Porcine Reproductive and Respiratory Syndrome

VIRUSES ARTERIVIRIDAE

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