The recent appearance of the H5N1 bird flu in pigs does raise viral reassortment concerns. Here's what we know about this highly pathogenic avian influenza virus so far.

H5 bird flu, a type of avian influenza, has infected dozens of people in the U.S., and spread to seven states and Canada this year.As concern grows over whether it could lead to another pandemic or lockdown,

Human cases in the US are on the rise and the virus is turning up in cows and dairy products. Luckily, we have some vaccines ready to go if needed.

In the 2009 swine flu pandemic, multiple reassortment events in pigs and birds led to the novel H1N1 virus strain, which led to 60 million cases and 12,000 deaths in the U.S. in its first year of circulating, per the CDC .

The developing avian influenza panzootic and the growing possibility of a pandemic bring to the fore the existential questions for humanity of climate change and the destruction of public health, both of which must be stopped in order to control the growing threats.

The H5N1 virus that infected a Canadian teen appears not to have spread, but it shows signs of mutation that makes flu virologists nervous.