Many “bird flu” viruses occur naturally in wild birds, especially waterfowl and shorebirds and in domestic poultry.  The bird flu in the news is caused by the "H5N1" influenza virus and is different because it is more deadly than some other bird flu viruses.  Infected birds can spread the virus through bodily fluids to other birds.  It can also spread to other animals including pigs, cats and very rarely to humans.  Many people who catch bird flu live or work closely with infected birds.
There is currently no detected Avian Influenza activity in Marin County.

Most human cases to date have been located in Southeast Asia, and have resulted from contact with infected birds or surfaces contaminated with excretions from infected birds.
No sustained person-to-person transmission has been observed.