Three times we've visited the grandparents and twice our daughter has come back with a cold. What should we do in the future?

My wife and I had a baby in early spring on 2017 and we emigrated in the summer. We live close to her side of the family but my side are back over there, as it were. Both sides of the family have close bonds and we have no issues there, for which we're very fortunate. We're always offered help and on the rare occasion that both sides get together we all have a wonderful time.We've been over to visit my family three times since the birth: the first time after a few weeks, the second at the 3 month stage and the third most recently for Christmas. Both the first time (thanks to my sister) and the third time (thanks to my brother or his daughter) our daughter has come back with a cold. We're getting annoyed now because although colds are a mild infection for us, they're a real pain for our daughter (and any other baby, frankly). It means several nights of crap sleep for all and a very cranky kid with interupted sleeping patterns. But how on earth can we avoid this in the future?I should mention that I am an epidemiologist and I conduct research on vaccines for infectious diseases in children and adults...I know there's nothing we can do to prevent the little'un from getting a cold other than to avoid contact with an infected person or infected surfaces. I'm not looking for people's home remedies on preventing/curing, more I'm looking for advice on how to approach the issue if in a few months time we get the call a day or so before flight departure and are told "XYZ has a cold". If we fly then we risk another cold, so should we cancel? Should we ask the infected person to avoid us for the weekend? How would that work when we're all under the same roof?If we're expecting visitors from my wife's side of the family then it's really easy to ask them to delay their visit by a week if they're unwell because they live 20 minutes away. It's not so easy to ask my parents or siblings to avoid coming close to my daughter, though, if they haven't seen her for several months and we stay in their house whilst we visit. Babies will get sick often - they are nature's perfect disease-acquiring and disease-spreading vectors, but our (for want of a better phrase) bad luck is starting to annoy us now. We'll soon be planning the next visit in spring.EDIT: spelling via /r/Parenting http://ift.tt/2ldK5Qh