Prevalence of causative agents of transmissive tick-borned ricketsious in the Crimean peninsula.

The paper presents the results of a study of the prevalence of Ixodid ticks - potential carriers of tick-borne rickettsiosis pathogens. Ectoparasites were collected in various natural and climatic zones of the Crimean Peninsula within the year 2016-2018. As a result of screening with the help of real-time PCR analysis (PCR-RT), a genetic marker (a section of the gltA gene) of the rickettsia group of tick-borne spotted fever was detected in ticks. The most common DNA marker of rickettsia was found in ticks in the eastern regions of the steppe zone - 50,6 %, in the north-western part of the steppe zone this value was 12,0 %. The least amount of rickettsia target DNA was detected in ticks collected in the mountain forest and south bank zones - 4,5 %. As a result of sequencing of positive DNA samples from fragments of the gltA, ompA, ompB, and sca4 genes, the species composition of rickettsias was established. The DNA of 8 species of rickettsia was identified: Circulation of three R. conorii, R. massiliae, R. sibirica subsp. mongolotimonae, R. slovaca, R. aeschlimannii, R. monacensis, R. helvetica, R. raoultii. R. massiliae, R. slovaca, and R. helvetica were established in the Crimean Peninsula for the first time. The peculiarities of the geographical distribution of the identified rickettsia species were determined, which was due to the spread of mites-carriers of pathogens. The revealed diversity of rickettsia species and their vectors, due to the isolation of the areas of the main feeding animals and the established routes of migratory birds, suggests the circulation of other rickettsia species on the territory of the Crimean Peninsula. The obtained results suggest that the diseases of tick-borne rickettsiosis in the Crimean Peninsula can be caused not only by R. conorii, as previously thought, but also by other types of rickettsii.

The role of Rhipicephalus sanguineus ticks parasitizing dogs in the spread of tick-borne rickettsial pathogens in the city of Sevastopol.

The occurrence of Mediterranean fever with periods of increase and decrease has been recorded in the Crimean peninsula. The city of Sevastopol and its vicinity are known endemic areas for this disease. Some of the most active agents in the spread of this rickettsiosis are feral and abandoned dogs. The aim of this study was to test ticks parasitizing dogs in Sevastopol for the presence of Rickettsia using molecular methods. The testing of ticks was carried out using real-time PCR and the 'Real Best DNA Rickettsia species' kit (AO 'Vector-Best') followed by sequence identification of the rickettsial DNA detected. The DNA marker for Rickettsia species (a conservative area of citrate synthase gene, gltA) was detected in 16 of 84 (19.1%) samples of Rhipicephalus sanguineus ticks tested. Larger fragments of gltA, ompA and sca4 were amplified and sequenced for 10 of 16 PCR-positive samples. Rickettsia DNA amplified from eight of the samples matched the sequence of Rickettsia conorii conorii Malish, the causative agent of Mediterranean fever. The sequences of Rickettsia DNA from two other ticks had the closest match to homologous fragments of Rickettsia massiliae, a pathogenic spotted fever rickettsia that was identified in the Crimean Peninsula for the first time as part of this study. The detection of two pathogenic species of Rickettsia in the studied ticks suggests the potential for two rickettsial diseases in the region and warrants further epidemiological and clinical studies.