Since Crabs are little bugs that hang out on pubic hair the crabs can be transferred to another person even if the person is not sexually active.
The crabs can jump from one persons pubic hair to another persons body or get on bedding so if some has had crabs then their bed and sheets and blankets need to be cleaned really good before they're put in use again.
Crabs can also be in mustaches and armpits as well so it's not just pubic hair where crabs live.