Thursday, February 8, 2007

K-State Study Finds New Vaccine Effective Against Deadly Viral Disease Affecting Swine Herds in Kansas

By Brennan Engle

Researchers from Kansas State University's College of Veterinary Medicine have completed a study showing that a newly-developed vaccine is effective against a deadly viral disease that is affecting swine herds in Kansas.

The disease, most widely known as porcine circovirus associated disease, was first recognized in Kansas swine herds in November 2005. The disease complex is an immunosuppressive condition associated with porcine circovirus type 2 or PCV2.

Clinical signs of the disease in pigs include extreme and sudden weight loss, immune suppression, labored breathing, jaundice and diarrhea. More severe cases of the syndrome are characterized by skin lesions, neurological deterioration, kidney failure and eventually death. Swine producers with infected herds have experienced a death loss of 20 percent to 40 percent in finisher pigs, which are pigs between 10 weeks to 20 weeks of age. This has resulted in a devastating economic loss.

The researchers began a field trial in summer 2006, testing a vaccine in commercial development. The researchers, all from the department of diagnostic medicine and pathobiology, were Bob Rowland, Dick Hesse, Steve Dritz, Jerome Nietfeld and Kyle Horlen. The field trial, directed by Dritz and Horlen, was conducted on a family-owned swine farm in northeast Kansas and concluded in January with promising results.

The study showed a 50 percent reduction in mortality of vaccinated pigs compared to non-vaccinated pigs. Mortality was 7 percent for vaccinated pigs compared to 17 percent for non-vaccinated pigs. Vaccinated pigs also experienced an increase in growth. On average, they were 20 pounds heavier than non-vaccinated pigs of the same age.

"Results from this study suggest that the tested vaccine is effective in controlling the PCV2 associated disease in pigs," said Rowland, a virologist and associate professor of diagnostic medicine and pathobiology.

The researchers recommend producers who suspect their pigs are experiencing a porcine circovirus type 2 associated disease outbreak contact their veterinarian to confirm the diagnosis and then acquire the vaccine, which is now available commercially.

"We want to make it clear to swine producers that this vaccine licensed by the U.S. Department of Agriculture's Center for Veterinary Biologics is safe and effective," Rowland said.

Disease associated with porcine circovirus type 2 was first identified in Canada a decade ago and later appeared in Europe. It has become widespread and is in most pork producing areas of the United States. Reports from other countries confirm that it is also becoming prevalent throughout the world.
Steve Henry, a swine veterinarian from Abilene and an adjunct professor of diagnostic medicine and pathobiology at K-State, is working closely with the research team. Henry said that it remains a mystery how the circovirus spreads. He said outbreaks have occurred rapidly, yet randomly in swine operations with the highest levels of biosecurity protocol.

"It makes control strategies like quarantine practically irrelevant if the virus can bypass the barriers," Henry said. "This is not a classic outbreak, in which the initial occurrence is followed by the ripple effect, spreading out from a source point."

While the results of this clinically significant project are encouraging, there are many questions about this emerging disease still facing K-State scientists. A special fund has been established for donations to further immediate research on porcine circovirus associated disease