I’ve been slow posting in the past few days, so here are a few quick recaps from the animal/COVID-19 world.
Back in April, a paper (Xia 2020) was released that suggested dogs could be the source of SARS-CoV-2. Most of us considered it crap at the time (read more about it in our previous post), and most people moved on pretty quickly, but it still left some fear and poor messaging in its wake. Now, a proper dismissal of this paper (in the same journal) has been published. I won’t get into the details, but it basically says “Everything that was written in that paper… yeah, not so much.”
More formally, here’s what they concluded: “In summary, the proposition of Xia (2020) that dogs are a likely pre-human host for SARS-CoV-2 is not justified by available evidence. Xia (2020) did not demonstrate that the low CpG frequency in the SARS- CoV-2 genome was driven by a unique selective environment in dog digestive tracts. The SARS-CoV-2 is also less virulent than other human betacoronaviruses (SARS-CoV-1 and MERS-CoV), contradicting his assertion that CpG-deficient viruses are more virulent. Furthermore, closely related betacoronaviruses from bats and pangolins have CpG-deficiencies similar to SARS-CoV-2. Dogs are not more plausible than most other potential host species, and based on current data, far less plausible than bats or pangolins. Still, we are missing ~20-70 years of the recent evolutionary history of the lineage leading to SARS-CoV-2, and we must broadly survey a wide range of wild and domestic species to uncover the origin of SARS-like coronaviruses.”
More SARS-CoV-2 in mink
Mink are really susceptible to this virus, and human-to-mink transmission seems to occur quite easy. In the Netherlands, SARS-CoV-2 has infected mink on at least 24 farms, with widespread disease in mink and even some plausible mink-to-human transmission. There was a plan to end the mink industry in the Netherlands by 2024, and this crisis appears to be speeding things up as mink on affected farms are culled.
In Denmark, multiple farms have also been affected. They’re taking a different approach there, now choosing not to cull affected mink farms, but putting strict measures in place to control any outbreaks and monitoring closely for more.
In Canada, so far, so good. Since infection with SARS-CoV-2 in mink was first reported, there’s been an emphasis on biosecurity measures to avoid infecting mink, and relatively low disease rates in people in Canada (at the moment) mean the risk is currently fairly low. However, it’s still a concern. An additional worry is mink farms becoming a source the virus that could spread to wildlife. Feral cats have been infected on at least one affected mink farm in the Netherlands. Spread to wild mink (which are present throughout Canada and the US) is an even bigger concern given how susceptible this species is. We don’t want to create a wildlife reservoir of SARS-CoV-2, either through spread from farms to wild animals or from escape of farmed mink.
Human-to-pets transmission is still a thing
Reports of cases of human-to-pet transmission of SARS-CoV-2 continue to trickle in, and probably represent a small fraction of cases that actually occur. I’m sticking to my promise not to report each new case if there’s not really anything new about it. Infections in pets are still uncommonly reported, but a lot of cases are likely not detected because there’s limited testing. The animal and public health risks of these cases are probably very limited regardless, especially in places where there’s rampant human-to-human transmission. But, we’d still like to contain exposed animals to prevent them from playing any relevant role.
Still no signs of infection in livestock
So far, so good on the livestock front. Fortunately, major livestock species do not seem to be overly (or at all) susceptible to SARS-CoV-2. We still need to pay attention to this though, and I think the message “If you might be infected, stay away from animals” remains important, regardless of the species. However, the risk of significant issues from livestock seems pretty limited right now.
Still looking for the animal origin of SARS-CoV-2
This is still a huge question. It seems a little late, but the World Health Organization has sent a team to China to further investigate the animal origin of the virus. Kind of. They’ve sent two people there to discuss a larger investigation. It might be a challenge to find the animal source but we still have to try. We need to know if this virus is still lurking somewhere in the wild, and where. We also need to understand how and why this outbreak happened, to help prevent it from happening again (with this virus or one of many other potentially nasty bugs that are no doubt also lurking in the wild).