The eco-terrorist when he first learned about the cat virus was pissed off and made a new one. This one was similar to the cat one but it makes them into animals. However it was unstable like the cat scratch virus, so when he injected Jason when he passed him after picking him to test it out on. It's started affecting Jason like the cat scratch fever.
Jason headed straight up to his room once he got back home. Normally he would've gone down to his basement workshop, but he was extremely drained and in no mood for computer repair today. Stripping down to his boxers, he threw on his ratty old pajama shirt, carefully lowered himself into bed to avoid upsetting his stomach, pulled the comforter over himself, and went to sleep.
It was some hours later when he woke. He was nauseous again, and rushed to the upstairs bathroom, arriving just in time to heave his guts out into the toilet. He waited for a few minutes to make sure it was over, then rinsed out his mouth and headed back to his room,