Ecology and epidemiology of spotted fever group Rickettsiae and new data from their study in Russia and Kazakhstan.

Rickettsiae represent a wide range of pathogenicity from classic and new pathogens to endosymbionts of eukaryotic cells. Recent studies of rickettsiae have widened the number of representatives of genus Rickettsia, especially in the spotted fever group (SFG). Rickettsiae of SFG are tick-borne microorganisms with effective transovarial and transstadial transmission. The main hosts are ticks (Dermacentor, Rhipicephalus, Haemophysalis, Ixodes, and Amlyomma). Strategy of maintenance of tick microorganisms is vector-type transfer and tropism to endothelial cells or blood cells of animals. The main epidemiological characteristics of SFG rickettsioses are different kinds of anthropogenic activity and connection of morbidity with seasonal tick activity. Two other important characteristics are quantitative and qualitative heterogeneity of its populations (different genotypes of Rickettsia in the same territory and species of ticks, for example) and coexistence of different tick microorganisms (rickettsiae, borreliae, ehrlichiae, tick-borne encephalitis complex viruses, etc.). The role of new rickettsial genotypes in infectious diseases is poorly understood. Simultaneous study of ticks after bites, blood and skin biopsies of patients may be used for detection of spectrum of tick-borne pathogens in mixed natural foci. Interference between rickettsiae with different virulence may affect its populations and levels of morbidity.

[Genotyping of spotted tick fever rickettsiae, detected in Russia and Kazakhstan]. / Genotipirovanie rikketsii gruppy kleshchevoi piatnistoi likhoradki, vyiavlennykh v Rossii i Kazakhstane.

R. slovaca was first detected in the ticks D. marginatus gathered in the Stavropol Territory and the Voronezh Region (European Russia). The recently discovered rickettsial genotype DnS14 was first found in the ticks D. silvarum from Buryatia and D. niveus from the Karaganda Region (Central Kazakhstan). The rickettsial genotype RpA4 was most common in the ticks of the genus Dermacentor in Russia and Central Kazakhstan. An analysis of the spread of rickettsias of the STF group shows their close ecological relation to definite types of Ixodes. The rickettsias R. slovaca and RpA4 co-exist in the ticks D. marginatus and D. reticulatus (the western part of a Dermacentor area in Eurasia) and DnS14 and R. sibirica do in D. nuttalli and D. silvarum (the eastern part of the area). D. marginatus and D. reticulatus in the areas characterized by the most specific saturation of a Dermacentor area (the south of West Siberia) are carriers and reservoir of R. sibirica. The rickettsial genotype DnS28 may be now considered to be environmentally associated with one species of ticks--D. nuttalli. At least 6 genotypes of STF rickettsias--R. sibirica, R. astrahan fever (R. conorii), R. slovaca, RpA4, DnS14, DnS28--has been currently identified in Russia and Kazakhstan.

[New evidence for the detection of ehrlichia and anaplasma in ixodes ticks in Russia and Kazakhstan]. / Novye dannye o vyiavlenii érlikhii i anaplazm v iksodovykh kleshchakh v Rossii i Kazakhstane.

Polymerase chain reaction and sequence analysis were used to screen Ehrlichia and Anaplasma DNA in 900 specimens of Ixodes ticks of four genera (Dermacetor, Haemaphysalis, Ixodes, and Hyalomma) collected on 14 administrative territories of Russia and Kazakhstan. Anaplasma phagocytophilia DNA was detected and identified in Ixodes persulcatus ticks gathered in the Altai and Primorye Territories. Ehrlichia muris DNA was genotyped in the I. persulcatus ticks collected in the Tyumen, Omsk, and Novosibirsk Regions and the Altai Territory. Examining the Haemaphysalis concinna collected in the Primorye Territory revealed A. bovis DNA. The I. persulcatus ticks gathered in the Omsk Region were found to have "Ehrlichia-like "Schotti variant" DNA, Studying the ticks of the genera Dermatocentor and Hyalomma gathered in Russia and Kazakhstan failed to detect the representatives of the genera Anaplasma and Ehrlichia. The detection of A. phagocytophilia DNA in the I. persulcatus ticks in the Altai and Primorye territories and the serological verification of cases of human granulocytic anaplasmosis among patients with tick-borne infections in these territories lead to the conclusion that there are natural loci of this disease in West Siberia and the Far East of Russia.