An adolescent presents with suspected infectious mononucleosis after recent exposure. Which test confirms EBV infection?

An adolescent presents with suspected infectious mononucleosis after recent exposure. Which test confirms EBV infection?

• A. CBC
• B. EBV-specific IgG antibody testing
• C. Heterophile antibody testing
• D. Throat culture

Answer: (B)

The key idea is using a test that directly shows the immune response to Epstein-Barr Virus. EBV-specific serology detects antibodies that target EBV antigens, providing direct evidence that the infection is due to EBV. This makes it the most definitive way to confirm EBV infection in suspected infectious mononucleosis. CBC can show nonspecific changes like elevated white cells or atypical lymphocytes, but those aren’t specific to EBV. A throat culture identifies bacteria that can cause sore throat, not EBV. Heterophile antibody testing (the Monospot test) can support the diagnosis of EBV mononucleosis, but it can be negative early in illness and is not as definitive as direct EBV-specific antibodies. Therefore, EBV-specific IgG antibody testing best confirms EBV infection (with the IgG pattern interpreted alongside clinical timing).

The key idea is using a test that directly shows the immune response to Epstein-Barr Virus. EBV-specific serology detects antibodies that target EBV antigens, providing direct evidence that the infection is due to EBV. This makes it the most definitive way to confirm EBV infection in suspected infectious mononucleosis.

CBC can show nonspecific changes like elevated white cells or atypical lymphocytes, but those aren’t specific to EBV. A throat culture identifies bacteria that can cause sore throat, not EBV. Heterophile antibody testing (the Monospot test) can support the diagnosis of EBV mononucleosis, but it can be negative early in illness and is not as definitive as direct EBV-specific antibodies. Therefore, EBV-specific IgG antibody testing best confirms EBV infection (with the IgG pattern interpreted alongside clinical timing).