I don't buy that it's completely western. I was born and raised in Turkey, and the term for nerd there is "inek" which translates to "cow". The idea is that the person spends most of their time with their head buried in books, much like cows spend a lot of time with their heads buried in grass. Definitely not a positive term.
I'd say that "inek" firmly lies within what others would call "bookworm", having been called that. Maybe even implies a lot about schoolwork but not about much else. It implies that you don't have a personal life, because it is spent with schoolwork.
Nerd, on the other hand, conjures up a whole subculture that is quite different. The nerd not only is naturally good at schoolwork, but also has a personal life, but chooses to fill it with abnormal curiosa: Sci-fi, larping, reading, learning, etc.