My 11-year-old daughter has been asking for a hamster for her birthday. She wants a pet that is 'just hers' (the guinea pigs are 'everyone's pets,' according to her.) She's super-responsible for her age, and of course I would never take on a pet that I don't want to care for, so I would be checking up on the hamster's well-being as well. She wants to keep it in her room, so it would be living on a whole other floor than the pigs, who are downstairs in the family room and never go upstairs at all. My main concern is the possibility of passing illness, parasites, etc. If they are on different floors and I insist on handwashing after handling either animal, is there a risk of a hamster passing illness to the guinea pigs (or the other way around.) Other than the potential of residue on clothing or hands, there would be no contact between them.