What is the condition known as when a person has CD4 counts less than 200 cells/mm?

The correct response relates to the clinical definition of Acquired Immunodeficiency Syndrome (AIDS). When a person has a CD4 count of fewer than 200 cells/mm³, it indicates a significant reduction in the immune system's ability to function. CD4 cells, or T-helper cells, are crucial for coordinating the immune response against infections.

A CD4 count below this threshold is a hallmark of AIDS, which marks a progression from Human Immunodeficiency Virus (HIV) infection to a state where the immune system is severely compromised, making the individual more susceptible to opportunistic infections and certain cancers. This classification helps in determining treatment strategies and the urgency of medical interventions.

In contrast, simply having HIV does not imply that an individual has reached the AIDS stage, as many may have a higher CD4 count and remain asymptomatic or only mildly symptomatic. Chronic HIV would refer to a long-term infection but does not directly correlate with the immune deficiency indicated by a low CD4 count. AIDS-related complex typically refers to a stage where individuals may exhibit certain symptoms but are not classified as having AIDS. Thus, a CD4 count below 200 cells/mm³ definitively indicates a diagnosis of AIDS.