OBJECTIVES. The purpose of this work was to assess the impact of recently described human metapneumovirus and human coronavirus NL63 compared with other respiratory viruses by using sensitive molecular techniques in a cohort of healthy preschool-aged children. We also aimed to assess the use of parent collection to obtain an adequate respiratory specimen from acutely unwell children in the community.
PATIENTS AND METHODS. The community epidemiology and burden of human metapneumovirus and other respiratory viruses (influenza A, influenza B, respiratory syncytial virus, parainfluenza viruses, adenoviruses, and picornaviruses) were examined in a cohort of 234 preschool-aged children from Melbourne, Australia, over a 12-month period by using polymerase chain reaction testing. Parents collected a daily symptom diary for the duration of the study and were taught to collect a combined nose-throat swab and complete an impact diary when the study child had an acute respiratory illness.
RESULTS. The average incidence of acute respiratory illness was 0.48 per child-month for the duration of the study, with a winter peak. Of 543 illnesses with ≥1 specimen returned, 33 were positive for human metapneumovirus (6.1%) and 18 for human coronavirus NL63 (3.3%). Of all of the viruses for which we tested, human metapneumovirus and human coronavirus NL63 were most strongly linked to child care attendance, occurring in 82% and 78% of infected children, respectively. Picornaviruses were the most commonly identified virus group (269 [49.5%]). Influenza virus and adenovirus illnesses had the greatest impact, with fever in more than three quarters and requiring, on average, >1 local doctor visit per illness.
CONCLUSIONS. Recently identified human metapneumovirus and human coronavirus NL63 are important pathogens in community-based illness in children, particularly in those who attend child care. Picornaviruses were detected in half of the nose-throat swabs collected during acute respiratory illness in children but resulted in milder illnesses; influenza and adenovirus caused the highest-impact illnesses. The use of parent-collected specimens should be considered for additional community-based epidemiologic studies and vaccine trials.