What CD4 count range defines AIDS in adults?

What CD4 count range defines AIDS in adults?

• A. CD4 count below 200 cells/mm3 or AIDS-defining illness
• B. CD4 count below 500
• C. CD4 count above 200
• D. Any CD4 count with AIDS-defining illness

Answer: (A)

AIDS in adults is diagnosed when the immune system is severely weakened, defined either by a CD4 T-cell count below 200 cells per mm3 or by the presence of an AIDS‑defining illness. The CD4 threshold below 200 signals substantial immunosuppression and a high risk for opportunistic infections, which is why it’s used as a clear cutoff. But an AIDS‑defining illness itself also qualifies a diagnosis of AIDS, even if the CD4 count isn’t below that level, because those illnesses reflect that the immune system can no longer control certain infections or cancers. So the criterion can be met by either a very low CD4 count or by having an AIDS‑defining condition. This is why the statement combining CD4 <200 cells/mm3 or an AIDS‑defining illness best defines AIDS.

AIDS in adults is diagnosed when the immune system is severely weakened, defined either by a CD4 T-cell count below 200 cells per mm3 or by the presence of an AIDS‑defining illness. The CD4 threshold below 200 signals substantial immunosuppression and a high risk for opportunistic infections, which is why it’s used as a clear cutoff. But an AIDS‑defining illness itself also qualifies a diagnosis of AIDS, even if the CD4 count isn’t below that level, because those illnesses reflect that the immune system can no longer control certain infections or cancers. So the criterion can be met by either a very low CD4 count or by having an AIDS‑defining condition. This is why the statement combining CD4 <200 cells/mm3 or an AIDS‑defining illness best defines AIDS.