Infants who become infected with both respiratory syncytial virus and metapneumovirus are prone to develop severe inflammation of the small airways of the lung, called bronchiolitis, UK researchers report.

Respiratory syncytial virus is a well-known cause of respiratory illness in toddlers, while metapneumovirus - which was only identified in 2001- has recently been shown to cause similar problems. The researchers in the current study investigated the effect of simultaneous infection with these viruses.

They found that dual infection was strongly associated with “admission to the pediatric intensive care unit for mechanical ventilation,” Dr. Malcolm G. Semple of Royal Liverpool Children’s Hospital told AMN Health.

Bronchiolitis is endemic and peaks in the middle of winter in northern climates, Semple added. “The impact upon UK hospitals at the peak of the epidemic is such that in many pediatric hospitals additional wards are opened or routine surgery is postponed due to the influx of infants with bronchiolitis.”

As they report in the Journal of Infectious Diseases, Smple’s group studied children under 2 years of age who were hospitalized during the winter of 2001-2002. The team compared the rates of dual infection with respiratory syncytial virus and metapneumovirus among children who were moderately ill and were admitted to general pediatric wards, versus those with severe disease who had to be put on a respirator in an ICU.

Dual infection, the researchers found, conferred a 10-fold greater risk of requiring intensive care unit mechanical ventilation.

Given these findings, Semple said, future research into severe bronchiolitis must look into “multiple virus infection.”

SOURCE: Journal of Infectious Diseases, February 1, 2005.