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Procedures to eliminate H3N2 swine influenza virus from a pig herd
  1. M. Torremorell, DVM, PhD1,
  2. A. Juarez, DVM2,
  3. E. Chavez, DVM2,
  4. J. Yescas, DVM3,
  5. J. M. Doporto, DVM, MSc4 and
  6. M. Gramer DVM, PhD5
  1. 1 Genus/PIC, Suite 2200, 100 Bluegrass Commons Boulevard, Hendersonville, TN 37075, USA
  2. 2 PIC Mexico, Wenseslao de la Barquera 7, Queretaro, Queretaro, 76040, México
  3. 3 Presqueria Norte SN-6 Residencial El Álamo, Colonia Reforma, Navojoa, Sonora CP 85800, Mexico
  4. 4 Departamento de Producción Animal, Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México, Avenida Universidad 3000, Delegacion Coyoacan, CP 04510, Mexico
  5. 5 University of Minnesota Veterinary Diagnostic Laboratory, 1333 Gortner Avenue, St Paul, MN 55108, USA
  1. Room 385, Animal Science/ Veterinary Medicine, University of Minesota, 1988 Fitch Avenue, St Paul, MN55108, USA torr0033{at}


A three-site pig herd infected with a H3N2 swine influenza virus (SIV) underwent a herd SIV elimination programme using herd closure and partial depopulation. The herd consisted of sow, nursery and finishing units, 1 to 2 km apart. Disease was noted in the sow unit and then the nursery unit. The herd temporarily stopped introduction of replacement animals, and replacement gilt introductions in the breeding herd was changed from monthly to quarterly. Gilts from a serologically negative source were also introduced and monitored. Virus elimination from growing pigs was attempted by totally depopulating the nursery and finishing sites once there was evidence that shedding in site 1 had stopped. Sentinel gilts remained serologically negative by haemagglutination inhibition (HI) test (0 of 69 animals negative) for at least 20 months after the initial disease. After restoring the pig flow in site 2, pigs did not experience flu-like clinical signs and HI serology results remained negative (0 of 30 animals tested) for the six months following repopulation of sites 2 and 3. In addition, nursery mortality was improved by 2·2 per cent, the growth rate was improved by 0·123 kg/day and feed efficiency was improved 0·26 points. Based on these results, SIV elimination was considered successful.

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