To determine whether a kitten has cat plague, you can observe whether there are symptoms such as vomiting, diarrhea, poor energy, not eating or drinking, and blood in the stool. You can also use test strips to detect cat plague or send it to a pet hospital for examination. The results are a little more accurate. Feline distemper is highly contagious, so it is best to vaccinate kittens on time to avoid being infected with feline distemper. Once infected, treat it promptly to avoid life-threatening consequences.