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Long before the 2024 discovery of HPAI H5 avian influenza circulating or spilling over in livestock (see here, here, here, and here) we were watching the evolution and spread of novel coronaviruses in camels, cattle, and pigs.
Coronaviruses are divided into 4 distinct genera; Alphacoronaviruses, Betacoronaviruses, Gammacoronaviruses, and Deltacoronaviruses - and while both birds and mammals are susceptible to coronavirus infection - they each (at least, for the most part) stay in their own lane.
Birds are primarily infected by gammacoronaviruses, such as infectious bronchitis virus (AIBV) and occasionally by deltacoronaviruses, while mammals are primarily affected by alphacoronaviruses and betacoronaviruses.
But there are crossovers.
The announcement, in August of 2013, linking the recently emerged MERS-CoV virus to dromedary camels, was initially greeted by months of denial in Saudi Arabia, but over time the evidence became undeniable (see EID Journal: MERS Coronavirus In A Saudi Dromedary Herd).
In 2014's SECD: Another Emerging Coronavirus Threat we looked at growing concerns that some North American porcine-adapted coronaviruses might have zoonotic potential, given the similar physiology between our two species.
In the summer of 2017 a paper (see EID Journal: A New Bat-HKU2–like Coronavirus in Swine, China, 2017) described a new HKU2-like coronavirus in Chinese pigs showing symptoms of PED (Porcine Epidemic Diarrhea), which they tentatively named porcine enteric alphacoronavirus (PEAV).
As pigs are physiologically fairly close to humans (if that bothers you, think how the pig feels), we watch porcine adapted viruses with particular interest.
In a follow up in 2020, in PNAS: Swine Coronavirus Replicates In Human Cells, we saw additional evidence to suggest that swine coronaviruses might have the `right stuff' to spill over into humans. Researchers demonstrated that the new HKU2-like virus in the 2017 study above (redubbed Swine acute diarrhea syndrome coronavirus (SADS-CoV)) virus replicated efficiently in a variety of human cells, making it potentially a zoonotic threat.
Since then we've see increased warnings on the potential for these novel coronaviruses to spillover into humans (see 2023's J. Med. Virology: Potential Cross-Species Transmission Risks of Emerging Swine Enteric Coronavirus to Human Beings).
And just 2 months ago, in Viruses: Novel Rodent Coronavirus-like Virus Detected Among Beef Cattle with Respiratory Disease in Mexico, we looked at a report on an alphacoronavirus that closely resembles a rodent-coronavirus isolated in China in 2021 (see AFD blog).
There are other reports, including a PLoS Pathogens report last March on the Discovery of a novel Betacoronavirus 1, cpCoV, in goats in China (also cited below), which they described as being closely related to the HKU23- and HKU23-associated coronaviruses.
All of which brings us to a letter, published this week in the Journal of Infection, from Chinese researchers warning on the risks of livestock-borne coronaviruses.
Since its a letter, not a study, I'll just provide the link and highlights. Follow the link to read it in its entirety. I'll have a postscript after the break.
Kaili Qi1 ∙ Jie Chen1 ∙ Xing Ma1 ∙ … ∙ Jin Tian ∙ Ningning Wang ∙ Houqi Jiao … Show more
Highlights
• Emphasizes the threat of livestock coronaviruses to public health.
• The emergence of novel coronaviruses cpCoV in ruminant livestock.
•The neglect of pathogen control and monitoring in global ruminant farming.
• The importance of monitoring ruminant livestock to prevent global zoonotic spillover.
While there is a lot to unpack here, the gist is pretty simple; while scores of new coronaviruses have been discovered over the past 20 years - many with zoonotic potential - our surveillance of ruminant livestock for emerging viruses around the world remains very limited.
After citing many examples, the authors state:
This study highlights the importance of identifying coronavirus diversity and inter-species transmission in ruminants worldwide, broadens our understanding of the ecology of coronaviruses, and aids in the prevention of animal-to-human transmission and outbreaks.
Sadly, most nations continue to follow a `Don't test, don't tell' strategy. What they don't detect, they don't have to deal with.
Until it's too late.
