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Outbreak of avian influenza H7N3 on a turkey farm in the Netherlands
  1. F. C Velkers, DVM1,
  2. A. Bouma, DVM, PhD1,
  3. M. G. R. Matthijs, DVM1,
  4. G. Koch, PhD2,
  5. S. T. Westendorp, DVM3 and
  6. J. A. Stegeman, DVM, PhD1
  1. 1 Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, PO Box 80.151, 3508 TD Utrecht, The Netherlands
  2. 2 G. Koch, PhD Section for Notifiable and Exotic Animal Viral Diseases, Wageningen University and Research Centre, Central Institute for Animal Disease Control — Lelystad, Lelystad, The Netherlands
  3. 3 S. T. Westendorp, DVM, Veterinary Practice, ‘Tussen Mark en Amer’, Hooge Zwaluwe, The Netherlands
  1. Dr Westendorp's present address is Poultry Practice, ‘West Nederland’, Den Hout, The Netherlands


This case report describes the course of an outbreak of avian influenza on a Dutch turkey farm. When clinical signs were observed their cause remained unclear. However, serum samples taken for the monitoring campaign launched during the epidemic of highly pathogenic avian influenza in 2003, showed that all the remaining turkeys were seropositive against an h7 strain of avian influenza virus, and the virus was subsequently isolated from stored carcases. The results of a reverse-transcriptase pcr showed that a h7n3 strain was involved, and it was characterised as of low pathogenicity. However, its intravenous pathogenicity index was 2·4, characterising it as of high pathogenicity, suggesting that a mixture of strains of low and high pathogenicity may have been present in the isolate. The outbreak remained limited to three farms.

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