Clinical and morphological manifestation of spontaneous Coxiella burnetii infection in sheep

The study that simultaneously employed negative staining and ultra-thin sectioning to investigate the causative agent of Q fever in phase I showed that the epizootic strain exhibited morphological characters typical of C. burnetii. Investigation of the ultra-thin structure of sections and whole racketetia cells of the epizootic strain revealed clearly expressed structural basis of the elements of their arrangement and partial similarity of the strain to the reference strains. In animals infected with spontaneous Q fever, the clinical course of the disease was characterized as severe with signs of intermittent fever up to 42 degrees C, symptoms of fatigue, decreased food excitability, inactivity, catarrhal rhinitis and conjunctivitis, and cyanosis of mucous membranes. Specific, nonspecific and immunopathological processes developed in organs and tissues: specific changes were characterized by formation of epithelioid cell granulomas with Pirogov-Langhans giant cells in the lymph nodes; nonspecific changes manifested through hyperplastic, macrophage and plasma-cell reactions in lymphoid organs; immunopathological changes were characterized by indurated and fibrotized reticular stroma of lymphoid organs, plasmorrhagia, erythrodiapedesis, mucoid and fibrinoid swelling of the blood vessel walls of the microvasculature, formation of lymphoid and histiocytic infiltrates in the lungs, myocard, liver and kidneys, and dystrophic and necrotic changes in the parenchymal elements of these organs, which cumulatively indicated a morphological manifestation of an allergic reaction of DSR type. The study aimed to investigate some issues of the pathogenesis and pathomorphology of spontaneous Q fever infection in sheep.