Lorraine, I don't do rescue but I can tell you one thing that might help. It is always the youngest, oldest and weakest that get the sickest. Little Popeye is so small and young that he could appear very ill with the same virus that your other cats would simply be immune to. I hope you take comfort in what the vet said. The fact that Popeye is wanting to eat and has no fever is VERY good news! Being an airborne virus, it would probably be a good idea to keep Popeye away from the others for awhile and to wash your hands after handling him. Just the handwashing alone will go a long way to avoid the spread of the virus. ((((Lorraine))))