Hidden burden of primary Epstein–Barr virus (EBV) infection in pediatric febrile illness (0–12 years) – A retrospective study

Epstein-Barr virus (EBV) is an underrecognized cause of pediatric febrile illness due to its clinical overlap with other viral infections such as dengue and cytomegalovirus (CMV). This study aimed to determine the burden of primary EBV infection among febrile children and to assess the diagnostic limitations of using viral capsid antigen (VCA)-IgM alone for its detection. We retrospectively analyzed 245 stored pediatric sera submitted for dengue, chikungunya, or toxoplasma, rubella, CMV, and herpes simplex virus (TORCH) IgM testing. EBV-specific antibodies like VCA-IgM, VCA-IgG, and Epstein-Barr nuclear antigen (EBNA)-1 IgG were detected using commercial enzyme-linked immunosorbent assay (ELISA) kits. Primary EBV infection was defined as VCA-IgM positive with EBNA-1 IgG negative. Data were expressed as n (%) and compared using χ2 test. Primary EBV infection was detected in 9.8% (24/245) of cases, second only to dengue (42/245; 17.1%). Approximately one-third of VCA-IgM positive samples (12/36; 33%) represented false positives (FPs) due to cross-reactivity, primarily with dengue and CMV. VCA-IgM alone demonstrated 100% sensitivity but only 93.2% specificity. EBV infection was more common in infants, while dengue predominated in older children, though the difference was not statistically significant (P = 0.081). Primary EBV infection constitutes a hidden yet significant cause of pediatric febrile illness. Reliance on VCA-IgM alone may lead to diagnostic errors; hence, a complete EBV serologic panel is essential to improve diagnostic accuracy and avoid misclassification.