If several persons use the same computer within an office, the keyboard might become an easy source for disease transmission. If one of your office mates caught a cold or has herpes then you could easily overtake his disease.
This is explained by the fact that often we don't even leave our computer desks for taking meals. Lots of crumbs get on the keyboard which further stimulates bacteria.
Not obeying elementary hygiene is also one of the reasons for this. Moreover, it was surprisingly found out that a woman's workdesk contains much more bacteria than a man's.
