HIV infection is a common acquired immunodeficiency. Which combination of tests is commonly used for diagnosis and staging?

• A. HIV infection; diagnosed by HIV antigen/antibody tests, RNA viral load, and CD4+ T cell counts
• B. Malaria; diagnosed by blood smear
• C. Tuberculosis; diagnosed by sputum smear
• D. Hepatitis C; diagnosed by ALT levels

Answer: (A)

Diagnosis and staging of HIV rely on a layered testing approach that confirms infection, measures viral replication, and assesses immune status. HIV antigen/antibody combination tests (often fourth-generation) detect both p24 antigen and HIV antibodies, enabling earlier detection than antibody tests alone. If infection is confirmed, measuring HIV RNA (viral load) shows how actively the virus is replicating and helps monitor treatment response, while CD4+ T cell counts indicate the current level of immune function and are used to stage disease progression. This combination best fits the goal of diagnosing HIV and assessing its stage. Other listed diseases have different screening and diagnostic methods (for example, malaria, TB, or hepatitis C), so they do not address HIV diagnosis and staging.