Report of a Myocarditis Outbreak among Pediatric Patients: Human Herpesvirus 7 as a Causative Agent?

Background: The etiology of myocarditis in children has not yet been completely elucidated. Objective: Medical records of eight pediatric patients diagnosed with acute myocarditis within a 41-day period in a small-town hospital were retrospectively analyzed. Methods: We examined antibody titers of adenovirus, Epstein-Barr virus, herpes simplex virus, respiratory syncytial virus, varicella-zoster virus and cytomegalovirus in peripheral blood. We used polymerase chain reaction (PCR) amplification to detect genetic sequences from Human herpesvirus (HHV) 7, HHV 6, enterovirus, measles or parvovirus in peripheral blood. Results: The causative agent was HHV 7 in four patients. HHV 7 sequences were detected through PCR in one patient with rapid deterioration. Of four patients with HHV 7, two presented with dilated cardiomyopathy. Conclusion: To our knowledge, this is the first report to suggest HHV 7 as a causative agent for acute myocarditis. We believe HHV 7 should be considered as a possible etiologic pathogen for patients with suspected myocarditis.