The West Nile Virus is a mosquito-borne virus that can cause encephalitis, the inflammation of the brain.  The virus was named after the West Nile region of Uganda, where it first appeared in 1937.

       West Nile is spread to humans by the bite of an infected mosquito.  Biting an infected bird is what infects the mosquitoes.  The virus is not spread person to person nor by bird to person.  The presence of West Nile in Canada was confirmed on August 22, 2001, when a bird was submitted out of Windsor, Ontario (Essex Region).

       There are many different theories to how this virus got into North America.  Some of these theories include the arrival of the virus through an infected bird, the importation of an infected mosquito or possibly an infected individual who had returned from a country where West Nile is circulating.  None of these theories have been confirmed.