Hog farmers find themselves in the time of year when cases of porcine reproductive and respiratory syndrome (PRRS) tend to ramp up across the country.

But, there are steps producers can take to reduce the risk of an outbreak on their farms, according to experts during a recent webinar hosted by the National Pork Board (NPB).

Such preparations would be particularly helpful coming off a year that featured significant outbreaks of PRRS 1-4-4 lineage 1C, a new variant that wreaked havoc on the industry.

“It all started with growing pig barns. Pigs were becoming really sick. Then, we started seeing something similar in breeding herds,” said Cesar Corzo, associate professor in the Department of Veterinary Medicine at the University of Minnesota.

Corzo is involved with the Swine Health Monitoring Project, which receives weekly health updates on swine farms from 38 companies.

“We could see (the new PRRS strain) was spreading rapidly,” he said. “Some farms were heavily impacted (with mortality rates in the breeding herd as high as 40%).”

The first PRRS 1-4-4 wave broke out in the fall of 2020, followed by a second wave. The virus may have reached about a quarter-million sows and half a million pigs in the monitoring network, with most cases clustered in southern Minnesota and northern Iowa.

Cases spread to surrounding states as well, including Illinois.

Pat Bane, a member of the NPB board and McLean County Farm Bureau, endured two rounds of PRRS outbreaks in 2020 that forced him to depopulate his herd.

“It was devastating to say the least,” Bane recently told FarmWeek. “It was clearly the worst year we ever had.”

Corzo said there’s no single factor that caused the prolific PRRS outbreak last year. But he explained why it was so devastating to some herds.

“Every year, we see an increase of cases reported in October and November. But then we saw another epidemic, telling us this virus was behaving differently,” Corzo said.

“We know these viruses tend to evolve,” he continued. “With every new strain that emerges and goes into the population, there’s not enough immunity.”

What can farmers do to boost the biosecurity on their farms? Lisa Becton, director of swine health, information and research at NPB, advises farmers to take the following steps during this critical time of year:

  • Look at manure management practices that may lead to risk of spreading viruses.
  • Create a line of separation between caretakers and pigs from everything else entering the farm, with a goal to keep the pigs and farm separate from outside risks.
  • Spread manure only in pre-determined areas. Application workers should not enter the farm.
  • Disinfect equipment, particularly when moving from farm to farm.

“This is the time of year people are out and active,” Becton said. “Make sure biosecurity needs remain at the forefront.”

Scott Dee, veterinarian with Pipestone Veterinary Services, said recent PRRS modeling shows it can be spread by contaminated feed, manure and by people and animals. The modeling also shows the use of filters and shower-in/shower-out protocol are very effective to reduce the transmission of viruses.

“Biosecurity protocols work,” Dee said. “We can handle this virus, coming into PRRS season. I have no doubt about that.”

In 2020, U.S. hog farmers marketed more than 131 million pigs despite all the challenges, which provided total cash receipts of more than $19 billion and more than 28 million pounds of meat to consumers worldwide, according to NPB.

Visit the website, porkcheckoff.org, for more information.