Etiology
The FIV is a retrovirus first isolated in 1986 and is in the same subfamily of viruses as human immune deficiency virus (HIV). There are criteria used for classification that clearly distinguish this virus from FeLV (feline leukemia), which is in a different subfamily altogether. FIV is a lentivirus that is isolated from peripheral blood leukocytes.

Epidemiology
Based on experimental studies, the major mode of transmission among cats appears to be inoculation by bite wounds. Research shows that neither close physical contact or sexual contact alone are effective modes of transmission. Other modes of transmission may be possible, but occur infrequently such as placental or colostral.

The highest risk cats are outdoor, free-roaming intact males with an infection rate three times higher than in females. Those cats infected with both FIV and FeLV tend to have a shorter life span, however combined infections are uncommon.

Clinical Findings
Three stages of FIV infection are thought to exist: initial acute stage, a prolonged asymptomatic latent period and a chronic terminal stage with clinical disease. Clinical disorders commonly seen include lymph node enlargement, fever, gingivitis and oral cavity disease, persistent upper respiratory infection, chronic wasting diseases, increased susceptibility to opportunistic infections, anemia, and neurologic symptoms.

Since FIV infection is a relatively newly recognized entity, the clinical picture of the stages is still incomplete. Symptoms related to the disease most commonly are seen involving the oral cavity, respiratory and intestinal tracts, skin, and lymph tissues.

Diagnosis
Diagnosis is done using serologic testing available by several readily available methods.

Therapy and Prevention
There is no known therapy to eliminate or cure this viral infection at this time. Antiviral agents are of questionable value due to lack of efficacy and toxic side effects. However, AZT may reduce viral replication and improve quality of life. Until alternative therapies are found, symptomatic therapies are all that is available for a symptomatic infected cat.

Long term prognosis for FIV infection is very poor. There is no vaccine currently available to protect against FIV, and since the transmission of the virus is not thoroughly understood, isolation of infected cats from uninfected cats is recommended.

There is no current evidence that FIV will infect people or any other nonfeline species. This family of viruses appears to be species-specific. However, immunocomprised patients are more likely to contract other diseases that potentially could have zoonotic potential such as fungal infections, parasites, protozoan infections, and others.