Ovine Pulmonary Adenomatoses (OPA) is a contagious and economically significant respiratory disease affecting primarily sheep. It is caused by a group of retroviruses called Jaagsiekte sheep retroviruses (JSRVs) and is characterized by the development of tumor-like masses within the lungs of infected animals.
The disease is primarily transmitted horizontally through inhalation of viral particles shed by infected animals or via direct contact with bodily fluids. Once inhaled, the virus initially infects the respiratory epithelial cells, causing rapid proliferation and transformation into tumor cells. These tumors, known as adenomas, progressively obstruct the airways, leading to severe respiratory distress.
Symptoms of OPA typically include chronic coughing, weight loss, and difficulty breathing. In advanced stages, affected animals may exhibit labored breathing, nasal discharge, and a general decline in overall health. The disease progresses slowly and ultimately leads to mortality as a result of respiratory failure.
Diagnosis of OPA is usually confirmed through methods such as histopathological examination of lung tissue, serological testing to detect antibodies against JSRVs, or molecular techniques like polymerase chain reaction (PCR) to identify the presence of viral genetic material.
Prevention and control of OPA rely on implementing strict biosecurity measures, such as isolating and culling infected animals, as there is currently no effective treatment or vaccine available. Early detection and immediate management of infected animals are crucial for preventing the spread of OPA within sheep flocks and minimizing the economic losses associated with the disease.
