From the Guidelines
A heterophile mono screen should be used as an initial diagnostic test for infectious mononucleosis, but it is essential to consider its limitations, including false-negative results, especially in children under 10 years and early in the course of illness, as noted in the 2013 IDSA and ASM guidelines 1. When interpreting the results of a heterophile mono screen, it is crucial to consider the clinical presentation and the potential for false-negative results, which occur in approximately 10% of patients, as stated in the study 1. Some key points to consider when using the heterophile mono screen include:
- The test detects heterophile antibodies that appear in the blood during EBV infection, typically between the sixth and tenth day following symptom onset 1.
- False-positive results may be found in patients with leukemia, pancreatic carcinoma, viral hepatitis, CMV infection, etc. 1.
- If the heterophile test is negative but clinical suspicion remains high, additional laboratory testing, such as EBV antibody testing for IgG and IgM to viral capsid antigen (VCA) and Epstein-Barr nuclear antigen (EBNA), may be considered to differentiate EBV infection from other causes of mononucleosis-like illness 1. The presence of VCA IgM (with or without VCA IgG) antibodies in the absence of antibodies to EBNA indicates recent primary infection with EBV, while the presence of EBNA antibodies indicates infection more than 6 weeks from the time of the sample and therefore not likely implicating EBV as a cause, as explained in the study 1. Given the potential limitations of the heterophile mono screen, it is essential to use it in conjunction with clinical judgment and other diagnostic tests to ensure accurate diagnosis and appropriate management of patients with suspected infectious mononucleosis.
From the Research
Heterophile Mono Screen
- The heterophile mono screen, also known as the monospot test, is a diagnostic tool used to detect infectious mononucleosis, a disease caused by the Epstein-Barr virus (EBV) 2, 3.
- The test detects the presence of heterophile antibodies in the blood, which are produced in response to EBV infection 4, 5.
- The sensitivity and specificity of the heterophile antibody test kits have been evaluated in several studies, with reported sensitivities ranging from 70-92% and specificities ranging from 96-100% 4.
- The monospot test is a rapid and widely used method for detecting serum heterophile antibodies, but it may not be positive in all cases of infectious mononucleosis, particularly in the early stages of the disease 2, 3.
- In cases where the monospot test is negative, but infectious mononucleosis is still suspected, serologic testing for antibodies to viral capsid antigens may be recommended to confirm the diagnosis 2, 6.
Diagnostic Tests
- Several commercial kits are available for the rapid diagnosis of infectious mononucleosis using purified heterophile antigen, including Monolatex, Mono-Latex, Mono-Lex, Mono-Plus, IM-Check, and Clearview IM 4.
- These kits have been evaluated for their performance and reliability, with some kits showing higher sensitivity and specificity than others 4.
- The choice of diagnostic test may depend on the clinical presentation and the availability of testing facilities 2, 3.
Clinical Significance
- Infectious mononucleosis is a common disease that can have significant clinical consequences, including fatigue, fever, sore throat, and lymphadenopathy 2, 6.
- The disease can also have long-term consequences, including an increased risk of certain cancers and autoimmune diseases 6.
- Accurate diagnosis and management of infectious mononucleosis are essential to prevent unnecessary investigations and treatments and to minimize complications 2, 3.