Swine flu damage reaches deep into lungs: Study

Swine flu damages the entire airway, from the trachea to deep in the lungs, just as the

viruses that caused the deadly 1918 and 1957 influenza pandemics did, but unlike seasonal

flu, a report has said.

Scientists from the National Institutes of Health (NIH) and New York City's chief medical

examiner's office examined microscope slides of tissue from 34 people who died of pandemic

swine flu earlier this year.

They found "a spectrum of damage in both the upper and lower respiratory tracts," Jeffery

Taubenberger, one of the researchers on the study, said yesterday.

In all cases, the upper respiratory tract -- the trachea and bronchial tubes -- were

inflamed and sometimes severely damaged.

In 18 cases, or more than half, damage was seen lower down, in the finer branches of the

bronchial tubes, and in 25 cases, or nearly three-quarters of the study sample, the

researchers found damage to the small globular air sacs, or alveoli, of the lungs.

"This pattern of pathology in the airway tissues is similar to that reported in victims of

both the 1918 and 1957 influenza pandemics," said Taubenberger, a virus specialist at the

National Institutes of Allergy and Infectious Diseases (NIAID).

But it differed from seasonal flu, which "causes most damage in the trachea and the

bronchial tree, not deep in the lungs," Taubenberger said.