Skip to main content
Most King County offices will be closed on Monday, for Memorial Day.  
King County logo

West Nile virus (WNV) causes West Nile fever and West Nile meningitis, encephalitis and West Nile poliomyelitis. It can infect people, birds, mosquitoes, horses and other animals.

In Washington state, the virus was first found in horses and birds in 2002. The first human infection by WNV in Washington state occurred in 2006.