Feline Immunodeficiency Virus

Information/Facts
Infection
Clinical Signs
Diagnosis
Treatment
Prognosis
Prevention

  fivpic(e)          cathugs (i)          fivpic(e)

Information/Facts
Feline Immunodeficiency virus (FIV) is a retrovirus and belongs to the family Retroviridae, which also includes Feline Leukemia Virus (FeLV) and Human Immunodeficiency Virus (HIV).  FIV is a lentivirus - a virus that causes slowly developing disease.  (11)
 
FIV is an enveloped virus, possessing an RNA genome.  Retroviruses rely on the enzyme reverse transcriptase to perform the reverse transcription of its genome from RNA into DNA, which can then be integrated into the host's genome.  (12)

FIV occurs worldwide and its prevalence varies geographically. About 1.5-3% of cats are infected with FIV, and about 5% of FIV-positive cats also have FeLV.  FIV is not a zoonotic disease.  (13)

                                                                                                                                                    Return to top



Infection

FIV is transmitted primarily through deep, penetrating bite wounds. A mother cat may transmit the virus to her newborn kittens during gestation, passage through the birth canal, or nursing. FIV can also be transmitted through the transfusion of contaminated blood.

 
FIV prevalence is higher in older, male cats that spend a lot of time outdoors.  Aggressive male cats that roam and fight are more likely to become infected.  The average age of cats with FIV is 5 years at the time of diagnosis.

FIV attacks the immune system and as a result, the cat is unable to fight off various infections and cancers.  (13)

                                                                                                                                                                                                                                    Return to top

bushcat (i)

Clinical Signs
There are 3 described stages of FIV infection (13):

Stage 1
After infection, the virus spreads to nearby lymph nodes and eventually to all the lymph nodes.  This stage can last from days to months, during which there is a progressive decrease in the number of immune system cells in the body.  Usually there are no symptoms associated with this stage, however, some cats may develop a fever.

Stage 2
Stage 2 is an asymptomatic phase that may last for years.


Stage 3
Stage 3 is sometimes referred to as AIDS-related complex (ARC).  By this time, the immune system of the cat is very weak and the cat is susceptible to disease from bacteria, viruses, fungi or protozoans that would normally not affect healthy cats.  These secondary diseases are chronic, recurrent, tend to worsen over time, and are the major cause of death in these cats. Clinical signs associated with stage 2 may be poor coat condition, persistent fever, and loss of appetite.  There may also be signs associated with the nervous system, the eyes, the reproductive system and the upper respiratory tract.

                                                                                sickcat (x)
 
                                                                                                            Return to top
                                                                                                                                 
Diagnosis

Diagnosis of FIV is done by an ELISA (enzyme-linked immunosorbent assay) to detect for the presence of FIV antibodies.  All cats that test positive with the ELISA test should be confirmed by a different assay (usually a Western blot assay), as false positive results can occur. Sometimes the test result is inconclusive, in which case the cat should be tested again in 8 to 12 weeks.  There is a simple test that combines the FIV test with a FeLV (feline leukemia virus) test, since cats that are at risk for one are also at risk for the other.  (13)

fivtests (y)                            fivhisto (z) 

Pregnant cats that are infected with FIV can pass on their antibodies to the kittens through their milk.  This can cause kittens to have a positive result on an FIV test, even though they may not be infected with the virus. These antibodies should disappear within a few months. Therefore kittens under the age of 6 months that test positive should be retested when they are 8 to 12 months old.

 

If a cat is infected with FIV it may take 8 to 12 weeks before their body makes antibodies to the virus.  In this case, a test result may be negative even though the cat is infected. Therefore, FIV-negative cats that have been exposed to FIV-positive cats should be tested 8 to 12 weeks after exposure.  If the time of exposure is unknown, the cats should be retested every few weeks until an 8 to 12 week period has passed.

 

A blood test may show anemia or a very low level of white blood cells, but does not definitely confirm a positive result.  (13)

                                                                                                                                                                                                                                Return to top

Treatment
There is no cure for FIV.  As secondary infections can be fatal, it is recommended that these cats are kept away from other cats, kept indoors, and vaccinated against other viral diseases.  The use of an antiviral drug called Interferon, may help alleviate symptoms.  Certain medications such as systemic corticosteriods or griseofulvin that further suppress the immune system should be avoided.  Cats in stage 3 of the disease may require intravenous (IV) fluids therapy, blood transfusions, or high-calorie dietary supplements.  (13)
                                                                                                                                                                                                                                     
catwithiv (aa)
                                                                                                                                                                                                                                                       Return to top

Prognosis
The prognosis of cats infected with FIV is variable.  More than 50% of FIV-infected cats remain asymptomatic for years and about 20% of FIV-infected cats die within 2 years of diagnosis.  Cats in stage 3 of the disease usually die within a year.  (13)                                                                                                                                                                               Return to top

Prevention
The risk of contracting FIV can be reduced by neutering male cats, keeping cats indoors, and reporting stray cats to the local animal shelter or animal control agency.

Identification of positive cats is the only way FIV infection can be controlled.  Any FIV-positive cat, especially those in the terminal stages of disease, should be separated from non-infected cats.  (13)

Only a single vaccine (injectable) is currently available for prevention of FIV infection in the US and Canada.  It is a whole, inactivated virus with dual subtype.  This vaccine is licensed for healthy cats 8 weeks or older as an aid in the prevention of infection.  (13)


FIV vaccines should be considered as non-core, with use restricted to cats at high risk of infection (eg. outdoor cats that fight) and cats not infected with FIV living with FIV-infected cats.  It is important to note that vaccination induces production of antibodies indistinguishable from those developed in response to FIV infection and interferes with all antibody-based FIV diagnostic tests for at least a year following vaccination.  Permanent ID of vaccinated cats (i.e a microchip) will help clarify vaccination status but will not indicate that such cats are free of infection.  (3)
                                                                                                           catmicrochip (bb)
                                                                                                                                  
The following parameters are recommended (3):

 
Kittens less than 16 weeks of age:
- first vaccination at 8 weeks of age, subsequent doses 2-3 weeks apart
- 
when indicated, a single dose is given 1 year following the last dose of the initial series
- thereafter, annually in cats determined to have sustained risk of exposure
 
Kittens/cats older than 16 weeks of age:
- 3 doses required, each 2 - 3 weeks apart
- when indicated, a single dose is given 1 year following the last dose of the initial series
- thereafter, annually in cats determined to have sustained risk of exposure

Shelters and pregnant queens:
- vaccination not generally recommended
                                                                                                                                     Return to top


Home
         Glossary
References