Modern science has made some tremendous breakthroughs in the last century.  Diseases that used to plague livestock have now been brought under control or eradicated completely.  Only two infectious diseases can be considered completely eradicated: smallpox in humans in 1980, and rinderpest in ruminants in 2011.  When a disease occurs in a geographic region, animal health officials have three choices for response: eradication, elimination, or endemicity.