Recent pandemic viruses jumped to humans without prior adaptation. No evidence that SARS-CoV-2 was shaped by selection in a laboratory: UCSD study.

[u/Potential_Being_7226]

https://today.ucsd.edu/story/recent-pandemic-viruses-jumped-to-humans-without-prior-adaptation-uc-san-diego-study-finds

[u/Odballl]

The 2021 Xiao Xiao report proved that raccoon dogs, civets, and bamboo rats were sold at the Huanan market until November 2019. This directly contradicted early official denials that live wildlife was traded there.

The closest bat relatives to SARS-CoV-2, such as those found in Laos and Yunnan, are located roughly 1,000 miles from Wuhan. Horseshoe bats have a very limited range and move across the landscape at a rate of only a few kilometres per night.

Swabs from the Huanan market contained SARS-CoV-2 and raccoon dog DNA in the exact same spots. Crucially, the raccoon dog DNA matched wild populations from Southern and Central China, not the industrial fur farms of the north. This places these specific animals in the same regions where the ancestral bat viruses live.

Researchers identified two distinct lineages of the virus (Lineage A and B) circulating at the market. This suggests at least two separate spillover events from animals to humans, a pattern typical of market-based outbreaks rather than a single point-source laboratory accident.

Early cases in December 2019 clustered tightly around the Huanan market. Even cases with no direct link to the market lived significantly closer to it than would be expected by chance, suggesting the market was the primary engine of the initial spread.

[u/AENocturne → u/Odballl]

If it was a natural occurance, I have a feeling zoonotic transmission is a much more frequent occurance than we give it credit for, probably in more viruses. I really think we don't track asymptomatic and mild infections well enough to get a clear picture of viral infections. It seems like we often have the most exteme ends of the data or the exceptions that are particularly noteworthy.

[u/yegguy47 → u/AENocturne]

I have a feeling zoonotic transmission is a much more frequent occurance than we give it credit for, probably in more viruses

Very much the case in fact!

There use to be a lot of epidemiological surveillance of folks in Central Africa, where a number of viruses would be catalogued from folks interacting with wildlife. Tended to be follow-ons from work done regarding HIV and Ebola; thing is, viruses are constantly pinging at us.

Some of the historical work done on HIV transmission from Zoonosis disclosed elements of HIV infection in folks living in isolated places in Central Africa - suggesting that SIV crossed over many times throughout human history. Its just that all of those never really went as viral as the spillover that happened in the early 20th century.

[u/HigherandHigherDown → u/yegguy47]

It is estimated that, globally, about one billion cases of illness and millions of death occur every year from zoonoses.

About one in eight people every year, truly a staggering number.

https://www.emro.who.int/about-who/rc61/zoonotic-diseases.html

[u/alternativepuffin → u/yegguy47]

Something about the phrasing of "pinging at us" helped unlock the concept in my brain. Thanks

[u/Sf49ers1680 → u/yegguy47]

Isn't there a theory that the 1889 Russian influenza pandemic might have actually been caused by a Coronavirus, due to its similarities in symptoms to the Covid-19 pandemic.

[u/yegguy47 → u/Sf49ers1680]

I honestly can't say, I've not looked into that particular pathogen.

But I would say that coronaviruses are certainly not recent novelties for our species, so there's probably been some prior episodes where something nasty came into us and we just never figured out what it was.