it's not very common.
you could contract it on non-genital body parts but really this whole scenario isn't worth worrying about.
How common is herpes witlow, and could a massage therapist with lesions infect a client's nongenital skin?
not likely the masseuse has herpes on their hands. if they do, even less likely that they'd be working when they had a flare up of it. It's bad for business if word gets out a sex worker has any sort of std or infection that is communicable and they are giving it to customers so they tend to be very good at not allowing workers to be working when something like that is going on.
herpes whitlow is only contagious when obvious lesions are present. otherwise the skin on the hands is too thick for the virus to penetrate to the surface without obvious lesions present.
grace