better education in safe food handling.
Contact with the faeces of diarrhoeal pets should be avoided and, if possible, animals should be kept out of the kitchen.
Susanne Surman-Lee | alfa
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