The US Department of Agriculture last week reported a deadly case of H7N3 bird flu in a turkey flock in Chesterfield county, South Carolina. The virus killed 1,583 turkeys and the remaining 32,577 birds have since been euthanized. In a statement, USDA said there was no immediate public health concern and that no human cases of the virus had been detected.
The European Union banned all U.S. poultry products last Friday, but it already restricts most imports over using chemicals to sanitize chicken carcasses. China, Canada, Mexico and others have only banned poultry slaughtered and processed in South Carolina or the county where highly pathogenic avian influenza was confirmed in a turkey flock on April 8. Globally, more than +60 cases of highly pathogenic avian influenza (HPAI) have now been confirmed in Hungarian poultry flocks in less than one month. Bulgaria, Taiwan, and Vietnam have also reported new cases.
With the fatal strain of bird flu confirmed here in the U.S., many are now wondering if they need to worry about the pathogen transferring or jumping to other species. Wild waterfowl and swine can harbor strains of the fast-mutating influenza A that are distinct from the strains that cause cases of seasonal flu. When a strain jumps from animals to humans, it can be particularly dangerous. Perhaps the best-known example of this is the 1918 flu pandemic, which killed between 50 and 100 million people around the world.
Chinese authorities fear a new virus outbreak after a three-year-old girl recently contracted the N9N2 strain of avian influenza, as the country emerges from the coronavirus pandemic. The child in Guangdong province had been in contact with domestic poultry before she fell ill, according to the World Health Organization (WHO). Bottom line, tthe recent emergence of the coronavirus behind the COVID-19 pandemic has thrown a spotlight on the risks that animals can nw pose to humans as the source of new viruses.
From research over the past few decades, scientists now understand some of the mechanisms that contribute to virus jumping between species. Influenza virus is a classic example… The virus contains eight genome segments and if two different viruses infect the same cell, segments from both can mix to create a novel virus species. If the proteins on the surface of the new virus have significantly changed from currently circulating influenza virus strains, then no one will have immunity and the new virus can easily spread.
Humans have always come into contact with new viruses as they have explored new areas and spread across the globe. It’s unclear what changed in the recent viruses to allow them ot more easily infect humans. However, given that three major diseases have emerged from the coronavirus family in the last 20 years – SARS, MERS and now COVID-19 – it is likely that this will not be the last time a coronavirus jumps into humans and causes a new disease outbreak. There’s just a lot here we still don’t know and fully understand. It feels like we are just seeing the tip of the iceberg…
