It doesn't look like it. He has his own desk and he seemed prolific enough that the hospital staff would use him as a consultant, and question him being missing, even if they're being quiet about it.

It would be difficult for a Taraxa to imitate a doctor for long term, however, given what was found in the sewers, and a new doctor might be questioned for odd behavior, but not an established one, who might just be taking ill.