Coxiella

The causative agent of the Ku fever is a bacterium of the species Coxiella burnetii, which are included in the class Gammuproleu bacteria, the order of Legionellales, the family Coxiellaceae, the genus Coxiella. The causative agent was isolated in 1937 in Australia by F. Burnett and M. Freeman.

[1], [2], [3], [4], [5], [6], [7], [8], [9]

Coxhelial morphology

Koksiella - short gram-negative coccobacteria, 0.2x0.7 microns in size, pleomorphic. By Zdrodovsky and Romanovsky-Giemsa are painted in red.

Cultural properties of coke

Loose intracellular parasites. Cultivated in cell cultures, yolk sac chicken embryos, the body of guinea pig. In cells they reproduce in cytoplasmic vacuoles, they can reproduce in phagolysosomes.

[10], [11], [12]

Antigenic structure and pathogenicity of coxiella

Koksiella are subject to phase variations, which differ in morphology and antigen specificity. Koksiella, located in phase 1, have a structural polysaccharide in the cell membrane, are hydrophilic, have greater immunogenicity, are not absorbed by phagocytes in the absence of antibodies. Koksiella, located in phase 2, less virulent, sensitive to phagocytosis. The transition to phase 2 occurs after repeated cultivation in a chicken embryo. In infected cells, coxiella form spore-like forms that are most pathogenic to humans.

[13], [14], [15], [16]

Resistance of coxiella

Highly resistant to the environment. Resistant to the action of formalin, phenol. Resistance to high temperatures and low pH values, to drying, is associated with the ability to form endospore-like forms. Months persist in water and on microbially contaminated objects. Up to 2 years of age remain in dried feces.

Immunity

At the onset of the disease, antibodies to phase 2 appear in the blood, and at the height of the disease and in the convalescents antibodies to phase 1 are detected.

Epidemiology of fever

The reservoir in nature is large and small cattle, horses, rodents, wild birds. Maintenance of the microbe in nature is due to the circulation of the causative agent between animals and birds with the participation of multiple species of ixodid and argasic glue. The anthropoid vector does not play a role in the transmission of the pathogen to humans. In animals, the fever of Q fever can be asymptomatic, the causative agent is excreted in large quantities with urine, feces, amniotic fluid, milk. The person basically becomes infected, inhaling sprays of urine and feces of infected animals, and also using milk from infected animals, contaminated water. Infected aerosols and dust can infect the conjunctiva. Possible contamination through damaged skin in contact with infected amniotic fluid of animals. Sprays of coxiella-infected aerosols can cause an infectious process at a distance of several kilometers from the source of the infection. Therefore, Coxiella burnetii is considered as one of the agents of bioterror, is a member of group B of bioterrorism agents. The transmission of the disease from person to person is not noted.

[17], [18], [19],

Symptoms of fever

The incubation period is 18-21 days. The disease is accompanied by fever, headache, symptoms of acute respiratory disease, which occurs as atypical pneumonia. Nausea and vomiting may occur. In patients with pneumonia caused by Coxiella burnetii, liver damage is observed with the development of hepatolyenal syndrome. Sometimes the disease is accompanied by endocarditis. Mortality is not more than 1%.

Diagnosis of fever

Diagnosis of fever is carried out by the serological method of serology together with the diagnosis of other atypical pneumonia (chlamydia, legionella and mycoplasmal etiology), with the help of RSK, ELISA, indirect RIF.

[20], [21], [22], [23], [24], [25]

Treatment of fever

Treatment of fever is performed by antibiotics of tetracycline and a new series and fluoroquinolones.

Prevention of fever

Vaccination against ku-fever with the help of live vaccine from strain M-44 (PF Zdrodovsky, VA Genig) helps to prevent fever of KU. It is used for epidemiological reasons. Nonspecific prevention is reduced to sanitary-veterinary measures.