Stephanie I think it would have been too long between when that happened and when he got sick. I thought he got it from the Buddha Burger place, it fits in with the satire of the fast food restaurant, happy cows happy to be recycled...
This answer contains spoilers… (view spoiler)[Nope. Not just you. It's stated that Cameron's disease is "alien" and everything lines up: When he fell into the water and nearly drowned, when Dr. X did his experiment, when the dark energy entered the world... Some theories even suggest that he actually DID drown and everything that happened afterward was a dream. (hide spoiler)]
Vinjasnah A human version of mad cow disease called variant Creutzfeldt-Jakob disease (vCJD) is believed to be caused by eating beef products contaminated with central nervous system tissue, such as brain and spinal cord, from cattle infected with mad cow disease.
Keffrey Stellway I think he actually got it from some bad weed that he had smoked. I'm not sure if that's actually possible but he did smoke a lot of weed and although it didn't say specifically I think it's safe to assume that he didn't have the means to get any of the high quality stuff.