Porcine Reproductive and Respiratory Syndrome

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Antigenicity

  • Isolates vary in virulence
  • Some are subclinical

Hosts

  • Pigs: aka Blue Ear or Lelystad virus

Pathogenesis

  • Infects alveolar macrophages, followed by interstitial pneumonitis
  • Persistent infection of Monocytes followed by leukopenia and thrombocytopenia
  • Mostly affects piglets
  • In adults, cyanotic appearance due to vascular lesions
  • Transplacental spread leads to abortion, mummification, or resorption

Epidemiology

  • Discovered in Holland in 1990
  • Highly contagious
  • Survives well on fomites
  • Transfer may also be aerosol or via semen
  • Exacerbated by immunosuppression (eg by porcine circovirus 2)

Diagnosis

  • Clinical signs:
    • Thumping respiration
    • Abortions
    • Flushed skin
    • Eyelid oedema
    • Weak or dying piglets
  • ELISA for virus antibody
  • Rising antibody titres as a retrospective diagnosis (4X increase)

Control

  • Certified Specific Pathogen Free units exclude by quarantine
  • Management: all in/all out, screening AI semen
  • Vaccine available