Following infection with the virus the disease progression varies widely among individuals depending on host susceptibility, genetics, immune function, health care, co-infections and the viral genetic variability.
Some patients progress rapidly (4 yrs) to AIDS following primary HIV infection and are called as Rapid Progressors. Some studies report that disease progression is more rapid in Africa.
On the other hand Long Term Non-Progressors show no sign of the disease for over 12 years and remain asymptomatic. The common reasons could be that the virus that infects the individual could be replicating inefficiently or that the patient has a strong immune system.
Those whose clinical and laboratory parameters remain stable over long periods of time but experience signs of progression are termed as Long Term Survivors (LTS).
The Centers for Disease Control and Prevention (CDC) has released findings that genes influence susceptibility to HIV infection and progression to AIDS. HIV enters cells through an interaction with both CD4 and a chemokine receptor (CCR5 and CCR2). It was found that it is possible that a person with the CCR5-Δ32 receptor gene will not be infected with HIV.