Severe human parechovirus type 3 myocarditis and encephalitis in an adolescent with hypogammaglobulinemia

Human parechovirus (HPeV) belongs to the Picornaviridae family of RNA viruses. HPeV infections can be asymptomatic, lead to mild respiratory and/or gastrointestinal symptoms, or less frequently cause severe diseases such as sepsis, meningitis, encephalitis, and myocarditis. Severe neurological HPeV infections occur most commonly in infants and neonates. There are currently 16 recognized types of HPeV. HPeV type 3 (HPeV3) has been the predominant type associated with severe central nervous system disease in neonates and newborns since its discovery in 1999. Although HPeV-related infections have been reported in adults, symptomatic HPeV3 infections in adolescents and adults are uncommon. A case of severe HPeV3 myocarditis and encephalitis in an adolescent is described.