Basic epidemiology concerning transmission and frequency of infectious disease. Definition of prevalence, incidence, morbility, mortality and lethality. Definition and validation of diagnostic and screening tests. Biotechnological approach to the desing of molecular tools such as diagnostic tests and vaccines: individuation of usefull antigens; identification and cloning of specific genes of interest; expression of recombinant antigens and desing of a proper vaccine that allow discrimination between infected and vaccinated animals.