Viruses comprising RNA cause a range of conditions in humans, from relatively mild (e.g. rhinoviruses causing the common cold) to very severe (e.g. Ebola, with a case fatality of around 60%). Influenza, polio, measles, hepatitis A and C and AIDS are all caused by RNA viruses. The Spanish Flu pandemic of 1918–19 and the Black Death of the 14th century in Europe have been the most devastating disease events in history, each causing an estimated 50 million fatalities (Scott & Duncan 2001, Benedictow 2005, Chandra & Kassens-Noor 2014). Some researchers regard the rapid spread and symptoms of the Black Death to be more indicative of an Ebola-type hemorrhagic RNA viral disease than the plague bacillus (Scott & Duncan 2001). In livestock, RNA virus diseases include bird flu, equine flu, swine fever and foot and mouth disease.