A new strain of the swine flu virus, identified in pigs in China, could spread to humans and cause a new pandemic such as COVID-19, researchers say.
Experts from the Chinese Academy of Sciences say pigs are an “important intermediate host” or “mixing vessel” for viruses that spread from wild animals to humans.
The Chinese research team has been studying outbreaks of swine flu outbreaks in pig farms across the country since 2011, saying the latest species can be transmitted to humans.
Only two people have confirmed they have contracted the virus, called G4 EA H1N1, since the first outbreak in 2016, but researchers say it is “ highly adapted ” to infect people.
Researchers called for monitoring of farms and people working on or near them, as further transmission could cause the virus to “adapt and become a pandemic.”
The news comes when the world is in the throes of a coronavirus pandemic that started in China and is believed to have passed from bats to humans through an intermediate animal.
The worldwide death toll from Covid-19, the disease caused by this strain of the coronavirus, has now exceeded half a million people.
A strain of the swine flu virus is common in pigs in China and can spread to humans and become a new pandemic, researchers claim. Stock Image
Experts from the Chinese Academy of Sciences say pigs are an “important intermediate host” or “mixing vessel” for viruses that spread from wild animals to humans. Stock Image
The two confirmed cases of the G4 EA H1N1 virus in humans are a 46-year-old diagnosed in 2016 and a 9-year-old diagnosed in 2019.
“Epidemiological studies showed that the two patients had neighbors who kept pigs, suggesting that the G4 EA virus can spread from pigs to humans and lead to serious infection and even death,” the authors say.
Researchers did not address the symptoms, because the virus has not spread widely in humans, but when testing the virus in ferrets they found symptoms such as fever, sneezing, wheezing and coughing were all common.
George Gao, Jinhua Liu and colleagues isolated 179 pig viruses in 10 provinces in China from 2011 to 2018 to study the risks to humans.
They discovered that the G4 strain of H1N1 has ‘all the essential characteristics of a candidate pandemic virus’, and contains elements of the virus that were responsible for the 2009 swine flu pandemic.
They also tested the blood of about 300 pig farmers on 15 different pig farms and found that 10.4 percent had antibodies against G4 EA H1N1, suggesting they had contracted and recovered the virus earlier.
This means that the virus can spread pandemic to people – although they did not say whether it would be as serious as COVID-19 or worse.
They say that measures to control this virus in pigs and to monitor work populations should be implemented quickly to avoid spreading in the future.
“All of this evidence indicates that the G4 EA H1N1 virus is a growing problem on pig farms, and that the widespread circulation of G4 viruses in pigs inevitably increases their exposure to humans,” the study authors wrote in their paper.
Professor James Wood, head of the Department of Veterinary Medicine, University of Cambridge, said pig farming is a huge industry in China.
“The authors conducted a thorough investigation into the risks of newly emerging swine flu viruses in China and show that there is evidence that they may pose a risk to human health,” he said.
He said it was particularly noteworthy that they discovered that the virus can multiply in human cells and may already be infecting some pig farmers.
Another frightening aspect of the discovery, according to Professor Wood, is that “current vaccines may not adequately protect against them.”
“The work reminds us that we are constantly at risk of new emergence of zoonotic agents and of farm animals,” he said.
Wood added that the more we come into contact with wildlife, the more likely these farm animals are “the source of important pandemic viruses.”
Only two people have confirmed they have contracted the virus, called G4 EA H1N1, since the first outbreak in 2016, but researchers say it is “ highly adapted ” to infect people. Stock Image
Dr Alice Hughes, associate professor, Center for Integrative Conservation, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, said viruses like this – swine and bird flu – are not uncommon in China.
She said there have been periodic reports of the outbreak of these viruses, but it is largely limited to livestock – which is why it is screened regularly.
“Hygiene standards and foods, including hormones and steroids in Asia, are likely to contribute to the compromised immune system and the potential for viruses to spread,” Hughes said.
“Pork and poultry are also very popular in Asia, so there are huge numbers of animals in the region – according to current statistics, more than half of the world’s pigs are in China.”
“In summary, G4 EA H1N1 viruses have all the essential features of a high degree of adaptation to humans,” the authors wrote.
“The control of the prevalent G4 EA H1N1 viruses in pigs and careful monitoring of the pig populations must be implemented immediately.”
The findings were published in the journal Proceedings of the National Academy of Sciences.
ZOONOTIC DISEASES: THESE ARE VIRUSES WHICH ARE USUALLY BEGINED IN WILD ANIMALS THAT MAY TRANSFER TO OTHER SPECIES AND SURVIVE
Zoonoses can pass from one species to another.
The infecting agent – called a pathogen – can cross the species boundary in these diseases and still survive.
They vary in potency and are often less dangerous in one species than in another.
To be successful, they rely on long and direct contact with different animals.
Well-known examples are the flu strains that have adapted to survive in humans of different host animals.
H5N1, H7N9 and H5N6 are all strains of avian influenza that come from birds and infected humans.
These cases are rare, but outbreaks occur when a person has long-term, direct exposure to infected animals.
The flu strain is also unable to pass from person to person once a person is infected.
A swine flu outbreak in 2009 – H1N1 – was considered a pandemic and governments spent millions developing ‘tamiflu’ to stop the spread of the disease.
Influenza is zoonotic because as a virus it can evolve rapidly and change its shape and structure.
There are examples of other zoonotic diseases, such as chlamydia.
Chlamydia is a bacterium with many different strains in the general family.
This is known with some specific strains, for example Chlamydia abortion.
This particular bacterium can cause abortion in small ruminants, and when transferred to humans can lead to abortions, premature birth and life-threatening diseases in pregnant women.