Parechovirus A infections in healthy Australian children during the first 2-years of life: a community-based longitudinal birth cohort study
Background: Hospital-based studies identify Parechovirus (PeV), primarily PeV-A3, as an important cause of severe infections in young children. However, few community-based studies have been published and the true PeV infection burden is unknown. We investigated PeV epidemiology in healthy children participating in a community-based, longitudinal birth cohort study.
Methods: Australian children (n=158) enrolled in the Observational Research in Childhood Infectious Diseases (ORChID) study were followed from birth until their second birthday. Weekly stool and nasal swabs, and daily symptom diaries, were collected. Swabs were tested for PeV by reverse-transcription polymerase chain reaction and genotypes determined by subgenomic sequencing. Incidence rate, infection characteristics, clinical associations, and virus co-detections were investigated.
Results: PeV was detected in 1,423/11,124 (12.8%) and 17/8,100 (0.2%) stool and nasal swabs, respectively. Major genotypes amongst the 306 infection episodes identified were PeV-A1 (47.9%), PeV-A6 (20.1%), and PeV-A3 (18.3%). The incidence rate was 144 episodes/100 child-years (95% confidence interval 128-160). First infections appeared at a median age of 8.0-months (interquartile range 6.0-11.7). Annual seasonal peaks changing from PeV-A1 to PeV-A3 were observed. Infection was positively associated with age ≥6-months, summer season, non-exclusive breastfeeding at age <3-months, and formal childcare attendance before age 12-months. Sole PeV infections were either asymptomatic (38.4%) or mild (32.7%), while co-detection with other viruses in stool swabs was common (64.4%).
Conclusions: In contrast with hospital-based studies, diverse, dynamically changing PeV genotypes circulate in the community causing mild or subclinical infections in children.