Feline Leukemia and FIV
The Feline Leukemia Virus (FeLV) is a member of the Retroviridae family, and is somewhat related to the FIV virus, but is different in many ways. People often confuse the two. FeLV is sometimes called the "friendly cat disease" since, unlike FIV, FeLV can be spread by friendly contact. It is very contagious to cats, but humans cannot contract it. There is no cure for FeLV, but there is a vaccine to protect against it. The vaccine does not provide 100% protection, though, but has saved many, many cat lives.
FeLV is the most common cause of cancer in cats. It may cause various blood disorders, and it may lead to a state of immune deficiency that reduces the cat's ability to protect itself against other infections. The most common syndrome leading to death is a progressive anemia as the bone shuts down and loses its ability to produce red blood cells. Many infected cats die within 3 years of virus detection. About 70% of cats that are infected with FeLV develop immunity and are able to fight the virus before developing symptoms.
There are three main types of feline leukemia virus: FeLV-A, FeLV-B, and FeLV-C. FeLV-positive cats can be infected with one, two, or all three types. Type A is present in all cats with FeLV, and causes immune suppression. Type B is present in around half of all cats with FeLV, and causes tumors and other abnormal tissue growth. Type C occurs in about 1% of FeLV-infected cats and causes severe anemia.
The Leukemia virus is shed in high quantities in the saliva, nasal discharges, and in lower concentrations in urine and feces. It is also shed in the milk of an infected lactating cat. Cat-to-cat transfer of the virus can occur from a bite wound, but also during mutual grooming, and rarely through the shared use of litter boxes and feeding bowls. Nose to nose contact can spread it, as can the sneezing of the infected cat. Transmission can also take place from an infected mother cat to her kittens, either before they are born or while they are nursing.
Cats can be tested for FeLV in the vet's office with the results in minutes. All new cats brought into a home with existing cats need to be tested before they are allowed to mingle. Cats with FeLV should not mingle with cats who do not have it, since it can be easily spread.
FIV (Feline Immunodeficiency Virus) is similar to the virus that causes AIDS in humans. People cannot get FIV from cats. The effect of the FIV virus is a reduction in the cat’s immune system, making the cat more susceptible to infection and not well able to fight off infections. Therefore, a cat with FIV needs prompt vet attention at any signs of illness. Cats can be tested for FIV in the vet's office, with the results in minutes.
FIV is shed in the saliva of infected cats, and is most often spread by the infected cat biting non-infected cats during fights. On rare occasions, the offspring of an infected mother cat may become infected. The FIV virus cannot survive long outside the body, and is not spread by casual contact (this is opposite of the case with the Feline Leukemia Virus (FeLV) that FIV is often confused with).
Even though the virus is present in the saliva of an infected cat, it must be passed through the skin of another cat, as from a bite, in order it to be spread. So an infected cat sharing food bowls with non-infected cats is not known to spread the disease. You can keep cats with FIV with non-infected cats if they get along very well and don't fight. There could be a concern if a non-infected cat has open sores and the infected cats licks them. So one would want to keep the cat with any open wounds or sores from being groomed by a cat with FIV.
While there is no cure, well cared for cats who receive vet care can live many years with FIV. Cats with FIV should not be allowed to free roam outdoors and should be kept away from sick cats. This will minimize the chance of the cats with FIV contracting illnesses that it's body cannot fight off well, or at all. Disallowing cats with FIV to roam outdoors will also protect other roaming cats from possibly contracting FIV from your cat, should a fight occur.
FIV Vaccine not recommended: There is a vaccine for FIV, but it is not recommended in many areas since it does not cover all the strains of FIV. There are five FIV subtypes: A, B, C, D, and E. The vaccine it is reported to be 82% effective against only 2 of the subtypes, A and D. Subtype D is not known to be present in the United States. Subtype A is reportedly present only in the western United States and Hawaii. Subtype B is the most common in the eastern United States, but is not represented in the vaccine.
The most troubling thing about the vaccine is that a cat inoculated with FIV vaccine will test positive to the tests used to detect FIV infection in a cat. Then, if the cat is later tested for FIV, it cannot accurately be known if the cat is truly infected, or has been vaccinated, or is both infected and vaccinated.
Forum for owners of cats with FIV: http://www.catchat.org/forum.html