Preventing human failings in COVID and African swine fever

Viruses have different superpowers they use to spread among animals and people

With the spread of both COVID-19 and African swine fever (ASF), humans can be their own worst enemies.

That message was delivered by South West Ontario Veterinary Services practitioner Dr. George Charbonneau during the recent virtual edition of the 2021 London Farm Show.

Why it matters: The North American swine sector is on high alert for the arrival of ASF, which has caused major outbreaks and widespread barn depopulation in China and other parts of Asia and Europe.

Charbonneau outlined what he referred to as the “superpowers” of the two high-profile viruses and offered his take on where humans have been successful and not-so-successful in preventing their spread.

Charbonneau noted that although ASF has a high mortality rate — with some outbreaks killing up to 100 per cent of infected pigs — it doesn’t necessarily spread quickly. In some cases, it appears only 30 per cent of those exposed contracted the virus. This is different from something like Porcine Reproductive and Respiratory Syndrome (PRRS), he said, which has a close to 100 per cent infection rate.

This, though, is actually a “superpower” for ASF against efforts to control it; if a producer gets it in their barn, it could take up to three weeks before they know it’s there.

The most significant ASF superpower is survivability. It can persist on cured pork bellies for 60 days, and on cured loins for 83 days.

“So someone brings home a snack of Uncle Ernie’s kielbasa and everybody has to have a taste,” Charbonneau said. Those people get fragments on their clothes and go to the barn, or discard the leftovers somewhere with access to the hogs.

“These pork products from other regions are extremely dangerous.”

ASF also persists on the dead pig’s carcass, surviving in the bones for up to three months at 20C, and in the skin for up to six months at 4C. If an unsuspecting farmer buries a dead pig before realizing it died of ASF, things can get complicated.

“One of the lessons learned is that you can remove the carcass but you really have to sanitize the soil,” the Stratford-based swine veterinarian said.

Most recently, research has proved ASF can survive for weeks in a wide range of feed products.

Controlling COVID

COVID-19, meanwhile, is in the middle of the pack for infection rate, falling below measles and chickenpox on the list. And if humans manage infection control well, Charbonneau stressed, that rate can be decreased to very low.

When it comes to “tenacity… this organism is a bit of a slouch compared to ASF.”

If conditions are really good, it can survive up to 28 days on some surfaces. But it will very likely perish within a few hours on many surfaces or within two to three days on most others.

COVID-19’s main superpower, he offered, is “stealth.” If someone gets a high dose of exposure, it doesn’t typically take too long for it to incubate and for symptoms to show up in humans. But if it’s a low dose of exposure, or especially if the person exposed is asymptomatic, which happens frequently, then the incubation and development of symptoms take place without being noticed and suddenly there’s a significant outbreak.

The problem with humans and viruses

Humans have shown themselves to be their worst enemies, says Charbonneau.

A German veterinarian, having tracked ASF from its introduction into Georgia and subsequent transmission into Europe, commented that the virus “spreads about as quickly as you can drive a truck down the road” — namely, a transporter or unwitting consumer delivering infected pigs or pork products into an unaffected region.

In some countries, the outbreak led to a decrease in prices for pork products in affected regions, Charbonneau said. People would go to those regions because word got out about the low prices. And they would import the infected pork products into the unaffected regions.

“It’s peoples’ stupidity spreading the virus rather than a bunch of wild pigs running around the countryside.”

With COVID, meanwhile, there have been well-documented refusals by segments of the human population to heed the advice of public health specialists for preventing the virus’s spread.

In general, though, there have certainly been similarities between the scientifically backed prevention measures for ASF and for COVID.

In Europe, there has been good use of Controlled Access Zones on ASF-affected swine production facilities — a measure that producers and animal health officials are prepared to also implement in Canada if the virus is detected here.

This includes double-walled perimeter barriers designed to keep infected pigs away from the wild population, and away from human visitors who aren’t designated to enter.

This strength of barrier, and access protocol, is already in place for COVID-19.

“Anybody who visits somebody at a long-term care home knows we’re doing the same thing.” Charbonneau’s mom is currently residing in a long-term care facility.

Incoming and outgoing supplies and equipment must also be disinfected to a similar degree under both the ASF and COVID protocols. And quarantine regimes are essentially the same for COVID as they would be for ASF, if it is detected here.

One difference, Charbonneau noted, is the absence of the requirements for showering before entering a COVID-affected facility, as opposed to what would happen with ASF.

Charbonneau is not aware of any vaccine being developed for ASF. He stressed, though, that it’s unlikely there would be a call in North America for vaccination of the swine herd against the virus. That’s because any vaccination would throw complications into the Canadian and American industries’ efforts to enact strict testing protocols as a means of proving to pork-buying markets that their supplies are ASF free.

About the author

Contributor

Stew Slater

Stew Slater operates a small dairy farm on 150 acres near St. Marys, Ont., and has been writing about rural and agricultural issues since 1999.

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