The Results of Detecting Genetic Markers of Infectious Disease Pathogens Transmitted by Ixodidae Ticks in Certain Regions of the Republic of the Congo

This study was conducted in order to identify genetic markers of pathogens (RNA, 16S rRNA or DNA) of natural-focal infectious diseases of bacterial, viral and rickettsial origin in suspensions of Ixodidae ticks collected in certain regions of the Republic of the Congo. Materials and methods. The presence of markers of Q fever, rickettsiosis, anaplasmosis, ehrlichiosis, tularemia, Crimean hemorrhagic fever, tick-borne encephalitis agents was determined applying polymerase chain reaction using Russian-made diagnostic drugs. A total of 509 combined samples of ectoparasites of 5 species collected in the prefectures of Pool, Cuvette and the vicinity of Brazzaville in 2025 were studied. Results and discussion. As a result of the work, RNA of Crimean-Congo hemorrhagic fever virus (0.9 % of all samples studied), cDNA of Borrelia burgdorferi s.l. (3.9 %), DNA of Coxiella burnetii (1.8 %) and rickettsia of the tick-borne spotted fever group (45.2 %) were detected in the material from ticks. Positive results were recorded in 264 out of 509 samples (51.9 %). No genetic markers of tick-borne encephalitis, ehrlichiosis, anaplasmosis and tularemia agents were found. Some samples in which markers of the Crimean-Congo hemorrhagic fever virus, Rickettsia spp., and Coxiella burnetii in high concentrations had been identified were subjected to genetic analysis using high-throughput sequencing via nanopores on the MinIon platform (Oxford Nanopore Technologies, Great Britain); their taxonomic appurtenance to the stated systematic groups was confirmed. Based on the genetic analysis of the S segment sequences of Crimean-Congo hemorrhagic fever virus isolates, their belonging to the Africa-1 genotype with a degree of homology ranging from 98.8 % to 100 % was demonstrated. The data obtained evidences the need to continue studying the prevalence of naturalfocal infectious diseases transmitted by ticks in the Republic of the Congo and implement systematic epizootiological monitoring.

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