Veterinary vaccines for animal and public health.

Vaccination is without doubt the most useful single measure available to prevent animal infectious diseases. The advantages of vaccination are numerous. It is the only available method to prevent, or sometimes cure, viral animal infections in the absence of broad spectrum antivirals and avoids the alternative of mass slaughtering of livestock. Antibiotic or anthelmintic resistance, and the problem of pharmaceutical residues, promote the use of vaccines rather than chemotherapy. Vaccines are environmentally friendly and increase animal welfare by preventing suffering from disease resulting from treatment for a cure which may result in antibiotic resistance and pharmaceutical residues in food. For the management of livestock health vaccines are the best tool to achieve sustainability. Veterinary vaccines cannot only be used to protect animal health but also human health from zoonotic infections through animal vaccination as exemplified by wildlife vaccination against rabies. In animal health the focus is now on animal infections rather than on animal diseases. Vaccines should be designed to prevent infection rather than to prevent clinical signs of disease and should, wherever possible, produce sterile immunity. Available technologies allow us to design "marker" vaccines together with their companion diagnostic tests which permit the distinction between vaccinated and infected animals even if the latter were previously vaccinated. Examples will be given of foot-and-mouth disease, classical swine fever, and herpesvirus infections of livestock such as pseudorabies or infectious bovine rhinotracheitis where carrier state or latency remain an issue after vaccination.