14 DAY TRIAL // Nearly 100 years ago, the world was decimated by the 1918 Spanish influenza outbreak. Between 3 and 5 percent of the world's population died following infection, but researchers were until now unable to figure out how it all started. A new study finally proves that the virus originated in domestic and wild birds living in North America.
The outbreak was termed the Spanish flu on account of the fact that the media only reported the true extent of the virus' reach for countries that were not a part of the war effort. Many outlets censored the amount of data they provided on the flu epidemic, thus creating the false impression that Spain was hit hardest. In fact, this was the first global outbreak in human history.
The Spanish flu affected people at both poles, and on remote and isolated Pacific Islands, the first time that a disease is not contained in a single country or continent. This epidemic was also the first to highlight the dangers of a tightly-interconnected world, Nature News reports.
The new investigation was carried out by researchers at the University of Arizona in Tucson, who were led by ecologist and evolutionary biologist Michael Worobey. He was also the lead author of a paper detailing the findings, which appeared in last week's issue of the top scientific journal Nature.
Researchers were able to track the genetic traces the virus left behind in various animal species over the past 200 years. The work proved that the 1918 avian flu strain did not originate in the mixing of human and swine flu viruses, as some investigators had proposed.
“Worobey's study is highly persuasive. It shows the evidence for a pig origin is a lot weaker, but it’s almost impossible to completely shut the door on that,” comments University of Oxford evolutionary biologist Oliver Pybus, who was not a part of the research team.
“The methods we’ve been using for years and years, and which are crucial to figuring out the origins of gene sequences and the timing of those events, are all flawed,” Worobey says. The researcher analyzed more than 80,000 gene sequences collected from bodies frozen during the epidemic for this study.
Another important discovery is that all avian flu strains in the world today share genetic similarities to a flu strain called H7N7, which attacked horses and mules throughout North America during an epidemic in 1872.
“We now have this idea that the source for a lot of influenza virus we see now worldwide is potentially equine, whereas the dogma has been for so long that its avian. It’s a fascinating study, and quite a surprise,” Pybus comments.