Background: Rattus rattusis a widely distributed, invasive species that presents an important role in disease transmission, either directly or through vector arthropods such as fleas. These black rats can transmit a wide variety of pathogens, including bacteria of the genusBartonella, which can cause diseases in humans and animals. In Chile, no data are available identifying fleas from synanthropic rodents asBartonellavectors. The aim of this study was to investigate the prevalence ofBartonellaspp. in the fleas ofR. rattusin areas with different climate conditions and featuring different human population densities.Methods: In all, 174 fleas collected from 261R. rattuscaptured from 30 localities with different human densities (cities, villages, and wild areas) across five hydrographic zones of Chile (hyper-arid, arid, semi-arid, sub-humid, and hyper-humid) were examined.Bartonellaspp. presence was determined through polymerase chain reaction, usinggltAandrpoBgenes, which were concatenated to perform a similarity analysis with BLAST and phylogenetic analysis.Results: Overall, 15 fleas species were identified;Bartonella gltAandrpoBfragments were detected in 21.2% (37/174) and 19.5% (34/174) of fleas, respectively. A total of 10 of the 15 fleas species found were positive forBartonellaDNA.Leptopsylla segniswas the most commonly collected flea species (n= 55), and it also presented a high prevalence ofBartonellaDNA (P% = 34.5%). The highest numbers of fleas of this species were collected in villages of the arid zone. There were no seasonal differences in the prevalence ofBartonellaDNA. The presence ofBartonellaDNA in fleas was recorded in all hydrographic areas, and the arid zone presented the highest prevalence of this species. Regarding areas with different human densities, the highest prevalence was noted in the villages (34.8%gltAand 31.8%rpoB), followed by cities (14.8%gltAand 11.1%rpoB) and wild areas (7.4%gltAand 14.8%rpoB). The BLAST analysis showed a high similitude (>96%) with four uncharacterizedBartonellagenotypes and with two species with zoonotic potential:B. mastomydisandB. tribocorum. The phylogenetic analysis showed a close relationship withB. elizabethaeandB. tribocorum. This is the first study to provide evidence of the presence ofBartonellain fleas ofR. rattusin Chile, indicating that the villages and arid zone correspond to areas with higher infection risk.

Background: Rickettsial diseases are considered important in public health due to their dispersal capacity determined by the particular characteristics of their reservoirs and/or vectors. Among the latter, fleas play an important role, since the vast majority of species parasitize wild and invasive rodents, so their detection is relevant to be able to monitor potential emerging diseases. The aim of this study was to detect, characterize, and compare Rickettsia spp. from the fleas of micromammals in areas with different human population densities in Chile. Methods: The presence of Rickettsia spp. was evaluated by standard polymerase chain reaction (PCR) and sequencing in 1315 fleas collected from 1512 micromammals in 29 locations, with different human population densities in Chile. A generalized linear model (GLM) was used to identify the variables that may explain Rickettsia prevalence in fleas. Results: DNA of Rickettsia spp. was identified in 13.2% (174 of 1315) of fleas tested. Fifteen flea species were found to be Rickettsia-positive. The prevalence of Rickettsia spp. was higher in winter, semi-arid region and natural areas, and the infection levels in fleas varied between species of flea. The prevalence of Rickettsia among flea species ranged between 0–35.1%. Areas of lower human density showed the highest prevalence of Rickettsia. The phylogenetic tree showed two well-differentiated clades with Rickettsia bellii positioned as basal in one clade. The second clade was subdivided into two subclades of species related to Rickettsia of the spotted fever group. Conclusions: To our knowledge, this is the first report of the occurrence and molecular characterization of Rickettsia spp. in 15 flea species of micromammals in Chile. In this study, fleas were detected carrying Rickettsia DNA with zoonotic potential, mainly in villages and natural areas of Chile. Considering that there are differences in the prevalence of Rickettsia in fleas associated with different factors, more investigations are needed to further understand the ecology of Rickettsia in fleas and their implications for human health.