AIDS is defined by a CD4 count that drops below what threshold?

AIDS (Acquired Immunodeficiency Syndrome) is characterized by a CD4 cell count that falls below 200 cells/mm³. This threshold is significant because CD4 T cells are a type of white blood cell that play a crucial role in the immune system, and their depletion indicates severe immunocompromise. A CD4 count below 200/mm³ is associated with an increased risk of opportunistic infections and certain cancers, which are clinical indicators of AIDS.

When considering other counts such as 150, 100, or 250, these numbers do not define the onset of AIDS according to the established criteria set forth by the CDC. Specifically, counts below 200 are critical in categorizing the progression of HIV infection to AIDS. Thus, when the CD4 count dips below this level, it represents a point where the immune system is significantly impaired, leading to potential health complications.