Despite the rumor mill surrounding the virulent porcine reproductive and respiratory syndrome (PRRS) Lineage 1C strain 1-4-4, Paul Sundberg, DVM, says it’s not time to sound the alarms yet. It is important to put this strain in perspective and look at the bigger picture.
“It’s no doubt an issue, but in the big picture, there’s no indication PPRS is burning down barns across the country. We’ve got to keep that in mind,” says Sundberg, who is the executive director of the Swine Health Information Center (SHIC).
This particular variant of PRRS can be extremely virulent, almost to the point where if you get it, you will know it immediately, he says.
“Reports from veterinarians are that it hits so hard,” Sundberg says. “Your pigs get sick – all ages, even resulting in mortalities in sows. Other strains may be more prevalent, but this particular Lineage 1C strain of 1-4-4 is extremely virulent throughout the production cycle.”
It’s typical for PRRS outbreaks to flare up throughout the country from October through March when barns close up. Reports from the field, however, indicate that this strain is a fairly regional outbreak, he says.
“The classification of PRRS 1-4-4 is a widespread virus, but this is a very specific variant within that classification. It looks like it’s showing up in the upper Midwest,” Sundberg added. “Reports of it started increasing in December and as far as we know, right now, it’s still localized in the Midwest.”
Veterinary diagnostic lab reports showed testing for PRRS came back positive about 28% of the time in December 2020, Sundberg says. In February 2021, tests are coming back positive for PRRS about 26% of the time. Although it may not be statistically significant, he says PRRS testing isn’t increasing, suggesting that there are not a lot of new outbreaks. He notes levels are comparable to what’s expected for this season.
“Right now, Indiana, Ohio, Nebraska are having outbreaks of PRRS, not necessarily of this Lineage 1C 1-4-4 variant, but they’re having outbreaks of PRRS higher than other states. Again, that’s a seasonal issue. I think it’s something that is not out of line with what we’d historically expect,” Sundberg says.
Putting the 1-4-4 strain of the virus in perspective with other viruses is key right now.
“We deal with PRRS a lot in the U.S., but there are other more prevalent PRRS viruses out there that cause problems. This one is more virulent, but we don’t really know exactly how it’s going to act in a timeline compared to other viruses,” Sundberg says.
Reports indicate so far that this strain will go through a production system for two to three weeks. Eventually, the farm will be able to work its way out, stabilize the herd and start to reintroduce some breeding animals, he explains.
“I’m not so sure that there’s alarms needed yet,” Sundberg says. “In talking to veterinarians working through herd closure, stabilization of the herd is probably the most effective thing that we can do once we get it.”
But Sundberg is quick to point out that the pork industry should always raise alarms about biosecurity.
“You can go through a long list and talk about different steps in biosecurity and what you should do, but one of the most important things to do is to make sure your biosecurity plan is being consistently implemented. It’s easy to put it down on paper, it’s harder to make sure it’s happening every day,” he says.
In order to prevent and control this virus – to maintain it into a controllable area where it can burn itself out – biosecurity is extremely important.
“It’s not just about biosecurity on the individual farms, but in the regions as well,” Sundberg says. “Biosecurity should be a wake-up alarm every day as we go through our business.”
Read more from Dr. Paul Yeske’s experience in the field:
PRRS Strain 1-4-4: The Most Dramatic Strain I’ve Seen, Yeske Says
