In 2001, a new respiratory pathogen was discovered - the human metapneumovirus. Human metapneumovirus is closely related to respiratory syncytial virus, both virologically and clinically, however, metapneumovirus causes slightly less serious illnesses than respiratory syncytial virus. A recent study has shown that most people have antibodies to pneumoviruses and that metapneumovirus has been a human pathogen for about 50 years.

In a long-term prospective study at Vanderbilt University (Nashville, USA), researchers confirm the etiological significance of this pathogen in the development of infectious respiratory diseases in previously healthy children.

During the study, 2009 children and adolescents were observed and examined during the 25-year period of the study (from 1976 to 2001). The virus isolation and PCR method was used to identify virus RNA in frozen nasal washes.

A viral etiology other than metapneumovirus was found in 279 of the 678 cases of lower respiratory tract infection (41%) in 463 children. In 408 cases of disease in 321 children, the pathogen was not identified and, in this group of patients, in 248 cases, nasal smear samples were obtained. 49 of 248 samples (20%) contained RNA from human metapneumovirus or a live virus.

About 80% of diseases caused by metapneumovirus occurred during the fall-winter increase in the incidence of influenza and SARS (December to April). The average age of children infected with metapneumovirus was 11.6 months; the boy / girl ratio was 1.8: 1. Among children infected with metapneumovirus, cough was observed in 90% of cases, fever - in 52%, wheezing - in 22%, otitis acute mean - in 51%, pharyngitis - in 39%. Final diagnoses included bronchiolitis (59%), croup (18%), exacerbation of bronchial asthma (14%) and pneumonia (8%). The virus was detected in 15% of samples from 261 children with upper respiratory tract infections, and only 1 in 86 samples without symptoms of disease.

Based on these data, the authors argue that approximately 12% of all lower respiratory infections in this patient cohort are most likely caused by a metapneumovirus.

Thus, the human metapneumovirus is one of the main causes of respiratory tract infections in children in the first year of life, causing diseases that are symptomatic similar to infections that occur when they are infected with respiratory syncytial virus.