Coxsackievirus B3 sequences in the blood of a neonate with congenital myocarditis, plus serological evidence of maternal infection.

A fatal case of myocarditis in a neonate is described. The clinical features were evident at birth, and enteroviral RNA was detected in the blood of the baby on the day of birth and again 10 days later by a generic enterovirus nested reverse transcription-polymerase chain reaction (RT-PCR) assay. The enterovirus RNA was subsequently retested by a separate, newly developed nested RT-PCR assay yielding a PCR product within the VP1 coding region suitable for sequencing. Identical 239-base pair sequences were obtained from the RNA of the two blood samples and this sequence most closely resembled coxsackievirus B3 (94% identity). The baby's mother was pyrexial immediately postpartum and an early antenatal serum and a serum sample collected 10 days postpartum tested in parallel for enterovirus IgM antibody showed negative to strong-positive seroconversion. Infection of the mother was the likely primary event with in utero transfer of the virus to the fetus in the last few days of pregnancy. Neonatal blood is a valuable specimen for enterovirus diagnosis by RT-PCR. A newly developed nested RT-PCR assay was successful in typing the enterovirus from stored RNA extracted directly from the blood samples. Serology for enterovirus IgM antibody can be useful for convalescent diagnosis of enterovirus infection in the mother, especially with earlier serum for comparison.