Culture shock is a general term used for the disorientation or the confusion felt when a person goes to a hitherto unvisited country or place.
It could be because of the alien culture, food habits, lack of friends, behaviour of the people , etiquette or anything that prevents one to adjust to a new place. If the new culture is conspicuously different from ones own, then the disorientation is more.
It can be more pronounced when one is planning a long stay.

Please refer to Reverse Culture Shock also.