According to this article in Wired, epidemiologists have long anticipated that swine flu would evolve in factory pig farms and jump to humans. Factory farms serve as incubators of myriad diseases, where animals are packed so closely together they can't turn around and they stand in their own shit and urine 24 hours a day. Pigs are shipped across North America between birth and slaughter, spreading whatever viruses they happen to contain.
It was only a matter of time.
It doesn't take threats to humans to show that factory farming is morally wrong.
"The greatness of a nation and its moral progress can be judged by the way its animals are treated."
- Mahatma Gandhi