The Swine Health Monitoring Project at the University of Minnesota has provided an update on a study of lateral spread of porcine epidemic diarrhea (PED) virus, focusing on a preliminary report from North Carolina.

Some 155 PED virus positive sites in the state are participating as case farms in a larger cluster analysis to identify risk factors for lateral spread of the virus. The case farms are matched to two negative controls and given a biosecurity questionnaire to compare potential risk factors between cases and controls.

Data from the first 17/47 questionnaires include eight positive and nine negative sites that showed:

  • Positive sites had average herd size of 4,683 vs. 4,035 for negative sites.
  • Positive sites were in more dense regions than negative sites.
  • Positive sites had approximately double the frequency of feed truck deliveries compared to negative sites.
  • Positive sites had approximately double the frequency of trucks visiting to remove pigs of any age than negative sites.
  • There were 40% more farms in the positive group that had culls removed from the site in two weeks preceding infection.

Spatial analysis indicated that:

  • Cases immediately following previous infections occurred directionally at 20 degrees northeast on average.
  • Odds of being infected with PED virus were 8.4 times greater within one mile of an infection, 6.3 times greater if located within two miles of an infection, but no greater if within three miles.
  • Sites with sows and grow-finish pigs had the highest incidence of PED virus.
  • Site capacity was not significantly associated with PED virus.

Project coordinator is Dane Goede, a PhD graduate student at the University of Minnesota Veterinary Population Medicine. He can be reached at goed0051@umn.eddu.