The first stage is initial infection . The second stage is one of dormancy . The virus is inactive within the cat, so it causes no disease. If the cat is stressed during this stage, some virus shedding may occur. Otherwise, the cat is not contagious.
Some cats shed enough virus during the stressed period to be a threat to surrounding cats.
This stage may last a few weeks to several years. The third stage is clinical illness . It usually lasts a few weeks and terminates in death of the cat. As a rule, the cat is not contagious during this stage. Many treatments have been tried for cats with FIP, but none have been consistently successful.