Three Genes Made 1918 Flu So Deadly
They cause pneumonia by letting virus into lungs
By Matt Cantor,  Newser User
Posted Dec 30, 2008 2:58 PM CST
Masked doctors and nurses treat flu patients lying on cots and in outdoor tents at a hospital camp during the influenza epidemic of 1918.   (Getty Images)
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(Newser) – Researchers have pinpointed the reason the flu pandemic of 1918 was “the most devastating outbreak of infectious disease in human history,” Reuters reports. The key is a combination of three genes that allowed the virus to enter the lungs and cause pneumonia. Typically, the flu affects only the upper respiratory tract. The scientists made their discovery by mixing strains of the 1918 flu with modern ones.

The 1918 flu killed about 50 million people, or 2.5% of victims, compared with less than 1% for most seasonal flu outbreaks; many of those who died showed signs of pneumonia. The scientists, based in Wisconsin and Japan, say their research could help in the development of flu medication and provide insight into how modern flu strains could turn
more threatening.