Historically, interest in virology developed because these tiny microbes caused significant human and veterinary disease. One picornavirus, foot-and-mouth disease virus, was the first animal disease virus discovered; it was identified by Friedrich Loeffler and Paul Frosch in 1898 as a filterable, infectious agent that caused the dreaded foot-and-mouth disease. The discovery of poliovirus as the etiologic agent of poliomyelitis was reported 11 years later by Karl Landsteiner and Edwin Popper...
Source: wiktionary