New flu strain is a genetic mix

The WHO has confirmed at least some of the cases are a never-before-seen strain of influenza A virus, carrying the designation H1N1.

Although it's called swine flu, this new strain is not infecting pigs and has never been seen in pigs. The threat is person to person transmission.

It is genetically different from the fully human H1N1 seasonal influenza virus that has been circulating globally for the past few years. The new flu virus contains DNA typical to avian, swine and human viruses, including elements from European and Asian swine viruses.