A new strain of flu virus spreading in Chinese pigs may also infect humans and become another pandemic as human beings have no immunity against it.
According to Chinese researchers, the flu has become more infectious to humans and needs to be watched closely in case it becomes a potential “pandemic virus.”
Experts however said there is no imminent threat to mankind..
A team of Chinese researchers looked at influenza viruses found in pigs from 2011 to 2018 and found a “G4” strain of H1N1 that has “all the essential hallmarks of a candidate pandemic virus.”
The team’s paper was published by the US journal, Proceedings of the National Academy of Sciences (PNAS).
Pig farm workers also showed elevated levels of the virus in their blood, the authors said, adding that “close monitoring in human populations, especially the workers in the swine industry, should be urgently implemented.”
The recently emerged genotype 4 (G4) reassortant Eurasian avian-like (EA) H1N1 virus was found after testing over 30,000 swabs from pigs across 10 provinces including from samples that displayed respiratory symptoms.
The study was conducted over seven years, and discovered virus strains that predominantly were from a variant categorised as G4.
The G4 variant is of concern because its core is an avian influenza virus to which humans have no proven immunity.
This is the reason researchers have called for anticipatory vaccines and preparation against G4 swine flu viruses.
Called G4 EA H1N1, the swine flu strain bears genes similar to those in the virus that caused the 2009 flu pandemic, according to the study.
The study found that 10.4 per cent of swine workers were positive for G4 virus, especially for participants from 18 years to 35 years old, who had 20.5 per cent seropositive rates, indicating that the predominant G4 virus has acquired increased human infectivity.
The human infections indicate that the flu strain “possesses all of the essential hallmarks of a candidate pandemic virus” and that it poses “a serious threat to human health,” the researchers concluded.
Zoonoses, diseases that jump from animals to humans, are one of the most common sources of dangerous new infections.
Ebola, HIV, and the coronavirus itself are all examples of deadly pathogens that originated in animals.
The study highlights the risks of viruses crossing the species barrier into humans, especially in densely populated regions in China, where millions live in close proximity to farms, breeding facilities, slaughterhouses and wet markets.
The coronavirus that caused the worldwide COVID-19 pandemic is believed to have originated in horseshoe bats in southwest China and could have spread to humans via a seafood market in Wuhan, where the virus was first identified.
The PNAS study said pigs are considered important “mixing vessels” for the generation of pandemic influenza viruses and called for “systematic surveillance” of the problem.
China took action against an outbreak of avian H1N1 in 2009, restricting incoming flights from affected countries and putting tens of thousands of people into quarantine.
The new virus identified in the study is a recombination of the 2009 H1N1 variant and a once prevalent strain found in pigs.
But while it is capable of infecting humans, there is no imminent risk of a new pandemic, said Carl Bergstrom, a biologist at the University of Washington.
“There’s no evidence that G4 is circulating in humans, despite five years of extensive exposure,” he said on Twitter after the paper’s publication.
“That’s the context to keep in mind.”