Progress after one year of a pseudorabies eradication program for large swine herds.
Six large farrow-to-finish swine herds quarantined for pseudorabies in Illinois participated in the USDA-initiated Large Herd Cleanup Study. These herds were monitored for antibodies to pseudorabies virus (PRV) for 1 year after the initiation of an intensive eradication program. Herd size ranged between 425 and 1,500 females of breeding age. Gene-deleted modified-live virus vaccines were used on all farms, with 3 of the 6 herds receiving a vaccine with a deletion of the gene for glycoprotein-I and the other 3 herds receiving a vaccine with a deletion of the gene for glycoprotein-X. The breeding herd and growing pigs were vaccinated on each farm. Each herd produced its own replacement gilts. In addition, management changes emphasizing all-in, all-out pig flow were initiated. One year after initiation of the vaccination program, sera for the measurement of PRV antibodies were obtained from sows and heavy finishing pigs (> 70 kg) from each of the farms. Prevalence of PRV antibodies attributable to wild-type virus infection ranged from 7 to 63% (median, 33%) for sows and from 0 to 42% (median, 4%) for finishers, as determined by the appropriate vaccine differential test. For each sow herd, there was a large decrease in the PRV seroprevalence rate after 1 year of the program (range, -21 to -68%; median, -42%). Examination of PRV prevalence rates by parity indicated decreased seroprevalences in the lower parities (< 2) in 3 of the herds, suggesting that vaccination reduced the spread of PRV.(ABSTRACT TRUNCATED AT 250 WORDS)
Lehman
J R
JR
Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois, Urbana 61801.
Weigel
R M
RM
Siegel
A M
AM
Herr
L G
LG
Taft
A C
AC
Hall
W F
WF
D000818:Animals; D000914:Antibodies, Viral / Q000097:blood*; D005260:Female; D005500:Follow-Up Studies; D011558:Herpesvirus 1, Suid / Q000276:immunology*; D007087:Illinois / Q000453:epidemiology; D008297:Male; D010298:Parity; D015995:Prevalence; D011557:Pseudorabies / Q000453:epidemiology / Q000517:prevention & control*; D013552:Swine; D013553:Swine Diseases / Q000453:epidemiology / Q000517:prevention & control*; D014765:Viral Vaccines
D000914:Antibodies, Viral; D014765:Viral Vaccines