Herd-based Testing for Infectious Diseases

Abstract

The objective of herd-based testing for specific infectious diseases is to monitor for either the presence of the disease in the herd or the presence of individual animals in the herd with the disease. The information can be used to develop the appropriate control measures to prevent a disease from entering into a herd or to control a disease in the herd by reducing or eliminating the disease from the herd. The herd-based testing is part of the program for control of specific diseases within the herd and needs fit within the goals and objectives of the herd for the overall control of infectious diseases. The needs of herds for herd-based testing and types of herd-based tests used will vary depending upon whether the herd is a "closed-herd," producing its own replacements internally, or purchasing replacement animals from outside sources, whether the herd has had on-going control program and has reduced the prevalence of disease to low levels and needs to now monitor for the presence of the disease. The specific herd-based tests need to be selected based on the goals for the individual herd. For example, the objective of testing for Leptospira hardjobovis is to determine if the disease is present in the herd whereas the objective of tests for BVD may be to identify individual animals that are persistently infected.