B157 OVINE PULMONARY ADENOMATOSIS

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B157 OVINE PULMONARY ADENOMATOSIS

Nature of the disease
Ovine Pulmonary Adenomatosis (OPA), also known as jaagsiekte and sheep pulmonary adenomatosis (SPA), is chronic disease of sheep due to a retrovirus. The virus causes respiratory problems and the issue is always fatal. 
Classification
OIE, List B disease
Susceptible species
Sheep, rarely goats
Distribution
The disease is not widely spread, it is reported by some countries in Europe, America, Africa and Asia. It has never been identified in the Pacific Region.
Clinical signs 
The period of incubation exceeds months and the clinical signs only appear when the tumours are sufficiently developed. Usually it affects sheep of 3-4 years old and signs include:
  • Increased respiratory rate (tachypnea)
  • Lost of weight despite normal appetite,
  • Wet cough,
  • Eyes and noise discharge,
  • Death after a few months, usually associated with secondary pasteurellosis.
Post-mortem findings 
Lungs may appear firm, grey and flat. They sink in water. Bronchi are full with abundant white and frothy fluid.
Differential diagnosis 
  • Maedi-Visna
  • Parasitic respiratory diseases
  • Other chronic respiratory diseases
Specimens required for diagnosis 
There is no immunological test available. The diagnosis can only be done by histological examination of lungs.
Transmission   
The virus is shed in lung secretions and is transmitted by aerosols. 
Risk of introduction   
The disease could only be introduced by importation of infected animals.
Control / vaccines  
There is no test, no treatment and no vaccine. 
References
  • Office International des Epizooties, 2002
  • Office Vétérinaire Fédéral Suisse
  • Pulmonary Adenomatosis, In Merck Veterinary Manual, National Publishing Inc. Eight ed, 1998, Philadelphia, p 1112-1113