H1N1 flu virus shown to be different from seasonal influenza

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By The Staff

WASHINGTON (Reuters) - Autopsies on people who have died from the new pandemic H1N1 flu show this virus is different from seasonal influenza, even if it has not yet caused more deaths, experts told a meeting on Tuesday.

Americans who died from swine flu had infections deep in their lungs, Dr. Sherif Zaki of the U.S. Centers for Disease Control and Prevention told a meeting of flu experts, including damage to the alveoli – the structures in the lung that deliver oxygen to the blood.

This in turn caused what is known as acute respiratory distress syndrome – an often fatal development that leaves patients gasping for breath.

The World Health Organization has confirmed 3,205 deaths globally from swine flu but experts agree all estimates of the extent of the pandemic are grossly understated because so few patients are ever actually tested.

Seasonal flu kills, too – about 250,000 to 500,000 cases a year globally, according to the WHO. But not in the same way as swine flu, which unlike seasonal flu frequently causes severe disease in young adults and children.

“It is very rarely you see what we call diffuse alveolar damage in fatal seasonal influenza,” Zaki told a meeting sponsored by the U.S. Institute of Medicine, which advises government on health matters.

Seasonal flu causes bronchitis and other upper respiratory disease. But Zaki, the chief infectious disease pathologist at CDC, said the new virus had burrowed into the lungs of the 90 or so people he examined after they died, and they had huge amounts of the virus in their blood.

“This is almost exactly what we see with avian flu,” Zaki said. “This looks like avian flu on steroids.”

Read more about the flu in Wednesday's Los Alamos Monitor.