[The biological properties of Rickettsia burnetii isolated in the northwestern Ukrainian SSR].

Biological properties of two strains of the Burnet rickettsia isolated in the natural foci of the Q fever in the northwest of the Ukrainian SSR are studied. Strain "Gishin" was characterized by high virulence for the laboratory animals and considerably exceeded the strain "Politsa" in the virulent properties. Antigen of phase I prepared from the strain "Politsa" was highly active in revealing the corresponding antibodies. The high-sensitive reaction of indirect immunofluorescence has shown the possibility to determine antibodies to phase I of the agent already from the 17th day after infection. Circulation of the Q fever agent with different virulent properties has indicated the necessity of purposeful diagnosis of this sickness both among the acute fever diseases and among flaccid course, subclinical and chronic ones not excluding the etiological role of the Burnet rickettsia.