What criterion indicates that a client has progressed from HIV to acquired immunodeficiency syndrome (AIDS)?

The indication that a client has progressed from HIV to acquired immunodeficiency syndrome (AIDS) is primarily based on the CD4+ T lymphocyte level, specifically when it drops below 200 cells/µL. This critical threshold reflects a significant deterioration of the immune system, which is a defining characteristic of AIDS.

In individuals infected with HIV, the virus attacks and depletes CD4+ T cells, which are crucial for an effective immune response. When the CD4+ count falls below this level, the individual is at a much higher risk for opportunistic infections and other illnesses that can complicate and advance their health condition. This immunological impairment substantiates the progression from HIV infection to a diagnosis of AIDS, marking a crucial transition in the disease's severity and management.

Other criteria, such as the presence of opportunistic infections or significant body weight loss, can accompany a diagnosis of AIDS, but the definitive laboratory criterion remains the low CD4+ T lymphocyte count. In contrast, a positive HIV test for more than five years does not, by itself, confirm progression to AIDS since many individuals can live for years with HIV without progressing to AIDS.