Fleas of black rats (Rattus rattus) as reservoir host ofBartonellaspp. in Chile

Abstract

BackgroundRattus 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.MethodsIn 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.ResultsOverall, 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.