hMPV is circulating in the United States and is associated with respiratory tract disease in patients with respiratory illnesses not caused by respiratory syncytial virus, influenza, parainfluenza viruses, and adenovirus. Additional studies are required to define the epidemiology and the extent of disease in the general population caused by hMPV.

Human metapneumovirus (hMPV) is a recently discovered respiratory pathogen. We tested respiratory specimens for the presence of hMPV by reverse-transcription polymerase chain reaction. These specimens were obtained over a 1-year period from children aged <5 years and had negative results by the direct fluorescent antibody test for respiratory syncytial virus, influenza A and B, parainfluenza viruses 1-3, and adenovirus. Overall, 54 (8.1%) of 668 individuals tested positive for hMPV. During March and April of the study period, hMPV was detected in 17.6% and 25.0% of specimens tested, respectively. At least 2 distinct genotypes of hMPV circulated during the study period. Fever, tachypnea, cough, rhinorrhea, retractions of the chest wall, and wheezing were common findings. Of hMPV-positive children, 60.4% were aged <12 months. hMPV accounted for a small but significant proportion of respiratory-tract disease in infants and children.