A Canadian teen who is in critical condition after contracting H5N1 bird flu was infected with a version of the virus that is different from the one circulating in U.S. cattle.
Researchers have identified new roles for a protein long known to protect against severe flu infection -- among them, raising the minimum number of viral particles needed to cause sickness.
Canadian officials have announced that a teenager in British Columbia has been hospitalized in critical condition with what is believed to be bird flu.