How can the bird flu transform into a flu that can infect humans?
a. Bird flu viruses only need to mutate a little bit in order to be able to infect humans.
b. Bird and human flu viruses can mix and match RNA chromosome strands in infected pig cells.
c. Bird flu viruses can steal glycoproteins from pigs, allowing them access to human cells.
d. The reverse transcriptase in influenza viruses can be activated when they change bird flu viruses into human flu viruses.
e. While bird flu doesn't infect healthy humans, it very easily can infect those who are already ill from another disease.