Some cats stay in this latent stage for only a few months, but for some it can last for years. Factors that influence the length of the asymptomatic stage include the pathogenicity of the infecting virus and FIV subtype (A–E), the age of the cat, and exposure to other pathogens. Finally, the cat progresses into the final stage (known as the feline acquired immune deficiency syndrome (FAIDS) stage), wherein the cat is extremely susceptible to secondary diseases that inevitably are the cause of death.[2]