PRRS Risk Assessment Tool measures the level of risk that a PRRS outbreak will occur and provides a complete database featuring benchmarking and analysis.

While several methods have eliminated porcine reproductive and respiratory syndrome (PRRS) virus, success in applying biosecurity measures to keep the virus out following elimination has been inconsistent and unpredictable.

What is hoped, however, is that the PRRS Risk Assessment Tool program coordinated by Derald Holtkamp, DVM, Iowa State University (ISU), will distill down the increasing list of biosecurity practices into a handful that are truly significant for producers and veterinarians to focus on.

From trailer baking to work on insects, fomites and air filtration systems on hog barns, the pork industry has been prolific in turning out new biosecurity research for the industry to consider adding to its arsenal of tools to stop PRRS transmission.

But the challenge now is to eventually focus on what's really significant to stopping the spread of the PRRS virus. “This program is really about applying epidemiology to swine production and identifying the risk factors that contribute to PRRS breaks on hog farms,” he adds.

A pilot study using the PRRS Risk Assessment Tool “was very encouraging,” Holtkamp says. Farms that had a high risk of introduction of virus from an external source broke early with PRRS, while farms with low external risk stayed naïve for PRRS a lot longer.

Four PRRS Studies

That has led to four studies being funded to use the PRRS Risk Assessment tool to more accurately pinpoint the most important biosecurity risks for PRRS infection:

  • Quantifying risk and evaluating the relationship between risk score and PRRS-negative herd survival, as part of the USDA-funded PRRS Coordinated Agricultural Project, coordinated by researchers from Iowa State University and the University of Minnesota.

  • An industry education study for understanding the risk factors associated with PRRS virus breaks in negative or naïve breeding herds funded by the National Pork Board and coordinated by researchers from Iowa State University and the University of Minnesota.

    “Those two studies are basically survival analysis pig studies,” Holtkamp explains. “How long do negative or naïve herds survive without PRRS breaks?”

  • A cross-sectional study of PRRS virus positive swine breeding herd sites to evaluate associations between risk factors and a case definition-based number and severity of clinical PRRS episodes, funded by Boehringer Ingelheim Vetmedica, Inc (BIVI), led by Holtkamp.

    This third study seeks to help improve our understanding of what factors and conditions contribute to some farms having a large number of severe PRRS breaks while others have few, and therefore, provide insights on how to better manage and control PRRS, he says.

  • Developing PRRS control strategies by understanding how the virus is changing and moving in Ontario, funded by the Ontario Pork Industry Council. This study expands on earlier research on a PRRS regional eradication project started in the province.

Value of Biosecurity

“Biosecurity is more significant in trying to deal with PRRS than it has been for other diseases,” Holtkamp suggests. “The tools we have right now for biosecurity have got to be a big part of the arsenal if we decide to eradicate the disease.”

So far the risk assessment tool has focused on biosecurity for the breeding herd. In the future, its use will be expanded to other production phases and other diseases.

Use of the tool is limited to veterinarians who are members of the American Association of Swine Veterinarians (AASV) and who have successfully completed a training session. To date, 92 AASV members have been trained to use the tool and 454 breeding herd assessments have been completed.

The risk assessment is currently an Excel spreadsheet-based tool. A web-based version is expected to launch later this summer, says Holtkamp. The web-based version will provide risk benchmarking reports to veterinarians.

Development, Rollout

The risk assessment tool was developed by BIVI in mid-2003. In March 2005, BIVI offered to gift the tool to the AASV. In March 2006, the AASV, with support from the National Pork Board and USDA, accepted the gift. BIVI continues to provide in-kind support.

In September 2006, ISU's College of Veterinary Medicine entered into an agreement with AASV to establish a Disease Risk Assessment Program to develop, manage and promote disease risk assessment tools and databases of completed risk assessments held by AASV.