Sepsis-like Disease in Infants Due to Human Parechovirus Type 3 During an Outbreak in Australia

Background. Infections with human parechoviruses (HPeVs) are associated with a wide range of clinical presentations in children, ranging from mild or asymptomatic infections to severe sepsis-like presentations or meningoencephalitis. Methods. We reviewed medical records of infants admitted to 5 hospitals in New South Wales, Australia, during an outbreak of HPeV-3 infection. Data were collected on clinical presentation, laboratory markers, and outcome of infants with HPeV infection confirmed by reverse transcription polymerase chain reaction. Results. We identified 118 infected infants. Most presented with an acute sepsis-like syndrome with high fever, tachycardia, poor perfusion, and severe irritability. Other common features were erythrodermic rash, abdominal distension, edema, and hepatitis. The age range of infants was 4 days to 9.5 months; 75% were <2 months old, including all but 1 of the 30 infants (25%) admitted to intensive care units (ICUs), who as a group, were significantly younger than infants not admitted to ICUs. Only 4% of evaluable cerebrospinal fluid samples had pleocytosis, but HPeV was detected in 95%. Brain magnetic resonance imaging on a small number of children demonstrated white matter changes and diffusion restriction. Sequencing of the VP1 gene confirmed HPeV-3 in all samples tested. All children recovered without ongoing complications at last follow-up. Conclusions. We report the largest series of HPeV-3 infection in infants, and the first outbreak in Australia. Infants presented with a severe sepsis-like syndrome with a high rate of ICU admissions, but all recovered from the acute infection without complications. Long-term sequelae are unknown.