What other human diseases are known to have stemmed from avian flu?
Recent genetic studies show that the deadly 1918 “Spanish flu,” which circled the globe and killed an estimated 20 to 40 million people, developed in birds and was similar to the current strains of bird flu. Both viruses jumped directly from animals to humans. The 20th century’s other major pandemics, in 1957 and 1968, had different origins hybrid flu viruses. They were predominantly human viruses that acquired some genes from an avian source.