Feline lentiviruses

Feline Immunodeficiency Virus (FIV) is a retrovirus and lentivirus that affects domestic cats, causing an immunodeficiency syndrome similar to HIV in humans. It compromises the immune system, making cats more susceptible to secondary infections. Here's a breakdown of important information about FIV:

Transmission:

• Bite wounds are the most common mode of transmission, as the virus is primarily present in the saliva of infected cats. Fighting behavior, particularly among unneutered males, is a significant risk factor.
• FIV is not spread through casual contact, such as grooming or shared food and water bowls.
• FIV can also be transmitted from an infected mother cat to her kittens, but this is less common and can occur either in utero or through nursing.

Pathogenesis:

• FIV primarily infects T-lymphocytes (T-cells), specifically the CD4+ subset, which are crucial for coordinating immune responses.
• After infection, the virus goes through an initial acute phase with mild or unnoticed symptoms, followed by a latent or asymptomatic phase that can last for years.
• Over time, the virus weakens the immune system, eventually leading to a stage of immunodeficiency where the cat becomes susceptible to secondary infections, cancers, and other health problems.

Clinical Signs:

1. Acute phase: Cats may experience fever, lethargy, swollen lymph nodes, and loss of appetite. These symptoms often go unnoticed or are mild.
2. Asymptomatic phase: Cats may appear healthy for years while the virus slowly replicates and damages the immune system.
3. Immunodeficiency stage: As the immune system deteriorates, cats become vulnerable to infections (gingivitis, respiratory infections, skin infections), weight loss, diarrhea, and neurological disorders.

Diagnosis:

• Diagnosis is commonly done using antibody-based tests such as ELISA or rapid in-clinic tests. These tests detect the presence of antibodies to FIV in the blood.
• A Western blot test or PCR test may be used to confirm the diagnosis if initial results are ambiguous.
• Since kittens may acquire maternal antibodies from their mother without being infected, kittens under 6 months old that test positive should be retested later.

Control and Prevention:

• There is no cure for FIV, and infected cats remain lifelong carriers of the virus.
• Vaccination against FIV is available but has limited effectiveness due to the virus's genetic diversity and the difficulty in distinguishing vaccinated cats from infected ones in standard tests.
• Neutering cats can reduce aggressive behavior, particularly in males, which lowers the risk of fighting and transmission through bites.
• Keeping infected cats indoors helps prevent the spread of the virus to other cats and reduces the risk of secondary infections.

Disease Impact:

• FIV is not typically fatal on its own; many infected cats can live for years with proper care and management. However, the compromised immune system makes them prone to life-threatening infections and diseases.
• In some cases, FIV-positive cats can live a relatively normal lifespan if managed properly with regular veterinary care and prevention of secondary infections.

Immune Response and Viral Persistence:

• FIV, like other lentiviruses, causes a lifelong infection in cats.
• The virus's ability to evade the immune system by infecting immune cells leads to progressive immune system deterioration.
• While some cats can remain asymptomatic for years, their immune system eventually weakens, allowing opportunistic infections to take hold.

Management of Infected Cats:

• Good nutrition, stress reduction, and regular veterinary check-ups are key to maintaining the health of FIV-infected cats.
• Preventive measures such as vaccination against other common diseases and parasite control can help protect the weakened immune system.
• Secondary infections should be treated promptly, and any signs of illness in FIV-positive cats should be addressed immediately.

FIV’s long asymptomatic period and its primary transmission through bite wounds make it more manageable than some other viral infections, but the eventual immunodeficiency requires careful monitoring and prevention of secondary infections.