NEW YORK, Oct 19 (Reuters Health) -- Hospitalization rates for US children with bronchiolitis, a lung infection caused by a common virus, rose "substantially" between 1980 and 1996. A new study of national data on this infant disease suggests that hospitalizations for lung disorders caused by the bronchiolitis virus are up to 2 times greater than previously estimated.
Bronchiolitis, a disease in infants, is caused by respiratory syncytial virus (RSV). Almost all children get RSV infections, but their first infection, usually between the ages of 1 and 3 months, is the one most likely to be severe enough to require hospitalization, according to the authors of a report published Wednesday in The Journal of the American Medical Association (JAMA).
The finding that bronchiolitis hospitalizations have increased substantially during the 17 years studied "was not expected," according to Dr. David Shay from the Centers for Disease Control and Prevention in Atlanta, Georgia and his co-authors.
During the 17 years studied, more than 1.6 million children under the age of 5 years were hospitalized for bronchiolitis, the majority of them (57%) under 6 months old, the results indicate.
Between 1980 and 1996, the bronchiolitis hospitalizations increased for children of all age groups, the investigators report. "The most dramatic rise in hospitalizations occurred among children younger than 6 months, for whom bronchiolitis hospitalizations increased by 239% from 1980 to 1996," they write.
Bronchiolitis also accounted for an increasing proportion of all hospitalizations during the period studied. According to the report, the proportion of all hospitalizations for bronchiolitis more than tripled for the under 1 year age group, from 5.4% to 16.4%.
The results indicate that bronchiolitis was more likely to occur during the winter months and that boys were 1.6 times more likely to be hospitalized with bronchiolitis than girls.
The investigators propose several reasons to account for the increasing number of RSV-related bronchiolitis hospitalizations. Greater attendance at child-care centers during the first 2 years of life increases the risk of acquiring a lower respiratory tract infection, they explain. Newer methods of monitoring the blood oxygen levels might also have resulted in more frequent diagnoses of severe lung infection. Improved survival of premature infants might contribute to the rise, the researchers note, though they represent a small minority of cases.
Since most cases of bronchiolitis result from RSV infections, the authors conclude that "a safe and effective RSV vaccine is needed to reduce bronchiolitis hospitalizations." Such vaccines, they note, are currently still in the development stages.
