High prevalence of Rickettsia felis in fleas from pets in central Argentina

In recent decades, there has been a significant increase in the emergence of infectious diseases, many of which are transmitted by ectoparasites such as fleas and ticks. In the Southern Hemisphere, transmission by these vectors is primarily associated with bacteria of the genus Rickettsia. Although the presence of Rickettsia spp. in Argentina has been previously reported, this study investigates the presence and identity of these pathogens in fleas and ticks collected from pets (Felis catus and Canis lupus familiaris) in the central region of Argentina. A total of 144 ectoparasite pools were analyzed, including 59 flea pools and 85 tick pools. Only Ctenocephalides felis felis and Rhipicephalus sanguineus sensu lato were identified. All tick pools tested negative for Rickettsia spp. However, 35.6% of C. f. felis pools (21/59) tested positive for Rickettsia sp. and sequence analysis of the ompA and ompB genes identified Rickettsia felis. Of these 21 positive pools, 10 were from dogs and 11 from cats. The minimum infection rate was 13.2%. Sequence analysis of PCR products showed 100% identity with R. felis sequences published in GenBank. Phylogenetic analysis of the ompB gene confirmed 100% identity with known R. felis sequences. Our findings confirm the presence of R. felis in fleas from pets in central Argentina. Despite the absence of reported human cases, enhanced surveillance is essential to assess the public health risk and understand the transmission dynamics of this pathogen in urban and peri-urban environments. These findings contribute to expanding the known geographic distribution of bacteria of the genus Rickettsia and support the role of C. f. felis as a potential vector and reservoir of this pathogen.