Yes, you read that right.
Out in the Borean Tundra, Unliving Swines near Warsong Hold will cast the debuff Swine Flu on you when you're fighting them. The pigs are dirty little creatures, and luckily anyone can cure the disease that has such an ability.
The Swine Flu disease itself is benign, however every time you attack something it has a chance at triggering an Outbreak. An Outbreak of Swine Flu will cause a fever that inflicts 120 nature damage every 2 seconds for 8 seconds total, and reduces movement speed to 70% of normal. Like Swine Flu, Outbreak is a disease that can be cured.
We should note that this isn't some joke recently put into the game. It's existed since Wrath of the Lich King released, so all the conspiracy theorists that are suggesting Blizzard manufactured the real swine flu in order to make more people stay home and play their game are clearly wrong. Clearly.
Oh noes! There's a knock at the door... I think Ghostcrawler and Belfaire are here with an offer I can't refuse.