Swine Flu More Dangerous Than Suspected

ScienceDaily (July 14, 2009) — A new, highly detailed study of the H1N1 flu virus shows that the pathogen is more virulent than previously thought.

Writing in a fast-tracked report published July 13, 2009 in the journal Nature, an international team of researchers led by UW-Madison virologist Yoshihiro Kawaoka provides a detailed portrait of the pandemic virus and its pathogenic qualities.

In contrast with run-of-the-mill seasonal flu viruses, the H1N1virus exhibits an ability to infect cells deep in the lungs, where it can cause pneumonia and, in severe cases, death. Seasonal viruses typically infect only cells in the upper respiratory system.

"There is a misunderstanding about this virus," says Kawaoka, a professor of pathobiological sciences at the UW-Madison School of Veterinary Medicine and a leading authority on influenza. "People think this pathogen may be similar to seasonal influenza. This study shows that is not the case. There is clear evidence the virus is different than seasonal influenza."

The ability to infect the lungs, notes Kawaoka, is a quality frighteningly similar to those of other pandemic viruses, notably the 1918 virus, which killed tens of millions of people at the tail end of World War I. There are likely other similarities to the 1918 virus, says Kawaoka, as the study also showed that people born before 1918 harbor antibodies that protect against the new H1N1 virus.

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90-year Evolution Of Swine Flu

ScienceDaily (July 5, 2009) — The current H1N1 swine flu strain has genetic roots in an illness that sickened pigs at the 1918 Cedar Rapids Swine Show in Iowa, report infectious disease experts at the University of Pittsburgh Graduate School of Public Health in the New England Journal of Medicine. Their paper, published online June 29 and slated for the July 16 print issue, describes H1N1's nearly century-long and often convoluted journey, which may include the accidental resurrection of an extinct strain.

"At the same time the 1918 flu pandemic was rapidly spreading among humans, pigs were hit with a respiratory illness that closely resembled symptoms seen in people," said senior author Donald S. Burke, M.D., dean, University of Pittsburgh Graduate School of Public Health. "Early experiments confirmed that this 1918 swine virus and a human strain emerged about the same time. Since then, this ancestor virus has re-assorted genetically with other influenza strains at least four times, leading to the emergence of the new 2009 strain, which has retained some similarities to the original virus."

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