Australis13 , 4 hours ago

Keep them apart for a week or so if you can to let any incubating infections show up. I recently had an upsetting experience with a family of stray kittens and their mother that my wife and I rescued, only to find out that they had feline parvovirus and had to be euthanised (whilst the kittens seemed fine when we caught them, the prognosis for kittens with parvo is horrendous; even the mother only had a 50/50 chance of survival). We kept them separate from our cats (and they are vaccinated anyway), but we still had to bleach the bathroom almost to oblivion to kill any trace of parvo. It was just a horrible situation.