Distribution and species diversity of rickettsiae in ticks collected in Georgia

Abstract

Introduction: Rickettsial diseases, caused by obligate intracellular Gram-negative bacteria of the genus Rickettsia, are a significant public health concern due to their potential for severe morbidity and mortality. This study aimed to determine the prevalence and species distribution of Rickettsia spp. in tick populations from various regions of Georgia, providing critical updates to epidemiological data and informing public health strategies. Methods: From 2020 to 2022, 699 pooled tick samples were collected from the Kakheti, Shida Kartli, Samegrelo, and Mtskheta-Mtianeti regions. The samples were homogenised, stored at -80°C, and processed using Qiagen and MagMAX™ CORE Nucleic Acid Purification Kits for DNA extraction. Quantitative PCR (qPCR) targeting the genus-specific 17-kD gene was employed to screen for Rickettsia. Positive samples underwent further analysis with species-specific qPCR assays to identify R. raoultii, R. slovaca, R. aeschlimannii, and R. monacensis. Results: Among the 699 samples, 160 tested positive for Rickettsia DNA. Two samples were excluded from species-specific analysis due to weak positivity. Detected species included R. raoultii (3.2%), R. slovaca (11.4%), R. aeschlimannii (39.2%), and R. monacensis (10.8%). Co-infection with multiple species was observed in 10.01% of positive samples, with 39 samples not containing any of the targeted species. Conclusion: The study highlights the diverse presence of rickettsial pathogens in Georgian ticks and confirms the ongoing prevalence of R. monacensis. These findings underscore the urgent need for enhanced surveillance and rapid response strategies to mitigate the public health risks associated with rickettsial diseases. Strengthening monitoring and control measures will be crucial in addressing these health threats effectively.