Tick-borne rickettsioses are caused by obligate intracellular bacteria belonging to the spotted fever group of the genus Rickettsia. These infections are among the oldest known diseases transmitted by vectors. In the last three decades there has been a rapid increase in the recognition of this disease complex. This unusual expansion of information was mainly caused by the development of molecular diagnostic techniques that have facilitated the identification of new and previously recognized rickettsiae. A lot of currently known bacteria of the genus Rickettsia have been considered nonpathogenic for years, and moreover, many new species have been identified with unknown pathogenicity. The genus Rickettsia is distributed all over the world. Many Rickettsia species are present on several continents. The geographical distribution of rickettsiae is related to their vectors. New cases of rickettsioses and new locations, where the presence of these bacteria is recognized, are still being identified. The variety and rapid evolution of the distribution and density of ticks and diseases which they transmit shows us the scale of the problem. This review article presents a comparison of the current understanding of the geographic distribution of pathogenic Rickettsia species to that of the beginning of the century.

Rickettsiae are an interesting group of bacteria comprising a large number of obligate intracellular species. The circulation of these bacteria in the environment depends on the presence of vectors (blood-sucking invertebrates) and their hosts. On the basis of phylogenetic analyses in 2022, a division into five groups of Rickettsia has been proposed: I belli group, II canadensis group, III typhus group, and IV and V spotted group fever (respectively II, phylogenetically older, and I). The genus Rickettsia includes species that are both pathogenic and nonpathogenic to humans and domestic and wild animals. Some Rickettsia species are invertebrate symbionts. Currently, rickettsiae, which are transmitted mainly by ticks, are spreading worldwide. This has been promoted by climate change, environmental changes caused by humans, and the synanthropisation of plants and animals. Therefore, it is extremely important to monitor the natural and urban environments. The study of potential vectors and reservoirs of bacteria in the genus Rickettsia should be a permanent part of the analysis of the modern human environment.

Tick-borne pathogens are an important medical and veterinary issue worldwide. Environmental monitoring in relation to not only climate change but also globalization is currently essential. The present study aimed to detect tick-borne pathogens of the genera Anaplasma, Rickettsia and Francisella in Ixodes ricinus ticks collected from the natural environment, i.e., recreational areas and pastures used for livestock grazing. A total of 1619 specimens of I. ricinus were collected, including ticks of all life stages (adults, nymphs and larvae). The study was performed using the PCR technique. Diagnostic gene fragments msp2 for Anaplasma, gltA for Rickettsia and tul4 for Francisella were amplified. No Francisella spp. DNA was detected in I. ricinus. DNA of A. phagocytophilum was detected in 0.54% of ticks and Rickettsia spp. in 3.69%. Nucleotide sequence analysis revealed that only one species of Rickettsia, R. helvetica, was present in the studied tick population. The present results are a part of a large-scale analysis aimed at monitoring the level of tick infestation in Northwest Poland.

Purpose: Lyme disease is the most common tick-borne disease, caused by spirochetes of the genus Borrelia, transmitted by ticks of the Ixodes genus in Poland. The purpose of this analysis was whether the COVID-19 outbreak had a significant impact on the number of reported Lyme disease cases. Materials and Methods: The data included in the World Health Organization (WHO) and the data from the “Reports on incidence of infectious diseases, infections and poisoning in Poland” presented by the Department of Epidemiology NIZP-PZH were analyzed. Results: To the end of 2020, there were registered 12, 524 Lyme disease cases. In the same period, in 2018 and 2019 were registered, respectively, 20, 150 and 20, 614 Lyme disease cases. The overall number of Lyme disease cases in 2018 and 2019 was at a similar level. The monthly increase in the number of cases was also at a similar level. The year 2020 in January and February was characterized by the same increase in the number of cases as in previous years. The difference started to be noticeable in March and the lowered growth compared to the previous years has been maintained to this day. In December, about 8, 000 fewer cases of Lyme disease were registered than in previous years. Conclusion: The reduced number of cases of Lyme disease coincided with the beginning of the COVID-19 epidemic in Poland in March 2020. Every year, the incidence of Lyme disease in Poland is at a similar level with a similar monthly increase. The outbreak of the COVID-19 pandemic had a significant impact on the number of cases recorded, which could have catastrophic consequences for people who did not receive treatment in the right time.