This winter is the key to the future of the pseudorabies (PRV) program, says Paul Sundberg, DVM, National Pork Board assistant vice president for veterinary issues.
If the pork industry can duplicate last winter's good fortune of dodging a major PRV outbreak, there's a good chance that eradication can at last be achieved, he says.
The federal-state-industry PRV eradication program, which began Jan. 1, 1989, has been a display of unprecedented cooperation in swine disease eradication.
PRV has cost pork producers over $30 million annually in production losses and access to foreign markets.
Despite the fact only a handful of PRV-infected herds remain in Iowa and Nebraska, risk of an outbreak still exists, suggests James D. McKean, extension swine veterinarian at Iowa State University.
“There is fair evidence that we don't have all the virus out even in some areas where it is thought there aren't any infected herds,” he says. “We continue to find a few newly infected herds in areas that we thought were negative for the disease,” adds McKean.
McKean and Sundberg both agree, however, the biggest concerns are if at-risk herds don't vaccinate this fall and winter and use proper biosecurity.
“We have a large number of naïve, at-risk pigs out in the countryside, and any pseudorabies virus (PRV) that could get into that area would be like throwing a match into a pile of dry leaves,” declares Sundberg.
He strongly advises producers to consult with their veterinarians regarding timing and vaccine dosage regimens that are necessary to get through this critical time period.
For sure, breeding herd and finishing hog vaccination programs should continue, says Sundberg. “A common mistake is to vaccinate feeder pigs too early while they still have maternal immunity. The vaccination either doesn't take or it is at such a low level that as those pigs get to be 5-6 months old, they don't have any protection anymore,” he says.
Maternal antibodies for PRV last 10-12 weeks. Common practice is to move nursery pigs to the finisher at about eight weeks of age. But vaccinating them at that time may not be effective, warns Sundberg.
Producers should vaccinate pigs on arrival if their operation is in a pig-dense area at risk to PRV infection, says Sundberg. That advice also applies to naїve, imported Canadian feeder pigs.
USDA's Accelerated Pseudorabies Eradication Program offers assistance to purchase vaccine through the states. Producers should contact their state veterinarian for information.
Biosecurity issues for PRV are the same as they would be for many other diseases. Pay attention to people and pig contact, traffic patterns in and around the farm, says Sundberg.
Transportation may be one of the missing links in farm biosecurity programs. “It is interesting that people will require 48 hours away from pigs for visitors, make them shower and put on clean clothing, then turn right around, have a trucker back up to a loading dock, get off and walk into a pig facility,” charges McKean.
The “meat juice” program pilot tested at three Iowa packing plants has been successful in detecting infected sites not picked up in down-the-road herd testing or sow cull testing programs, explains McKean. From March through June 2001, there were 40 new infections detected in Iowa. About a third of those cases were found using the meat juice test at slaughter plants.
Traditionally slaughter plants focus on taking serum samples of culled breeding stock, says McKean. There is no program to test market hogs for PRV because kill line speeds make it dangerous and difficult to perform serum testing.
The growth of multi-site operations has expanded the number of separate finishing sites and increased the risk of PRV infections in finishing hogs.
That concern resulted in startup of the meat juice testing program. Using technology developed in Europe, normal fluids contained in muscle samples can be collected and tested for PRV after animals are slaughtered, explains McKean.
The testing approach is being expanded to all eight packing plants in Iowa until June 2002. “We hope that it will provide an early warning system in case there is a PRV flareup,” he says.