Feline infectious peritonitis is a viral disease of cats seen worldwide. Not all cats infected with the virus causing FIP will become ill, but cats who do develop signs of FIP will likely succumb to the disease eventually.t is thought that the mutation in the virus that leads to FIP is more common in cats with immature or weakened immune systems. The coronavirus is spread through direct contact via the nose and mouth with infected feces, so sharing litter boxes is a major route of transmission of coronavirus.
After infection, immunity to norovirus is usually incomplete and temporary, with one publication drawing the conclusion that protective immunity to the same strain of norovirus lasts for six months, but that all such immunity is gone after two years.
View larger image. Norovirus is a highly contagious virus. Anyone can get infected with norovirus and get sick. Also, you can get norovirus illness many times in your life. One reason for this is that there are many different types of noroviruses.he virus can stay in your stool for 2 weeks or more after you feel better. You are most contagious. 1  when you are sick with norovirus illness, and. 2  during the first few days after you recover from norovirus illness.