Feline immunodeficiency virus (FIV) is a retrovirus, akin to the feline leukemia virus (FeLV) and the human immunodeficiency virus (HIV), that targets the feline immune system. This leaves cats vulnerable to a range of infections and cancers. Interestingly, about 2.5% of cats in the United States are FIV-positive. It’s important to note that FIV is species-specific and cannot be transmitted to mammals other than cats.
Transmission of FIV
Contrary to FeLV, FIV isn’t spread through casual contact. The primary mode of transmission is through bite wounds, where the virus, present in the saliva, enters the system. In utero transmission or via mother’s milk is exceptionally rare, typically only occurring if the queen contracts the virus during pregnancy or while nursing.
Prevalence of FIV
FIV is a global issue, affecting domestic cats and various wild felines, including snow leopards, lions, tigers, jaguars, Florida panthers, and bobcats. While the virus was first isolated in 1987, it has been around for much longer. It’s most prevalent in outdoor cats, with 1-2 percent of seemingly healthy cats in the U.S. being FIV-positive. Male cats are at a higher risk, as are those that roam freely, making bite wounds more likely.
Stages of FIV Infection
Similar to HIV in humans, FIV progresses through three stages. The initial stage presents with fever, swollen lymph nodes, and increased susceptibility to skin or intestinal infections, typically 4-6 weeks post-exposure. The second, latent stage, is asymptomatic and can last for years, during which the immune system may gradually deteriorate. The final stage mirrors AIDS in humans, often occurring in cats aged 5-12, where the immune system is severely compromised, leading to chronic opportunistic infections.
Clinical Signs of FIV
FIV-infected cats may exhibit general symptoms like lethargy, loss of appetite, fever, and swollen lymph nodes. Chronic oral infections are common, affecting about 50% of cats with FIV-related disease. Other issues include respiratory disease, eye problems, gastrointestinal disease, skin and ear infections, neurologic disease, lymphadenopathy, anemia, and neoplasia.
Diagnosis and Treatment
Diagnosing FIV involves testing for the cat’s antibodies against the virus, using an ELISA as a screening test and a Western Blot as a confirmatory test. PCR tests can also be used but are more expensive. The American Association of Feline Practitioners (AAFP) recommends testing all cats for FIV. Treatment focuses on managing the symptoms and preventing secondary infections. Antiviral medications used for HIV in humans are not routinely used for FIV, and there’s no vaccine currently recommended by the AAFP.
Prevention and Control
Controlling FIV relies on identifying and isolating positive cats, as they can transmit the virus to other cats through bite wounds. Keeping cats indoors or supervising their outdoor activities can reduce the risk of infection. While a vaccine exists, it’s not without controversy due to its impact on antibody testing and is not widely endorsed.
Human Health Risks
As retroviruses are species-specific, there’s no evidence that FIV can be transmitted to humans. However, humans should be cautious of secondary infections that FIV-infected cats may acquire, such as toxoplasmosis.