African swine fever keeps pig vet up at night

As a swine veterinarian practising in Manitoba for 18 years, my days are typically spent dealing with health and productivity challenges in hog operations of various shapes and sizes.

One of the things that all of these very different farms have in common is the risk of a foreign animal disease entering Canada and the impact that it would have on their farms.

African swine fever is a hemorrhagic disease of pigs not currently found in North America. Clinical signs of ASF infection include high fevers, pregnancy loss and bloody diarrhea (ASF causes bleeding in many different body organs) with affected pigs developing red-purple ears, bellies and legs.

As the name implies, ASF originated in Africa, where it circulates in wild pigs. The virus does not infect people (only pigs) and has no impact on food safety, but it has some interesting characteristics.

In viral terms, ASF is huge. Its size and strain variation have made effective vaccine development impossible. ASF kills 20 to 100 percent of infected populations and is able to withstand many disinfectants and drying, making it persist in infected tissues for a long time.

Fresh chilled meat and dried cured sausages contaminated with ASF will harbour live virus for weeks and even months. Once frozen, the virus will remain viable indefinitely. This is one tough nut.

One of the only ways to kill the virus is to cook it. In fact, heating to 60 C for 15 minutes will kill ASF.

ASF virus is on the move in other parts of the world. This scares me — a lot.

It has managed to find its way into Eastern Europe and since 2007 has moved through wild boar populations and commercial pig farms in countries like Russia, Ukraine and Poland. In 2018, ASF was identified in wild boars in parts of Belgium and is currently very close to the border with France.

In addition to the ASF threat to Europe, China reported its first case in August of last year.

The Chinese hog industry is large and relatively unstructured, making disease containment very difficult. China now reports 25 provinces with ASF circulating in their swine populations and no sign that it is slowing down.

There are many reasons this virus keeps me up at night.

Once introduced into a population, ASF has been difficult to stop.

Western Canada’s hog sector consists of approximately 600,000 sows and produces more than 15 million pigs on 2,400 farms each year.

We also have more than 2,000 niche market hog producers contributing to the pork meat industry in Western Canada.

Layered into this diverse network of commercial and backyard swine farms is a population of wild or feral pigs across all four western provinces.

At first glance, the connection between these three distinct populations of pigs in Western Canada is not obvious, but when you consider how ASF virus is transmitted, each of these groups pose a risk to the other groups. ASF does not discriminate between the breed or production method — all pigs are susceptible.

Modern commercial pig production relies on a global supply of inputs, including feed ingredients from China. Researchers have established that many foreign animal disease viruses, including ASF, can contaminate feed ingredients, such as soybean meal, and survive container ship transport from ports in China to the United States.

The Canadian Pork Council is recommending pig farms and feed mills hold feed ingredients for 20 days at 20 C before feeding to pigs. While this is challenging during a western Canadian winter, it does provide more time for any virus that might be present in the feed to die off.

Backyard pig producers typically have facilities allowing their pigs access to the outdoors. While this does afford the pig certain liberties, it also exposes them to potential risks, including exposure to wild pig populations.

Farmers must be vigilant in maintaining penning and consider double fence lines to prevent wild boar access to their pig herds.

The risks that feed ingredients pose to commercial farms are similar to those with backyard production. Feed should be sourced from feed mills that have biosecurity policies in place and that can quarantine their ingredients. Avoid kitchen-grocery waste feeding (swill feeding) and never feed meat of any type to pigs.

Travellers pose a foreign animal disease risk to all livestock producers in that their clothing and “souvenirs” brought back to Canada could be contaminated with a pathogen.

Australia has recently reported five instances where confiscated items at airports tested positive to ASF. Fortunately for Australia, those items were destroyed.

For example, travellers bringing back dried cured sausages (illegally) into Canada could be bringing back ASF from affected countries.

Western Canadian pig producers — large or small, commercial or niche market — need to continue to understand their ASF risks and take steps to minimize those risks.

Biosecurity is our best defence against ASF, and I encourage all pig farmers to reach out to a veterinarian to discuss how to best protect themselves. Pig health and welfare in Western Canada depend on it.

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