Feline leukemia virus is a retrovirus that infects cats. FeLV can be transmitted from infected cats when the transfer of saliva or nasal secretions is involved.
A cat's viral load can change over time, and the form of feline leukemia virus infection can affect lifespan. In general, adult cats progressively infected with FeLV have a life expectancy of 2-6 years after diagnosis.

Such cats include cats living with infected cats or with cats of unknown infection status, cats allowed outdoors unsupervised where they may be bitten by an infected cat, and kittens born to infected mothers. Though any cat exposed to the virus can develop an FeLV infection, kittens are...

Furthermore, visual representations like the one above help us fully grasp the concept of Male Cat Leukemia Virus Oncology.
In humans, leukemia is a type of cancer of the blood and bone marrow, but cat leukemia is actually a virus. However, it can cause serious health issues and lead to cancer in cats. Feline leukemia is highly contagious and one of the most common infectious diseases in cats.

Only about 3% of cats in single-cat households have the virus, but for cats that spend time outdoors, the rate is much higher. Still, the prevalence of FeLV has decreased over the last 25 years because of vaccines and reliable tests. Symptoms of Feline Leukemia Virus.
ABCD cats & vets: GUIDELINE for Feline Leukaemia Virus Infection.
A 13-year-old feline leukemia virus-negative cat was diagnosed with acute lymphoid B-cell aleukemic leukemia. The diagnosis was based on the combination of pancytopenia, large and atypical round cells present on liver and splenic cytology...