Herd Health: The PRRS eradication campaign is finally underway!

Thursday, June 10, 2010

A number of U.S. jurisdictions are launching area regional control projects which offer the hope of eliminating this hugely costly disease. And Canadian provinces are expected to follow suit

by S. ERNEST SANFORD

The countdown to eradication of Porcine Reproductive and Respiratory Syndrome from the United States, and indeed all of North America, has started. Plans are being laid out, details organized and the momentum is growing. The industry is gearing up for action against PRRS.

Some time in the summer of 2009, the idea of eliminating PRRS from the U.S. swine herd got rolling. It seems to have started during a brainstorming session between Drs. Tim Loula of the Swine Veterinary Center in St. Peter, Minn., and Joe Connor of the Carthage Veterinary Service in Carthage, Ill. However, it could be argued that it actually got started in March 2007 at the annual meeting of the American Association of Swine Veterinarians (AASV) in Orlando, Fla., when Dr. Scott Dee, then president of the AASV, drew a line in the sand and set a target for the eventual elimination of PRRS over a 20-year period. Fast forward to summer 2009, the middle of the huge swine industry downturn, and Drs. Loula and Connor decided: "Why don't we get rid of PRRS?"

The fact is that the industry is tired of PRRS. It beats us up.  It wears us out.  PRRS costs the U.S. swine industry $560 million a year. Over the 20-plus years we've been battling PRRS. that amounts to $11 billion.

At the Leman Swine Conference in September 2009, Dr. Dale Polson pointed out that the U.S. swine industry is worth more than $12 billion a year. He then equated the negative hit of PRRS as being equal to the United States not producing a single pig for an entire year. These are big dollar figures and hard to grasp in everyday parlance.
To bring it home more clearly, $560 million a year means that PRRS is costing the U.S. industry more than $1.5 million a day, every single day. And it has been doing so for over 20 years!

So, how do we get rid of PRRS?  We've had the knowledge and know-how to do so for more than a decade. The problem has not been getting rid of PRRS, but stopping the virus from coming back into a herd after it has been eliminated, especially by aerosol means in pig-dense areas. The addition of air filtration to barns might just be the last step in preventing re-infection. This final step also seems to have galvanized veterinarians into making a push towards eradicating PRRS. 

Instead of eliminating the virus from a herd here and there, it has become increasingly obvious that a more concerted, co-ordinated approach is necessary. Thus was born the concept of area regional control (ARC) for PRRS. There have been several ARC projects started in recent years with varying degrees of success. One of the earliest and most publicized was the Rice County project in Minnesota.

This project ran successfully for more than four years, but finally foundered last year. Dr. Bob Morrison of the University of Minnesota, who led the Rice County project, told the 2009 Leman Swine Conference that failure was due to the lack of unified local veterinarian and producer leadership, and a large, influential producer being unwilling to try herd closure and eradication.

The most impressive ARC project so far has been the Stevens County project in Minnesota. Stevens County is a relatively pig-dense county in Southern Minnesota, surrounded by seven counties with low pig density. Fortuitously, the pig population in Stevens consists of several breeding stock companies. Of 89 herds in Stevens, 33 were breeding stock herds. The net result is that most pigs leave the county and few pigs enter Stevens. 

For the first two years, the Stevens County project was funded by the county's producers, with no external financing. Co-operation among veterinarians and producers, University of Minnesota researchers and industry personnel brought it to its current state, which is that all but one of the herds are now PRRS-free. Efforts are being made to have that single standout herd come in line with the rest of the county.

With Stevens County completed, the expectation is that the eradication movement will advance into the seven surrounding low-density counties, and this is now happening.

A number of other ARC projects are also underway:
•    In December 2009, all of Minnesota, north of Highway #212 was officially declared an ARC target for PRRS elimination.
•    Once the Northern Minnesota ARC is established, it is proposed that it be extended into the neighbouring states of North and South Dakota.
•    Led by Dr. Dyneah Augsburger of the Carthage Veterinary Service, a three-county region in Illinois, consisting of Hancock, Adams and MacDonough counties, is now being organized as an ARC project.
•    In Michigan, a two-county region with Lake Michigan as a border is the focus of an ARC, co-ordinated by Dr. Barb Straw of Michigan State University.
•    Indiana, Pennsylvania, North and South Dakota are all in the process of organizing their own ARCs. An ARC in the state of Sonora, Mexico, started by the late Dr. Carlos Pijoan, failed in the last decade due to lack of local support and because the organizers were all from outside the area, mainly from Minnesota. In 2009, however, the Sonora producers organized themselves and approached Dr. Laura Batista, who was then working and living in Quebec, to lead them in a renewed ARC effort.
•   In Canada, it can be expected that ARCs will be considered in Ontario, Quebec and the western provinces.

In the meantime, clearly defined steps for starting and conducting an ARC have been established and form a template for any group starting an ARC.
•    A feasibility study should identify an area suitable for an ARC and assess which producers and veterinarians are willing to participate. The study should also determine how many herds are in the ARC area.
•    Confidentiality issues should be investigated with study partners and appropriate forms for signature developed.
•    Producers, service providers and participating veterinarians in the ARC area should be educated to develop buy-in and get the project started.
•    A PRRS risk assessment should be undertaken to determine internal and external risks for spread of the PRRS virus between herds and within each herd.
•    Diagnostics should be done to determine the PRRS status of herds within the proposed ARC zone.
•    PRRS control strategies should be designed, using resources already available across the industry.
•    Quarterly kitchen table meetings should be held to go over progress, problems, bottlenecks and provide updates.
•    Ongoing PRRS monitoring protocols should be set and execution ensured.
•    Regular updates and annual or semi-annual progress reports should be presented to the industry at large.

So the PRRS eradication drive has started. Over the winter, several U.S. pork producer associations are expected to pass formal resolutions of support, including financial backing, for ARC projects within their states. I shall continue to report progress on the various ARC projects over time. BP

S. Ernest Sanford, DVM, Dip. Path., Diplomate ACVP, is a swine specialist with Boehringer Ingelheim Vetmedica (Canada) in Burlington. Email: ernest.sanford@boehringer-ingelheim.com