Animal health matters: What if African Swine Fever found its way here already?

Russ Daly
Special to the Farm Forum

Swine producers and their veterinarians just got a little more worried.

African Swine Fever, one of the most dreaded foreign pig diseases, was found a little bit closer to our shores. Since ASF exploded in China three years ago, we’ve kept a wary eye on its spread through Asia. So far, we’ve taken some comfort knowing that the disease was still essentially a world away. 

A couple weeks ago, however, ASF was found in a Western Hemisphere country — the Dominican Republic. The risk of ASF reaching U.S. pigs seemingly increased overnight, as the small country is not even 700 miles from U.S. shores (shorter than the distance from Brookings to Bozeman).

African Swine Fever is a dreaded disease for good reasons. The virus causing ASF is extremely contagious between pigs. What’s more, the virus can hang around for long periods of time in pens, barns and trucks. It isn’t killed by many disinfectants. 

Once infected, pigs can die a rapid death, face lingering chronic health problems and everything in between. As such, ASF can devastate individual pork operations and the industries they comprise. Once a country identifies ASF within its borders, its pork export market stops cold. Massive pig depopulation (as the Dominican Republic is doing now) is the common response. 

One good thing about ASF is that it doesn’t affect people — it’s strictly a pig disease.  Pork, even from pigs carrying the virus, is completely safe to eat. What then, is the problem selling it to other countries? The very hardy virus can survive for a long time in frozen or fresh pork and even sausage and some other cured pork products (not after cooking, though).  

Luckily, for many years — and for different pig disease reasons — we have forbidden any pigs or pork products coming to the U.S. from the Dominican Republic. Additionally, the fact that the Dominican Republic is on an island (and, that to my current knowledge, pigs are unable to swim 700 miles) helps.     

But those restrictions just cover the standard pig- and food-related ways that ASF could move from there to here. What about people movement? It’s conceivable a person spending time with pigs could carry the virus to the U.S. on their clothes or shoes during their plane or boat ride.

It’s expected that the Dominican Republic will welcome 5 million visitors in 2021 — 70% of them Americans. Luckily, most tourists don’t put hog farms on their vacation itineraries. But the more travelers, the higher the risk. 

The ability of the ASF virus to survive in pork products is the kicker though. On average, our U.S. Customs and Border Patrol seizes 3,000 different illegal plant and food items — including pork — at our ports of entry every day.

And they’re probably not catching it all.  Scraps from one of those illegal meals tossed in a bin and subsequently fed to pigs would be all it takes to get an ASF outbreak started in the United States. 

Those scenarios seem far-fetched. Most pork-smuggling travelers will never see a pig in their lives, let alone toss their scraps into a pig pen. Any waste from cruise ships or planes that could be fed to pigs is required to be cooked to a virus-killing temperature first. The way we raise most hogs today precludes their contact with visitors and feed that’s not corn- and soybean meal-based. 

Could the ASF virus already have shown up on U.S. soil? It’s sure possible that the virus was carried on a traveler’s shoes, or in a chunk of smuggled pork sausage at some point over the years.  But it hasn’t infected our pigs because so many other things were done right: international travelers were questioned about farm visits upon their return, or food-sniffing beagles at the airport did their job right. Because of these firewalls, the risk of ASF introduction might not be any different whether the virus is in China or our own hemisphere.    

But others need to do things right, too: pork producers should restrict access to their hog barns and question their feed suppliers; veterinarians should stay vigilant for unusual signs of illness in the pigs under their care, and veterinary labs should gear up for testing. 

If ASF is to stay out of the U.S., all of these different people and processes have to get things right — 100% of the time. 

Russ Daly, DVM, is the Extension Veterinarian at South Dakota State University.  He can be reached via e-mail at or at (605)688-5171.