Seasonality and clinical features of human metapneumovirus infection in children in Northern Alberta

Human metapneumovirus (hMPV) causes respiratory tract infections in all age groups. The characteristics of pediatric hMPV infection in Northern Alberta have not been studied. The objectives of this study were to determine the seasonality of pediatric hMPV infections over a 13-month period, the genetic relationship of hMPV isolates to hMPV detected in other parts of Canada, and the burden of illness and possible risk factors for pediatric hMPV hospitalization. Detection of hMPV by polymerase chain reaction was performed on nasopharyngeal specimens collected from outpatients and inpatients at the Stollery Children's Hospital in Edmonton, Alberta, November 12, 2002-December 31, 2003. Forty-two of 1,079 specimens were positive for hMPV (3.9%) from 41 patients (14 outpatients and 27 inpatients), with a peak incidence during January-April, but isolates were detected 10 months of the year. Co-infection was not detected in 39 specimens from which RSV had been detected. Two hMPV genetic clusters were detected, and the isolates were homologous to those of previous Canadian isolates. Four of the 14 outpatients had reactive airways disease. Possible risk factors in the 27 inpatients included prematurity (n = 8), congenital heart disease (n = 6), gastroesophageal reflux disease or aspiration (n = 6), global developmental delay (n = 5), and multiple congenital anomalies (n = 4). Risk factors for hospitalization appear to be similar to risk factors for respiratory syncytial virus hospitalization.