Respiratory Viral Infections

()Map CARDIORESPIRATORY SYSTEM (Map) RESPIRATORY SYSTEM INFLAMMATION

In general

• Some viruses are thought to induce modifications of the pulmonary defences by:
  • Damaging the upper respiratory tract, thereby facilitating bacterial attachment and colonisation, with reduced mucociliary clearance
  • Decreasing surfactant levels by destroying Type 2 pneumonocytes
  • Impairing the phagocytic ability of alveolar macrophages

In Dogs

Canine Distemper Virus

Canine Parainfluenza - 2

Infectious canine tracheitis

Canine Adenovirus 1

Canine Adenovirus 2

Canine Herpesvirus 1

Canine Respiratory Coronavirus

In Horses

Equine respiratory viruses Concept Map (Courtesy of B. Stanikova)

In Sheep

Parainfluenza -3

• As in cattle

In Goats

Caprine Arthrirtis Encephalitis Virus

In Pigs

Porcine Cytomegalovirus

Porcine reproductive and respiratory syndrome

• 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

Postweaning multisystemic wasting syndrome (PMWS)

• Caused by a porcine circovirus alone or in combination with porcine parvovirus
• May cause mild interstitial pneumonia, failure of lungs to collpse on opening the thoracic cavity
• Microscopically: thickening of alveolar wall due to type 2 pneumocyte hyperplasia