Porcine Reproductive and Respiratory Syndrome

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Also known as: PRRS, blue eared pig disease

Description

  • The syndrome is caused by a small enveloped RNA virus which belongs to the new Arteriviridae group
  • Replicates in and destroys macrophages and endothelial cells causing vasculitis -> viraemia -> virus shedding (nasal secretions, faeces)
  • Clinical signs: respiratory and reproductive failure, weaned pigs, tachypnoea, eyelid oedema, conjunctivitis
  • Moderate to severe interstitial pneumonia in the cranial lobe
  • Superimposed bacterial infections are common
  • Infectious disease in swine that emerged 10 years ago
  • Today, PRRS is endemic in many if not all the pig-producing countries

PRRS Porcine reproductive and respiratory syndrome virus (Lelystad virus). There is abortion late in gestation with respiratory tract illness in live piglets (interstitial pneumonia).

Virus

Antigenicity

  • Isolates vary in virulence
  • Some are subclinical

Hosts

  • Pigs: aka Blue Ear or Lelystad virus

Transmission and 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)

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

Diagnosis

Clinical Signs

    • Thumping respiration
    • Abortions
    • Flushed skin
    • Eyelid oedema
    • Weak or dying piglets

===Laboratory Tests+

  • 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

Prognosis

Links

References