Researchers discovered the 1918 flu pandemic so deadly a group of 3 genes that lets the virus invade the lungs & cause pneumonia. The researcher actually mixed the samples of 1918 influenza strain with modern seasonal flu viruses to find the 3 genes that might help in the development of new flu drugs. The discovery could also point to mutations that might turn ordinary flu into a dangerous pandemic strain.
Usually flu causes an upper respiratory infection affecting the nose and throat, and so called systemic illness causing fever, muscle aches & weakness. But some people become seriously ill and develop pneumonia. Sometimes bacteria cause the pneumonia and sometimes flu does it directly. 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 but It killed 2.5% of victims, compared to fewer than 1% during most annual flu epidemics. Autopsies showed many of the victims, often otherwise healthy young adults, died of severe pneumonia. 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 3 genes helped to make the virus live and reproduce deep in the lungs. The 3 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. 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. Four licensed drugs can fight flu but the viruses regularly mutate into resistant forms just as bacteria evolve into forms that evade antibiotics.
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