Bluetongue (BT) is a disease caused by bluetongue virus (BTV) and transmitted by vectors of the genus Culicoides. Serological studies have demonstrated the widespread presence of the virus in Brazil, however, clinical information of BT in South America are limited. This article describes clinical and pathological changes observed in sheep naturally infected by BTV in southern Brazil. In two outbreaks on different farms, 15 sheep showed clinical signs such as severe hyperthermia, apathy, swelling of the face and submandibular area, difficulty in swallowing with regurgitation, greenish mucopurulent nasal secretion, severe weight loss, and erosions in the oral mucosa. Necropsy findings in six sheep included subcutaneous edema of the face and ventral region of the chest, greenish nasal discharge, and dilated esophagus filled with abundant food contents, collapsed lungs with areas of anteroventral consolidation, and trachea and bronchi filled by foamy material mixed with food. In the heart and base of the pulmonary artery there were foci of hemorrhage. Histologically, the main changes were in cardiac and skeletal muscles and consisted of biphasic lesions characterized by hyaline and floccular degeneration/necrosis of myofibers associated with micro-mineralization and mononuclear cell infiltration. Pneumonia associated with the presence of organic matter and bacteria in the lumen of the bronchi was also observed. The diagnosis of BT was confirmed by detection of the viral genome by duplex RT-PCR in blood of affected animals, followed by the identification of BTV, serotype 12 by nucleotide sequencing.
Diseases of sheep; viral diseases; bluetongue virus; Brazil
