Clinical manifestations and the natural history of HIV infection in adults.

The clinical expression of infection with the human immunodeficiency virus (HIV) appears increasingly complex. It includes manifestations due to opportunistic diseases, as well as illness directly caused by HIV itself. Neurologic disease may include involvement of the brain, spinal cord and peripheral nerves and is probably directly caused by HIV, as is lymphocytic interstitial pneumonia. The etiology of the chronic diarrhea and a papular pruritic skin eruption associated with HIV infection is unclear. Between 2% and 8% of HIV-infected persons progress to the acquired immunodeficiency syndrome (AIDS) per year, with no apparent decrease in the rate of disease progression over time. A chronically activated state secondary to chronic microbial antigenic exposure may increase both the susceptibility to HIV infection and development of disease. Increased HIV gene expression, followed by persistent antigenemia, appear to be triggering factors in clinical deterioration. The role, if any, of environmental and/or genetic cofactors remains unclear.