<human>:  Why is the Bird flu called Bird flu?
<bot>: The name Bird flu comes from the fact that the virus was first identified in birds. The H5N1 strain of the virus is known to infect birds, but not humans. In humans, the virus causes a disease called influenza, which is caused by the influenza virus. The virus that causes bird flu is different from the virus that causes the common cold, so the name is confusing.