Home » Pet Health » Feline Infections and Viruses » Feline Immunodeficiency Virus and Transmission


Feline immunodeficiency virus (FIV) is one of the most common causes of infectious diseases in cats globally. FIV is a retrovirus. A retrovirus is a virus that enters the body, attaches itself to the host immune cells, and inserts its genetic material into the cell. FIV is closely related to the human immunodeficiency virus (HIV) that causes acquired immune deficiency syndrome (AIDS). In infected cats, FIV suppresses the immune system and impairs its ability to fight infections, leaving cats vulnerable to various diseases. A variety of different organisms may cause these diseases. Many of these organisms, including fungi, bacteria, and viruses, are harmless in healthy cats but can be dangerous for FIV-positive felines. FIV-infected cats are also at an increased risk of cancer and blood-related disorders. Cats with FIV may seem healthy for many years, but there is a likely chance their health will decline over the years as the disease progresses.

FIV prevalence

The number of cats infected with FIV varies by geographic location. In North America, reports indicate that 2.5% of cats are infected, while 9.5% of cats are FIV-positive in Ankara, Turkey. Furthermore, up to 31.2% of cats in Malaysia have been reported as FIV-positive. Outdoor cats have a much higher chance of contracting FIV. As North America has a high prevalence of indoor, domestic cats compared to different parts of the world, this likely accounts for geographical differences in infection rates.

How is FIV transmitted?

FIV is present in the saliva and blood of an infected cat. Therefore, the most common way to transmit is through a bite. FIV can also spread through contact with FIV-positive blood. Outdoor cats usually contact a higher number of cats than domestic pets, heightening their chances of becoming infected. Generally, male cats are more prone to infection due to their propensity to fight. Additionally, most cats are diagnosed with FIV when they are young, at approximately 1-2 years old, because younger cats tend to engage in more territorial fighting.

Although rare, kittens can become infected with FIV through their FIV-positive mother. Kittens have a higher chance of contracting FIV if the mother was bitten and infected at the time of mating. In this case, the mother will have a high viral load when giving birth and therefore have an increased chance of infecting the kittens. If the FIV-positive mother becomes infected before mating, however, there is a low chance the mother will pass the virus on to her kittens.

Unlike HIV, FIV rarely spreads through sexual contact. Furthermore, social grooming, sharing food bowls, and snuggling are unlikely to cause FIV transmission. FIV infection is species-specific which means cats cannot transmit it to humans.

Can FIV be prevented?

The best way to prevent FIV infection is by limiting exposure to infected cats. Outdoor cats are more likely to contract FIV than cats that stay indoors. Also, male cats are more prone to infection, given their tendency to roam and fight. Spaying and neutering of FIV-infected cats can help reduce a cat’s fighting tendencies and subsequent spread of disease. Since FIV cannot survive outside of the host, frequent disinfection and proper hygiene will reduce the spread of infection.

To prevent infection, make sure any pets your cat spends time with are FIV-negative. If you are adopting a new cat, test for FIV before introduction to the household.

There are currently no FIV vaccines in the United States or Canada to protect cats from infection.

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Last Updated: August 21, 2022

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