Pennsylvania officials are requiring that 18,000 hogs from farms in south-central part of the state be slaughtered in order to contain a pseudorabies outbreak.

The virus has been detected on hog farms in Adams, Berks, Lancaster, Lebanon and York counties, but appears to be under control, state veterinarians report. Farms adjacent to those where animals tested positive have been quarantined, says John Enck, director of the state Bureau for Animal Health and Diagnostic

PRV spreads between animals through nose-to-nose contact and can spread between farms and herds on boots, clothing, feed or farm equipment. In the federal fiscal year ending Sept. 30, 2002, about 125,000 swine in 10 states – nearly half of those in Iowa – were slaughtered because of exposure to PRV, according to USDA figures. That's down from 335,515 hogs slaughtered in 2000. Another 11,800 hogs were slaughtered between Oct. 1, 2001, and mid-April 2002, reports USDA.

Enck says animals involved in this recent outbreak didn't show any clinical signs. The virus was detected in mid-July in a sow sent to slaughter and traced back to a company that contracts out production with various farms. Most hogs believed to have been exposed to PRV were slaughtered three weeks ago. The remaining 800 were to be slaughtered Thursday, says Enck.

USDA epidemiologists are examining records of the outbreak to determine how the disease entered Pennsylvania. Enck says, the virus likely entered the state via one or more hogs imported from another state. About 25 percent of pigs entering the state are tested for the disease, but most hogs that go directly to slaughter are not
tested, he says.

Pennsylvania's last PRV case was detected in 1998. The infected farms are to be disinfected and left vacant for 15 days. Adjacent farms will be tested over the next three months to monitor for the virus.

The U.S. pork industry has a PRV eradication program that has made great strides in reducing the number of PRV infections across the nation.
The sow-slaughter PRV-testing program is part of the overall surveillance efforts.

USDA, Pennsylvania State Animal Health Department.