Well, he has an extremely exaggerated version of OCD, but yes it is OCD.
There are few cases of people with OCD as extreme as him. most people only have one aspect of what he has, either germ problems, counting things etc.
I would say that he also has some sort of high definition autism as well, which would account for his excelent memory and his social problems.
Im very educated in this, having OCD myself, but no where near as bad as monk. I only really have the counting thing, but medication has calmed that down.
some peole with OCD think that if they dont do something, like put something down four times, then something really horrible will happe. and they cant control these thoughts.