For years, PIC and others have cited Dr. Derald Holtkamp’s research on the economic impact of porcine reproductive and respiratory syndrome virus (PRRS) on U.S. pork producers. The findings have always highlighted the grim reality of dealing with this devastating disease, but the 2024 results were staggering: PRRSV caused an estimated $1.2 billion per year in lost production in the U.S. pork industry from 2016 to 2020, an 80% increase from a decade earlier. Previously, the estimated annual loss was $664 million.

It’s become clear that the problem is only getting worse, and the industry is in need of a solution.

We recently sat down with Dr. Holtkamp to dig deeper into his research and background and get his take on what the industry can do to combat the growing losses from PRRS.

PIC: Tell us more about your background and what led you to studying PRRS and its economic impact?

Dr. Derald Holtkamp:
In high school I was one of those kids who wanted to be a vet. We mostly had cattle, and I showed cattle, so I aspired to be a large animal vet. But when I got to ISU for undergrad, I took a different path and studied agricultural business and got a Master’s in agricultural economics. Then I changed course and also got my DVM in 1997. As far as I know, I am the only swine vet that has an advanced degree in economics, so I’ve developed this [research] as a niche.

There aren’t many vet colleges that specialize in swine medicine anymore. When I was in vet school at Iowa State University I had some great mentors there.  I also spent a summer at the University of Minnesota, which increased my interested in the swine industry. During my first American Association of Swine Veterinarians annual meeting, I realized I really liked my colleagues and felt that I could spend my career with them.

PIC: What has most surprised you about PRRS and its impact on the pig industry during your career?

Holtkamp:
The most striking thing about the virus is its ability to adapt. Because it’s a single strand RNA virus, mutations happen frequently. More recently, we’ve learned that it has a propensity to create recombinants, which adds a whole new level of concern. It has found a way to thrive in the industry. It’s no coincidence that PRRS became the costliest disease: it’s proven to be very suited for the industry and the large populations we’ve created. We have a very open production system in the sense that we bring things in and out of the farms every day – employees, feed, semen – and we have trucks on the road all the time visiting many sites and creating connections between operations. That makes biosecurity challenging and makes it easy for PRRS to spread from one population to the next.

PIC: The world has evolved since PRRS was first identified in the 1980s. What role have you seen innovation and technology play in the swine industry since then?

Holtkamp:
There have been multiple times where we have come across things that seemed to provide a lot of promise, like executing herd closures and rollovers to eliminate the virus from sow farms without depopulating. There was a lot of excitement, but then new isolates emerged, and eliminating the virus was more difficult. The virus has outsmarted us along the way. Plus, the industry looks very different today than it did in the eighties. Biosecurity, as currently practiced, hasn’t been up to task.

PIC: Obviously, biosecurity is a critical component in protecting against PRRS and other swine diseases. What needs to be done to make biosecurity more effective?

Holtkamp:
Just because we do away with PRRS doesn’t mean we can do away with biosecurity. There are many other pathogens. From my standpoint, the thing we probably do the least well is identify the problems. We tend to jump to a solution. There’s no reflection on ‘is this the best use of time and resources?’ ‘Do I have bigger gaps in my biosecurity?’ Outbreak investigations are a fantastic opportunity to comprehensively to do just that. Outbreaks provide us with an opportunity for a thorough analysis of biosecurity hazards. Then you can decide steps of action. Then, you can sit down and strategize around the priorities so that we can close some gaps. The hazards lie within the production process, like in barn designs, layouts, operational procedures and resources – and each is an opportunity for a gap and a fundamental shift.  

PIC: What do you think about the potential impact of gene-editing technology? 

Holtkamp:
I’ve told this story several times: I remember in 2014, when Randy Prather from the University of Missouri got up and presented all the things they had tried in the last ten years [to address PRRS], and none of them worked. It was kind of a depressing presentation. And I distinctly remember the next year being surprised they had him on the agenda again. I remember it very clearly: he got up and presented that they knocked out the CD163 receptor and found no infection replication and clinical signs of PRRS. I thought ‘oh my, that is something.’

 I was skeptical at first, but it’s really lived up to its promise.

Every active swine veterinarian today has battled PRRS their entire career and arguably with very little success. A lot of researchers have spent a lot of time to understand vaccines and the virus better. But we are at a point where we have to truly nip the disease. When we have a technology like the PRRS-Resistant Pig, we have to pay attention. This may be our shot at being a little smarter than the virus. Of course, anytime there is a new technology, we have to go about it with some caution, but it makes no sense to reject it outright. I think from the standpoint of resources, sustainability and the environmental health of the planet, we have to find a way to reduce some of the inefficiencies that the PRRS virus and poor animal health causes every year.

From a sustainability standpoint, we have to consider using innovations like this to be more efficient about our use of resources. If we have an opportunity to have a lighter footprint on the planet, we should be looking at that very seriously.

One of the things that I have done for the last five years, with agricultural economists Lee Schulz and Dermot Hayes, is a Global Swine Benchmarking project to benchmark financial productivity of swine farms around the world. We look at costs and profitability of producers in 21 countries in Europe, Asia, the U.S., Canada and Brazil. The factors we look at are feed prices, disease and productivity, and we see what difference that makes for producer profitability. In 2022, the superior productivity of Brazilian producers gave producers there a 16 to 18 cents per pound on carcass weight basis advantage over U.S. producers. Why is that and how can the U.S. become more profitable?  My first response is let’s deal with PRRS. We need an alternative to dealing with diseases, and it’s important to look at innovations and to not reject them off the bat

PIC: What should give the swine industry hope as we continue to battle PRRS?

Holtkamp:
We can make more progress with biosecurity. I see us beginning to change our mindset about biosecurity, and I think it’s promising.

I do think the speed of innovation seems to be increasing for opportunities like gene editing and disease-resistant pigs. What gives me hope is that we seem to be coming up with new and novel approaches to managing disease on both the human and animal side. Emerging technologies are potential gamechangers for solving PRRS.  

The reality is if you did away with PRRS, it would have a huge impact on producers and even on consumers.

It would be nice to be able to say that we beat PRRS before I retire.