Jaagsiekte

Jaagsiekte (jaag·siek·te) is a chronic and contagious disease of the lungs in sheep and goats. The word derives from Afrikaans and means "Chasing Sickness" such that animals afflicted with the disease are panting and in respiratory distress as if they are out of breath from being chased. It is also referred to as Ovine Pulmonary Carcinoma (OPC).

The disease is caused by a retrovirus called the Jaagsiekte Sheep Retrovirus (JSRV) which acutely transforms the lung epithelia. Specifically, Type-2 pneumocytes and Clara Cells are the target for JSRV transformation and tumor formation originates from these cells. The tumors exhibit the overactive secratory functions which are a hallmark of Jaagsiekte.

A common field assessment for Jaagsiekte is the "wheelbarrow test" where one lifts the hind legs of the sheep to observe lung exudate flow out the nose and mouth. This fluid contains infectious retrovirus.