FIP is a corona virus. All cats are exposed to the corona virus at one time or another. Depending on the immune system of your cat depends on the form it will take. Current information suggests that that FIP is an immune mediated disorder, meaning the disease is not caused from the unsuccessful efforts of the immune system to eliminate it. Leukemia often goes undetected because it can take different forms.
Some signs are emaciation, lack of immunity defenses, swelling of the lymph nodes, and anemia.
Infected animals must be kept away from healthy ones. There is no cure for this disease. Rabies is an old and familiar disease to everyone who has owned an animal. Today it is rare among domestic cats. Rabies is a highly contagious disease and can be spread animal to animal, also animal to humans.