Credit: Gene Page/AMC Photo: Daryl Covers His Face With a Bandana in The Walking Dead Season 4, Episode 2: “Infected”

Update (10/15/13): In an interview with Vulture, Robert Kirkman likened this illness to something like the Spanish Flu. In other words, this isn't some new, devastating disease. He explained, "It’s important to know that this is really just some form of the Spanish Flu. It’s something that exists in our everyday world now; it’s a time where there is no modern medicine. Scott Gimple, the new showrunner, really wanted to explore that new possibility of the simple things, the really little things, coming to devastate these people. That’s what we’re going to explore."

Spoiler alert:
If you haven’t seen the Season 4 premiere of The Walking Dead, then avert your eyes!

On tonight’s TWD opener, newcomer Patrick died as he prepared to take a shower, but in a surprising twist his death had nothing to do with a walker. Instead, Patrick complained he wasn’t feeling well before he had a coughing fit and collapsed.Thanks to a closeup on his bloodshot eyes, we know Patrick turned even though he was never bitten.

So, what is this mystery illness that took Pat’s life?

While it could just be a nasty case of the flu or something along those lines, given the fact that Season 4, Episode 2 is called “Infected”, it looks like we could have an epidemic on our hands.

Some have speculated that Rick’s pigs are the source of this new sickness, and we have to admit that theory is pretty intriguing. Livestock can certainly transmit diseases (we’ve all seen Contagion, right?) and it would be something totally unexpected.

What do you think this new sickness is? Tell us your thoughts and theories below!