Swedish researchers said they had identified a previously unknown virus that may cause many cases of serious respiratory infections in children.
They named the virus human bocavirus and suggested the researchers start a systematic search for all the viruses that cause respiratory infections.
The report, published in this week’s issue of the Proceedings of the National Academy of Sciences, underlines how little doctors know about the sources of most respiratory infections.
A separate team of California researchers found they could only identify about 40 percent of viruses infecting patients, and both teams said rapid testing for viruses would be useful in diagnosing and treating respiratory illnesses.
Health experts say this step was particularly important because there are fears that influenza, in particular avian influenza, could cause a global pandemic.
Being able to test quickly to find out what is making someone sick can mean the difference between life and death because antiviral medications must be given early on to prevent serious illness in the case of influenza.
In their sample of 540 children in a pediatric hospital ward, the new bocavirus was responsible for 17 of the cases, the Swedish researchers found.
'A leading cause for hospitalization'
“Lower respiratory tract infection is a leading cause for hospitalization of infants and young children and accounts for 250,000 hospitalizations a year in the United States alone,” Tobias Allander of the Karolinska Institute in Stockholm and colleagues wrote in their report.
“The most important viral agent in this group of patients is respiratory syncytial virus (RSV). Other important agents are influenza viruses, parainfluenza viruses, adenoviruses, rhinoviruses, coronaviruses, and human metapneumovirus.”
But the causes of between 12 percent and 39 percent of these serious infections are never identified, the researchers said.
In a second study, Janice Louie of the California Department of Health Services, Lawrence Drew of the University of California, San Francisco and colleagues checked patients reporting to the hospital with flulike illness including “unspecified upper respiratory infection,” acute bronchitis, sinus infections and pneumonia.
They could only identify a virus in 103, or 39 percent, of the patients. These included influenza A or B in 54 patients, picornavirus in 28, RSV in 12, human metapneumovirus in four and human coronavirus OC43 in two patients.
