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.
On average, noroviruses cause 19 million to 21 million cases of acute gastroenteritis in the U.S. per year, according to the CDC. The norovirus was originally called the Norwalk virus, after the town of Norwalk, OH, where the first confirmed outbreak happened in 1972. Because there are many different types of noroviruses, exposure to one type may not protect you from other types.