http://www.slate.com/articles/health_and_science/science/2015/06/national_bio_and_agro_defense_facility_government_puts_pathogen_research.html

The United States eradicated foot-and-mouth disease from its borders in 1929. The virus, deadly to livestock, persists in more than 100 countries, though, and travels with ease. It is able to hitchhike on shoes, clothes, and tires. Airborne, it can travel almost 40 miles overland and almost 190 over open ocean. When the United Kingdom experienced a foot-and-mouth epidemic in 2001, more than 6 million animals had to be slaughtered to contain the virus’ spread. The economic fallout was devastating, and some farmers committed suicide (though of course it is difficult to establish cause and effect with suicide).