Chinese scientists have found a new swine flu strain in pigs in Chinese slaughterhouses and veterinary hospitals which has the potential to become the next pandemic if it transmits among humans. The researchers found that 10% of the swine workers contracted the new virus but there has been no evidence to show that these workers further transmitted the virus to other humans.
The scientists have named this virus G4 EA H1N1 as it is genetically similar to the H1N1 virus that caused the 2009 pandemic. The study published on June 29 in American journal PNAS finds that this new virus strain is a combination of three earlier strains- one strain from European and Asian birds (EA), the H1N1 flu strain, and a North American flu that carries genes from birds, pigs, and humans.
The scientists further highlighted that this virus possesses "all the essential hallmarks of highly affecting humans". These findings emerge from a decade long influenza surveillance carried out by these scientists.
The researchers took 30,000 nasal swabs from slaughterhouses in 10 Chinese provinces and found 179 different virus strains between 2011 and 2018. This particular strain was seen to be predominant among pigs since 2016. According to the scientists, they chose to focus on pigs as they are known to be hosts to several influenza viruses that later emerge as pandemics.
The study is more worrying as the world is still struggling to tackle the current SARS-CoV-2 pandemic which has infected over one crore people and has claimed over five lakh lives. The worst affected countries are USA, Brazil, Russia, and India.
What Did The Study Find?
As this virus is a blend of three various strains, the researchers highlighted that pre-existing immunity to the influenza or swine flu strains will not be effective against this strain. If this strain does transmit among humans, a new vaccine will have to be developed for developing immunity. The researchers have asked for strengthening surveillance in pigs and monitoring workers who work with pigs.
The scientists also chose to study this virus in ferrets as well as human epithelial cells of the lungs. Ferrets were chosen as their respiratory systems are similar to those of humans. The G4 virus strain was found to be more infectious than the other EA H1N1 strains in ferrets. In the human epithelial cells, the virus replicated faster after 36-60 hours of infection.
To understand whether the virus has transmitted to humans, the researchers also collected blood and serum samples from a few workers on swine farms and some from the general population. The scientists found that 10.4% of the swine workers from the 338 samples they had collected had already been infected by the virus. They also found that 4.4% of the general population living around pig farms had also developed antibodies for the virus.
In 2016 and 2019, the scientists found that a 46-year-old and a 9-year-old had been infected by the G4 but they did not further transmit the virus.
The H1N1 Pandemic
This surveillance highlighted that the number of pigs with any kind of viruses increased from 1.4% in 2011 to 8.2% in 2018. This is worrying as the H1N1 pandemic emerged from pigs.
According to the American Centres for Disease Control and Prevention, the 2009 H1N1 pandemic was different as people older than 60 had developed antibodies against the virus while people younger than 60 were more susceptible to the virus.
The CDC estimated that 1,51,700-5,75,400 people worldwide died from (H1N1) virus infection in the first year.
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