When I watched this movie, I got the impression that Ted was merely approaching it in a scientific, biology based manner despite the werewolf curse being supernatural in nature. By looking at it as a true disease, it also allows him to hope there's a viable cure instead of sinking into despair right away.

It's vague enough so the viewer can decide the truth on their own, as the focus of the movie isn't on this topic. It's just an extra detail that's toyed with off to the side.

But also might explain no silver bullet or full moon he was changing at any moon which would implies there's some biological process at work.