How The Avian Flu Is Transmitted. Runstadler says most flu viruses are. Through an intermediate host, such as a pig.

This lineage of bird flu originated around 1996 and was. The virus, which occurs naturally in wild birds, typically spreads through secretions — saliva, nasal discharge, and feces, in particular. The scientists in his lab study the ecology of influenza viruses in wild animal hosts, including birds, which are major reservoirs for influenza.