Histopathological and Immunohistochemical Studies on Bovine Ephemeral Fever in Cattle

Bovine ephemeral fever (BEF) is an arthropod-borne viral disease of cattle caused by a single stranded RNA virus that belongs to the rhabdovirus group. The outbreak was diagnosed as BEF on the bases of clinical signs and pathological lesions. In the present study, out of two hundred and fifty cows, fourteen cows are died from BEF by mortality ratio 5.6%. The diseased cows showed viraemia, inappetance, depression, salivation, lacrimation, nasal discharge, lameness, and recumbency followed by death. Formalin-fixed paraffin-embedded samples from naturally infected cows with BEFV were grossly and microscopically evaluated and tested using immunohistochemistry. The main gross findings include grayish-white streaks in the skeletal muscles, congestion and mottling of the lung surface with darkness of the lobar septa, congestion of the tracheal mucosae with the presence of mucous exudate in their lumen. The liver and kidneys were congested with edematous and enlarged lymph nodes. The microscopical examination revealed various pathological changes in different organs. Diffuse hemorrhage and pulmonary emphysema with alveolar atelectasis and catarrhal bronchiolitis were observed in the lung. The skeletal muscle showed severe hyaline degeneration and myomalacia with inter-muscular hemorrhage. Edema with marked lymphoid depletion was observed in the pre-scapular and pre-femoral lymph nodes. Necrotic changes were noticed in the renal and intestinal tissues. Diagnosis was confirmed by detecting viral antigen in the spleen, lung, muscle, kidney, heart and lymph nodes with most of the antigen appearing within macrophages and pericytes using immunohistochemistry.