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.
Symptoms of norovirus illness usually begin about 24 to 48 hours after ingestion of the virus, but they can appear as early as 12 hours after exposure. Noroviruses are very contagious and can spread easily from person to person.ymptoms of norovirus illness usually begin about 24 to 48 hours after ingestion of the virus, but they can appear as early as 12 hours after exposure. Noroviruses are very contagious and can spread easily from person to person.