Not only do different types of visitors pose different levels of risk, but so do different areas of the farm and different groups of animals. The areas housing animals that are more susceptible to the introduction or potential transmission of infectious diseases are high-risk areas. The animals that are most susceptible to disease are young calves, especially prior to and just after weaning, cows in the few weeks before to few weeks after calving, and animals that are already sick. These animals are also most likely to shed microbial organisms, such as bacteria, viruses, or protozoa, that can infect other livestock. Some of these pathogens can cause illness in humans as well.

The areas with the highest risk in terms of biosecurity are those where animals meet either of the following conditions:

• Animals are more susceptible to disease, having an undeveloped or suppressed immune system.
• Animals are most likely to be shedding disease-causing organisms that can be transmitted to other animals or to people.

Photo: Julie Smith, DVM, Ph.D

High-risk areas on farms include the following:

• Birthing/calving pen
• Sick pen
• Close-up pen
• Fresh pen
• Housing for young stock less than 6 months of age