sick when one flares up? I have two cats (one 5 yr old, another 8 mo just adopted) The new kitten has an Upper Respiratory infection, and the older cat caught it. They were both treated and are okay now, but the Vet told me the strain will lie dormant with them for the rest of their lives, and could flare up if the cat gets stressed or their immune system is low. Now my question is, even though both cats already have the strain, if one gets a flare up does that mean the other will get sick again too just by being around him?