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Encephalitis in infectious mononucleosis: diagnostic considerations
Abstract:
Four atypical cases of presumed infectious mononucleosis (IM) encephalitis are presented. To establish an etiologic diagnosis, Paul-Bunnell-Davidsohn heterophil titers (PBD), antibody titers to the antigens of the Epstein-Barr virus (EBV), and oropharyngeal excretion of EBV were determined. Criteria for a primary EBV infection are (1) an antiviral capsid antigen titer of 1:160 or greater, (2) the presence of antibody to the diffuse component of the early antigen, (3) absence of antibody to the nuclear antigen, and (4) excretion of the virus from the oropharynx. Three of the four cases met these criteria; of the three, one did not have a positive heterophil titer. The fourth case turned out not to be IM; there was a positive PBD heterophil, but there was no evidence of primary EBV infection. Although the PBD heterophil is usually a reliable test to diagnosis IM, it is not always present in children, and it is sometimes nonspecifically elevated. Some EBV titers can be nonspecifically elevated as well; however, the above criteria are diagnostic of primary EBV infection.
Insights
Diagnosing infectious mononucleosis (IM) encephalitis requires specific Epstein-Barr virus (EBV) antibody testing, as the common heterophil antibody test can be unreliable, especially in children.
Area of Science:
- Virology
- Neurology
- Immunology
Background:
- Infectious mononucleosis (IM) encephalitis is a rare neurological complication.
- Accurate etiologic diagnosis is crucial for patient management.
Observation:
- Four atypical cases of presumed IM encephalitis were investigated.
- Diagnostic methods included Paul-Bunnell-Davidsohn (PBD) heterophil titers, Epstein-Barr virus (EBV) antibody titers, and oropharyngeal EBV excretion.
Findings:
- Established criteria for primary EBV infection: high antiviral capsid antigen titer, presence of early antigen antibody, absence of nuclear antigen antibody, and viral excretion.
- Three of four cases met primary EBV infection criteria; one lacked a positive heterophil titer.
- The fourth case had a positive PBD titer but no evidence of primary EBV infection, highlighting PBD test limitations.
Implications:
- The PBD heterophil test is not always reliable for IM diagnosis, particularly in children.
- Specific EBV antibody testing is essential for definitive diagnosis of primary EBV infection in encephalitis cases.
- These findings underscore the need for comprehensive diagnostic approaches beyond heterophil testing.