aids is the final stage of hiv infection. when the immune system cd4 cells drop to a very low level a person's ability to fight infection is lost. in addition there are several conditions that occur in people with hiv infection with this degree of immune system failure; these are called aids-defining illnesses. according to the cdc 1 051 875 people in the u. s. have been diagnosed with aids since the disease was first diagnosed in 1981. they also estimate that 583 298 have died from the disease in the u. s.
what is aids?