Veterinarians agree: The time has come to test the feasibility of eradicating porcine reproductive and respiratory syndrome (PRRS) on a regional basis.
Paul Yeske's plight typifies the struggles facing many swine veterinarians trying to wipe out the PRRS virus.
Yeske says viral sequencing proves that depopulation-repopulation has eradicated PRRS from herds in his St. Peter, MN, practice that includes many hog-dense areas in Minnesota and Iowa.
“We have gone back and made sure that PRRS breaks weren't the original viruses present on the farm,” he explains. “In 12 months' time, we are at over 80% survival rate of farms. In most cases, 12 months will return the cost of depopulation.
“As you get out to 24-months plus, we are at about 45% survival. And that is one of the reasons we have started thinking that we have got to work more on a regional basis and not just on a herd level, because too many of these herds are failing over time,” he stresses.
Using a computer database, Yeske's practice has developed maps that pinpoint some of their clients' PRRS-positive and PRRS-negative herds. The visual perspective has helped convince him to avoid PRRS eradication efforts in areas where there are simply too many positive/infected herds.
Using the maps, staff has gone into some operations and switched outside pig sources in order to protect the integrity of some very key PRRS-negative regions, he says.
Yeske believes that area eradication of PRRS is possible, provided the effort starts in areas of low prevalence.
County Eradication Project
A pilot project to evaluate the feasibility of an area-based eradication plan began in March 2003 in eastern Rice County, directly south of the Twin Cities (MN).
The first set of objectives were to pinpoint the prevalence of PRRS and to gain the support of area producers, says Mike Strobel, DVM, Northfield, MN, project coordinator. Those two objectives have been met, and alliances have been forged among local veterinarians and producers to work toward elimination of the virus. The project area involves four veterinary clinics in a 60-mile area.
Since a major source of PRRS virus within a region is its sow herds, the first action will be to stabilize them. The region includes 11 sow herds, five of which are positive for PRRS. Strategies include inoculating gilt replacements with serum containing PRRS virus present in the herd, or using PRRS modified-live-virus vaccine in gilt replacements and in a whole-herd, quarterly vaccination program.
A second action is voluntary, area-spread control using monitoring tests and developing a uniform approach to the PRRS problem, says Strobel.
A third action is implementing uniform education of all producers for a consistent approach to eradication.
The growing number of outside sources supplying pigs and breeding stock to Minnesota is another concern. In the last 12 months, Minnesota imported 4.8 million feeder pigs and 99,000 head of breeding stock, and the numbers grow each year, reports Paul Anderson, DVM, Minnesota Board of Animal Health.
Call for Unity
University of Minnesota swine veterinarian Scott Dee calls for unity, urging his peers to “unite in a common goal to change our attitude and mindset on how we deal as an AASV (American Association of Swine Veterinarians) membership with this disease (PRRS).”
Dee says, “PRRS is sinking our industry because we have been fighting each other at the same time we have been fighting this disease.”
He calls for the AASV to work as a team “to eliminate this virus from the top down of the organization.” Dee is currently the vice president of the AASV.
He suggests a four-point plan:
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Disclosure and transparency throughout the membership. “We need membership-wide disclosure of our funding origins and income streams.”
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Building a team. “We are not going to have success working as individuals.”
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Development of new research models. “We need new infectious disease models with large populations of pigs under controlled field conditions to bridge the gap between traditional research facilities and the real world.”
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Fostering of a regional mentality to PRRS eradication. Dee says the industry has the tools for regional control and eradication of PRRS. All that is missing is the spirit of cooperation.
