Medycyna Wet. 66 (7), 459-463, 2010
Niedbalski W., Kęsy A.
Pathology and pathogenesis of Bluetongue
The article reviews the clinical symptoms and pathogenesis of Bluetongue virus (BTV) infection of domestic and wild ruminants. The clinical signs of BTV infection occur principally in sheep but typical BT signs have also been observed in cattle infected with BTV serotype 8 in North-Western Europe. BTV infection can display a variety of clinical manifestations, ranging from subclinical or mild, to acute or even fatal infections. The lesions of BT differ not only among the animal species but also within breeds of the same species. In sheep the febrile period (41-42C) lasts about one week. Nasal discharge, salivation, hyperemia, hemorrhages of the oral and nasal mucosa are observed 24-48 hrs after onset of fever. After the next few days edema of lips, tongue, face and ears is developed. At the end of febrile period, when mouth lesions begin to heal, coronitis may occur. The pathogenesis of BTV infection is similar in all species of ruminants. After cutaneous infection of BTV, by inoculation or through the bite of a BTV-infected Culicoides vector, the virus travels along the blood vessels to the regional lymph node, the place of the first replication of BTV. The virus is then disseminated to a variety of tissues throughout the body (particularly lungs and spleen) where replication occurs principally in mononuclear phagocytic and endothelial cells, lymphocytes and other cell types. BTV replicates in endothelial cells, causing cell injury and necrosis and leading to vascular thrombosis, tissue infarction, and, consequently, to a dysfunction of organs.
Keywords: bluetongue, ruminants, clinical signs, pathogenesis