Clinical and morphological manifestation of spontaneous Coxiella burnetii infection in sheep

Rashid Sitdikov,Irina Tyaglova,Orazali Mullakaev

doi:10.1051/bioconf/20202700092

Abstract

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 °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.

Highlights

It has been 85 years since the outbreak of fever of unknown nature among workers in the massacre in Brisbane (Australia)
We studied sheep killed in a failed farm due to incidence of Q fever
In animals infected with spontaneous Q fever, body temperature increased to 40.8–42 °C

Summary

Introduction

It has been 85 years since the outbreak of fever of unknown nature among workers in the massacre in Brisbane (Australia). E.Kh. Derrick’s report was a classic study that showed the origin of the name of Q infection, where Q means question. Most of its clinical symptoms were described in his report [1–3]. Some symptoms of Q fever are similar to those of typhoid and typhus fever. Its course can be similar to that of nervous malignances, brucellosis, influenza, and other diseases. Scientists Derrick and Burnet described this pathogen as Ricketsia burnetii, but unlike other rickettsia, it differed in intracellular reproduction, size, polymorphism and sensitivity to antibiotics [9]

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