Did SARS-CoV-2 Originate in Animal Markets?
Jason Kindrachuk, PhD, explains the animal reservoir spillover events involved in the emergence of viruses like SARS-CoV-2.
Segment Description: Jason Kindrachuk, PhD, explains the animal reservoir spillover events involved in the emergence of viruses like SARS-CoV-2. Dr. Kindrachuk is a professor of viral pathogenesis at the Medical Microbiology Department of the University of Manitoba.
This is part 3 of a 3-part interview. It can be understood either alone or in context.
Interview Transcript (modified slightly for readability):
Contagion®: The animal markets that the virus has been connected to, they're sort of treated as this cultural long standing institution, but they really only popped up in urban centers a few decades ago, in the context of political and economic changes that were happening in China.
How certain are we about the animal market origin of SARS-CoV-2, and how would that transfer occur? There's sort of this apocryphal tale that goes around of bat guano and a pangolin. But you also have a lot of blood transfer going on in these in these markets,
Kindrachuk: I’ll go back to my experiences with Ebola in West Africa and as a researcher, because we think with very high certainty that Ebola spilled over from bats, and the likelihood is food markets or game markets played a role in transmission.
It’s worldwide. But of course, China is in the spotlight right now.
What we know as far as SARS-CoV-2 is that the initial reports of emergence on New Year's Eve, We looked at this atypical pneumonia cluster that all happened in Wuhan, and had a relationship back to this 1 single animal market.
Well, what we know now is that there were cases that predated that cluster of folks that were at the animal market, and were identified in patients that had no contact with the animal market. That doesn't necessarily take the animal market itself completely out of the equation. What may have happened is there may have been some sort of event where somebody that may have been infected with SARS-CoV-2 may have gone into the market and amplified the transmission amongst people there.
All the sequencing data so far suggests that this wasn't a virus that was continually spilling over from animal species, that the likelihood was that it spilled over in a single event to humans. And then from there transmitted from human to human and was spread widely.
It argues against this idea that that animal market passed it on.
We can take a step back and say, okay, the likelihood is that event at that single animal market is not responsible. It likely was some sort of contact between humans and animals from which to spilled over.
Contagion®: The exotic animal trade exists outside of just these animal markets that they're connected to..
Kindrachuk: 100% right. These viruses also don't require a bat directly to come and bite a human to transfer the virus. It can be just the handling of a bat, whether or not the bat is dead or alive. If somebody has simple things like abrasions on their skin, or has close contact with that animal and any biological fluids spray into their face or enter through a cut, that could be enough.
We do need to figure out, what was the underlying event from which this occurred? And as well, are there other animal intermediate hosts that may be playing a role in this? Was it, rather than a bat directly to human, was it a bat to another animal, and that animal was actually where there was human contact and through biological fluid or just direct handling that virus transmitted?
Contagion®: So, despite the uncertainty about the animal market connection, there have been efforts to curb these, after decades including them still existing between SARS and what’s kind of a SARS-2.
But if you were to outright ban them, there are loopholes already that involve medicine. And if you were to outright ban these markets, the associated animal trade may not go away as much as go into a black market that pushes these markets out to the rural context.
That could make these outbreaks actually harder to control if you have people coming from many different areas rather than concentrated. Does that sound like it could present a problem?
Kindrachuk: Absolutely. We've seen these issues with Central Africa and West Africa, right?
A lot of these game markets have been made illegal. The problem is that we know that those game markets still exist. It's just the authorities don't necessarily know for certain where they are or what is being distributed at those markets.
It’s a bit of a catch 22. You don’t want live animal markets providing the ability for people to be in contact with a lot of exotic animals. We know in terms of animal welfare, there are a litany of questions and ethical questions regarding them, which I unabashedly agree with.
My concern is that we also don't want to drive them underground, so that it becomes much harder to track, because we know that there is a linkage between emerging viruses and markets such as these.
Driving them into the underground will make things a lot harder for us to track from a surveillance standpoint and from a pandemic preparedness standpoint if that was to occur,
Contagion®: If these do end up remaining a perennial issue in some urban centers, in China or elsewhere, not to single them out, what kind of mitigating or regulatory measures could limit the damage at least by making them more hygienic, if you had inspections or something like that?
Kindrachuk: One of the things discussed a lot with colleagues in both West and Central Africa is that we can't go into different regions and say to people, you can't do this anymore. Because we know that from a cultural sensitivity standpoint, we need to be more sensitive. We also know that is going to drive divides between authorities, and regions of the world against one another. From an educational standpoint, it requires us going in and trying to figure out how to essentially mitigate those contacts.
So is it as simple as trying to figure out how people are actually coming in contact with biological fluids, how they're handling the animals? Providing some amount of personal protective equipment for people, that may be able to reduce exposures. Or for people that do have potential exposures, provide them with some sort of network where they can provide information that they were exposed, or there was an exposure event without concerns about repercussions, and also being provided with care and diagnostic measures to see whether or not they have been infected with anything.
I think trying to bring the public back into this is a critical point, we need to build back public trust.
Contagion®: In order to think about these animal markets in a context that's broader than just singling out China or animal markets, are there any other agricultural practices around the world, including in the West that appear to be incubating dangerous pathogens? I mean, I know antibiotic resistance is its own question there as well.
Kindrachuk: This is a point that’s been discussed after the 2014 West African Ebola epidemic, in regards to what are the major factors that are precipitating spillovers?
One of the things that people have been looking at fairly recently is deforestation. Things like clear cutting, in particular within tropical regions where we know it's just a perfect environment for these viruses in terms of hosts and climate, where we are putting humans in closer contact with animals that they would not have come into contact with before and increasing the chances for spill overs.
It’s easy enough to say if we just stop deforestation and clear cutting, that may reduce this. But what we’ve actually found is that there was more of a link to spillover events with smaller pockets of deforestation, as opposed to a larger clear cutting.
There needs to be better planning in primarily low- and middle-income regions which are around the tropics to try and devise a strategy that is going to reduce spillover events, in particular with bat populations and rodent populations.
Contagion®: Let’s hope this is a wakeup call to for global preparedness in terms of surge capacity at hospitals, and in terms of coronaviruses.
Kindrachuk: With coronaviruses, we said after SARS that that they were a potential global pandemic threat. We know WHO a couple years ago had classified them as such. But they're understudied. What we're seeing is what happens when you have that one virus that spills over where you have no preexisting immunity in the population. You have no vaccines, we have no therapeutics,
Contagion®: There are all these comparisons made between COVID and flu, but that's kind of apples and oranges. If the first time we ever experienced influenza was 2020 AD, we would be just as overwhelmed. And that doesn’t have to do with the mortality rate of flu today, with immunity.
Kindrachuk: What a lot of us had been arguing for years is that we have to look at these events as realistic. It's not a matter of if, it's a matter of when.
Hopefully this is a wakeup call. Let's get through the pandemic. But I think afterwards it's going to be a global effort and country by country effort to try and revitalize how we look at pandemic preparedness reflection,
Contagion®: Definitely necessary. Thank you so much for sitting down with me and talking Dr. Kindrachuk.