Child at my camp has hand foot & mouth. should i be concerned about transmitting it to my 70 yr old father i visited in the hospital after a surgery?

Not particularly : The child is contagious thru oral secretions until their fever is gone plus a day or two, then they may continue to shed the germ in their stool. Normal hygiene practices help prevent spread of illness, so unless your father had direct contact or you had lapses in routine hand washing, spread is unlikely. Your father likely had it in childhood & has lifelong immunity anyway.

See note: No. Unless your father is immunocompromised in any way he should be resistant to contracting this virus. Adults are very unsusceptible to contracting this virus by children.

Pls see note: It is an illness caused by a virus, and the common cold is also caused by a number of possible viruses. If you are congested and ill, I would suggest using good hand washing, purell and staying around 6 feet away. They also may have masks for your use at the hospital.