Influenza was once connected to birds but now that might not be the case. A new study proves that the origins of influenza are connected to the wrong animal after the study found that horses carried influenza before birds. Michael Worobey, a professor at the University of Arizona and an evolutionary biologist examined over 80,000 sequences of genes from influenza illness that were excluded from humans, pigs, horses, birds and bats. He then mapped them according to the evolutionary relationships of viruses and distinct host species.
The map confirmed that birds did carry the virus in 1918 but that horses carried the virus since the 1870s. Worobey comments on his study by saying that the methods that people used for years, which are necessary for finding the origins of gene sequencing and the timing for those events are all flawed. His study also found that a global sweep occurred that destroyed six of the eight influenza genes. These genes are categorized as internal genes, which are responsible for coding proteins. There is evidence that points to horses being the origin of the flu. An equine horse epidemic in 1872 that began near Toronto took the lives of horses all across North America.
An illness similar to influenza was impacting chickens, geese, turkey and ducks around the time the horse epidemic occurred. Worobey says that there is proof that flu that impacted both birds and horses in 1872 were linked. He continues by saying that the evidence is supported by his study and historical evidence corresponds with his theory. This theory, however, is not concrete since it is not scientifically proven that chickens got the flu from horses. It is thought that chickens might have caught it from staying in barns with sick horses or horses could have gotten it from living with sick chickens.
Aside from explaining that the origins of influenza is connected to the wrong animal, his study also reveals the true location of the 1918 flu. The 1918 flu was known as the Spanish flu after the fact that since Spain served as a non-combatant in World War I, most reports of the outbreak came from Spain. However, the first cases of the influenza infection came from people recruiting for the army in Kansas. Worobey explains that his study showed that most of the genes for the 1918 virus came from the line of bird flu that occurred in the Western Hemisphere after the horse flu began in 1872. He also says that people can see that the virus was in the Western Hemisphere a few years before 1918. This is not the first time people stated that birds started influenza. The genetic analysis of tissue from a victim of the 1918 pandemic flu that was pulled from the victim’s body was run in 2005 showed that the virus closely matched the viruses from birds. However, a study in 2009 explained that the genes of the influenza illness was in pigs and humans for two to 15 years before the pandemic occurred and that those viruses combined to form the lethal strain seen today.
Michael Worobey ran a study that examined over 80,000 sequences of genes that were excluded from humans, pigs, bats, horses and birds. He mapped these sequences according to the evolutionary relationships of viruses and the host species. His map showed that birds were the carriers of the 1918 flu epidemic but also that the origins of influenza were connected to the wrong animal. He found that horses were infected with influenza before birds. Oliver Pybus, biologist who studies evolution for the University of Oxford in the United Kingdom, said that the study is a surprise and very fascinating. Pybus also said that people now have the idea that the origin for many of the influenza infection happening now is possibly equine after the view for such a long time was that the source was birds. Gavin Smith, a biologist who studies evolution at Duke-NUS Graduate Medical School at the National University of Singapore, said the study is an essential gift to the way people analyze data.
By Jordan Bonte