Which test confirms acute EBV infection or infectious mononucleosis?

• A. Heterophile antibody test (Monospot) or EBV serology
• B. Hepatitis B surface antigen
• C. CMV IgM
• D. HIV test

Answer: (A)

Acute EBV infection is confirmed by detecting antibodies produced in response to the virus, most commonly with the heterophile antibody test (Monospot), which is positive in many cases of classic infectious mononucleosis. This test serves as a practical screening tool because those heterophile antibodies arise during EBV infection and cause agglutination reactions that are easy to detect. If the Monospot is negative but clinical suspicion remains, EBV-specific serology helps confirm the diagnosis by showing antibodies to EBV antigens, especially VCA IgM, which appears in the acute phase, followed by VCA IgG and later EBNA antibodies as the infection evolves. It’s important to note that the Monospot can be falsely negative early in infection or in young children, so EBV-specific tests are used for confirmation in those cases. The other options point to different infections—hepatitis B, CMV, or HIV—and would not verify EBV infection.