Researchers Unlock Secrets of 1918 Flu Pandemic
Posted on December 29, 2008
What a year this has been. A stock market crash, housing crash, recession and rising unemployment. Now just to end out the year, the Middle East is erupting yet again. But wait, there's more! As flu season approaches, researchers have discovered why the 1918 flu pandemic (which killed more people than all the wars in modern history combined) was so deadly. The virus contains three genes which together allow the the virus to invade the lungs and cause pneumonia.
The discovery, published in Tuesday's issue of the Proceedings of the National Academy of Sciences, could also point to mutations that might turn ordinary flu into a dangerous pandemic strain. Yoshihiro Kawaoka of the University of Wisconsin and colleagues at the Universities of Kobe and Tokyo in Japan used ferrets, which develop flu in ways very similar to humans. Usually flu causes an upper respiratory infection affecting the nose and throat, as well as so-called systemic illness causing fever, muscle aches and weakness. But some people become seriously ill and develop pneumonia. Sometimes bacteria cause the pneumonia and sometimes flu does it directly.So when you need a break from thinking about your 401k, you can always ponder the coming flu pandemic that could kill upwards of 50 million people.During pandemics, such as in 1918, a new and more dangerous flu strain emerges. "The 1918 influenza pandemic was the most devastating outbreak of infectious disease in human history, accounting for about 50 million deaths worldwide," Kawaoka's team wrote. It killed 2.5 percent of victims, compared to fewer than 1 percent during most annual flu epidemics. Autopsies showed many of the victims, often otherwise healthy young adults, died of severe pneumonia. "We wanted to know why the 1918 flu caused severe pneumonia," Kawaoka said in a statement.
They painstakingly substituted single genes from the 1918 virus into modern flu viruses and, one after another, they acted like garden-variety flu, infecting only the upper respiratory tract. But a complex of three genes helped to make the virus live and reproduce deep in the lungs. The three genes -- called PA, PB1, and PB2 -- along with a 1918 version of the nucleoprotein or NP gene, made modern seasonal flu kill ferrets in much the same way as the original 1918 flu, Kawaoka's team found.
Most flu experts agree that a pandemic of influenza will almost certainly strike again. No one knows when or what strain it will be but one big suspect now is the H5N1 avian influenza virus. H5N1 is circulating among poultry in Asia, Europe and parts of Africa. It rarely affects humans but has killed 247 of the 391 people infected since 2003. A few mutations would make it into a pandemic strain that could kill millions globally within a few months.