How can food be contaminated?
Food may be contaminated with zoonotic pathogens in a number of ways. If an animal is affected by a particular disease, tissues from the animal, including its meat or milk, are a potential source of human infection if allowed to enter the food chain. More commonly, however, animals can be infected with zoonotic pathogens but show little or no signs of clinical disease. These ‘carrier’ animals are more difficult to detect either on the farm or at the slaughterhouse, so eradication is more of a problem. Many of these organisms live in the intestinal tract of healthy animals and can spread to humans through faecal contamination of the environment or of products such as milk during milking or eggs during laying. In addition, small amounts of intestinal contents may contaminate the carcass after slaughter and be present on raw meat. Cross-contamination of other foods can occur if they come into contact with a contaminated product either directly, during storage or preparation, or indirectly
