Preserved tissue taken from 68 soldiers who died from flu in 1918 show the influenza virus did not undergo some strange mutation that made it especially deadly, U.S. researchers reported Monday.
In fact, the very same version of H1N1 flu was circulating for months before it finally sparked a pandemic that swept around the globe during World War I, killing as many as 50 million people, Dr. Jeffery Taubenberger of the National Institute of Allergy and Infectious Diseases and colleagues reported.
“These findings have important implications for understanding the origins and evolution of pandemic influenza viruses,” they wrote in their report, published in the Proceedings of the National Academy of Sciences.
The H1N1 virus that caused the 1918 pandemic is a distant ancestor of the H1N1 swine flu currently circulating, which caused a mild pandemic when it emerged in 2009. Researchers are worried that a new virus could emerge that would cause an even more deadly pandemic and are trying to learn as much as possible to help the world prepare before that happens.
The report has some reassurances. All 68 of the soldiers whose preserved tissue was studied also had infections with bacteria – called bacterial co-infections. In the days before antibiotics these could be highly deadly, but modern antibiotics make it much more unlikely a patient will die. However, many of the victims of the 2009 pandemic, which killed about 12,000 Americans, according to Centers for Disease Control and Prevention estimates, had bacterial co-infections.
Taubenberger’s team studied preserved samples from autopsies of the 68 soldiers. They managed to find pieces of genetic material of flu virus in 37, including four samples taken from the earliest known victims of the 1918 pandemic.
They found the virus was identical to viral samples taken from later in the pandemic. Their findings confirm theories that this particular strain of H1N1 flu virus circulated quietly for months before the pandemic really developed. But they don’t explain why the 1918 pandemic killed so many people – an estimated 3 percent of victims, a very high percentage for influenza.
Vaccines prevent flu very well and antiviral drugs can help patients with severe infections to recover. But scientists fear a completely new flu virus could emerge and spread quickly before a vaccine could be developed. Current processes for making flu vaccines take months. And flu viruses quickly evolve resistance to antiviral drugs, making them less useful.
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