Avian flu typically spreads between wild and domestic birds but can spread to other animals and people. There have now been more than 40 confirmed human cases in the United States, according to the Centre for Disease Control,

People have been hearing a lot about H5N1 bird flu — or highly pathogenic avian influenza — since a B.C. teen became the first human to get the virus in Canada and is in hospital.

A teenager in British Columbia was hospitalized in critical condition with the disease, and officials were working to find out how the person was exposed to the virus.