Throughout the history of livestock production, infectious diseases have been a problem. One of the greatest impediments to the economics of livestock production today is the loss due to infectious disease. In addition to the current endemic diseases that plague livestock production, the emergence of new diseases or re-emergence of diseases to which populations are totally susceptible is especially worrisome. In the last 30 years, there have been approximately 30 newly emerged or re-emerged diseases, many of which can infect multiple species. There is clearly a need for novel, more effective control and treatment methods to ensure the viability of the livestock industry. Currently, the 3 available methods to control infectious disease include antimicrobials, vaccines, and immunomodulators. Recent advantages in our understanding of the interactions between disease causing organisms and the host, combined with techniques to identify protective antigens are providing novel approaches to developing more effective vaccines. Furthermore, by combining methods to stimulate the host’s own defences (innate immune responses), we can induce early protection from a broad-spectrum of infections, in the case of accidental introduction of a disease. These approaches should reduce animal suffering and add significant economic benefits to the producers, as well as improve food safety for the consumer