Ovine pulmonary adenocarcinoma Ovine pulmonary adenocarcinoma Ovine pulmonary adenocarcinoma (OPA), also known as ovine pulmonary adenomatosis, or jaagsiekte, is a chronic and contagious disease of the lungs of sheep and goats. OPA is caused by a retrovirus called jaagsiekte sheep retrovirus (JSRV). The disease has a long incubation period, and therefore signs usually occur in adult animals (over 2 years of age). Clinical signs resemble a non-specific progressive pneumonia, including poor body condition and, particularly after exercise, respiratory difficulty. Unless a concurrent lung infection is present, affected sheep continue to eat. The only sign specific to OPA is a watery nasal discharge, consisting
Ovine rinderpest gene. Lineages I and II are found mainly in West Africa. Lineage III is generally found in East Africa. Lineage IV was long known as the Asian lineage, but has now spread to the African continent and become the most prevalent lineage of all. This virus appears to have evolved at the start of the 20th century in Nigeria. The extant genotypes subsequently appeared in West Africa (lineages I and II), East Africa and Arabia (lineage III), and Pakistan–India (lineage IV). The first description of the disease was published in 1942 and relates to an outbreak in Côte d’Ivoire, West