From the Guidelines
Mononucleosis screening should start with a heterophile antibody test, followed by specific Epstein-Barr virus (EBV) antibody testing if the initial test is negative or inconclusive, as recommended by the Infectious Diseases Society of America (IDSA) and the American Society for Microbiology (ASM) in 2013 1. When evaluating patients for mononucleosis, it is essential to consider the clinical presentation, including symptoms such as fever, pharyngitis, and lymphadenopathy, particularly in adolescents and young adults.
- The heterophile antibody test, also known as the monospot test, is a rapid and widely available screening tool that detects heterophile antibodies produced during EBV infection 1.
- However, this test has limitations, including a sensitivity of around 90% and potential false-negative results, especially in children under 10 years old and in the first week of illness 1.
- Specific EBV antibody testing, including viral capsid antigen (VCA) IgM and IgG, early antigen (EA), and Epstein-Barr nuclear antigen (EBNA), can provide a more definitive diagnosis and help differentiate EBV infection from other causes of mononucleosis-like illnesses, such as cytomegalovirus (CMV) or toxoplasmosis 1.
- A complete blood count (CBC) with differential can also be valuable in supporting the diagnosis, as it often shows lymphocytosis with atypical lymphocytes in patients with mononucleosis 1. The goal of screening is to accurately diagnose mononucleosis and distinguish it from other conditions that may require different management, such as streptococcal pharyngitis, to avoid unnecessary antibiotic use and potential complications, such as rash development with amoxicillin 1.
From the Research
Mononucleosis Screening
- Mononucleosis, caused by Epstein-Barr virus (EBV), is characterized by a triad of fever, tonsillar pharyngitis, and lymphadenopathy 2.
- The classic test for infectious mononucleosis is the demonstration of heterophile antibodies, with the monospot test being the most widely used method to detect serum heterophile antibodies 2.
- When confirmation of the diagnosis is required, serologic testing for antibodies to viral capsid antigens is recommended 2, 3.
- A complete blood count with differential can also be used to assess for greater than 40% lymphocytes and greater than 10% atypical lymphocytes 3.
Diagnostic Challenges
- Atypical cases of mononucleosis can present challenges for diagnosis, and distinguishing bacterial tonsillitis infections from early acute mononucleosis can be difficult 4.
- The heterophile antibody test has a sensitivity of 87% and specificity of 91%, but can have a false-negative result in children younger than five years and in adults during the first week of illness 3.
- The presence of elevated liver enzymes can increase clinical suspicion for infectious mononucleosis in the setting of a negative heterophile antibody test result 3.
Screening Recommendations
- Cost-effective, efficient initial laboratory testing for acute infectious mononucleosis includes complete blood count with differential and a rapid heterophile antibody test 3.
- Epstein-Barr viral capsid antigen-antibody testing is more sensitive and specific, but more expensive and takes longer to process than the rapid heterophile antibody test 3.
- Current guidelines recommend that patients with infectious mononucleosis not participate in athletic activity for three weeks from onset of symptoms 3, 5.