Abstract
BackgroundRattus rattus is 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 genus Bartonella, which can cause diseases in humans and animals. In Chile, no data are available identifying fleas from synanthropic rodents as Bartonella vectors. The aim of this study was to investigate the prevalence of Bartonella spp. in the fleas of R. rattus in areas with different climate conditions and featuring different human population densities.MethodsIn all, 174 fleas collected from 261 R. rattus captured 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. Bartonella spp. presence was determined through polymerase chain reaction, using gltA and rpoB genes, which were concatenated to perform a similarity analysis with BLAST and phylogenetic analysis.ResultsOverall, 15 fleas species were identified; Bartonella gltA and rpoB fragments 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 for Bartonella DNA. Leptopsylla segnis was the most commonly collected flea species (n = 55), and it also presented a high prevalence of Bartonella DNA (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 of Bartonella DNA. The presence of Bartonella DNA 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% gltA and 31.8% rpoB), followed by cities (14.8% gltA and 11.1% rpoB) and wild areas (7.4% gltA and 14.8% rpoB). The BLAST analysis showed a high similitude (>96%) with four uncharacterized Bartonella genotypes and with two species with zoonotic potential: B. mastomydis and B. tribocorum. The phylogenetic analysis showed a close relationship with B. elizabethae and B. tribocorum. This is the first study to provide evidence of the presence of Bartonella in fleas of R. rattus in Chile, indicating that the villages and arid zone correspond to areas with higher infection risk.
Highlights
Bartonella spp. are vector-borne bacteria that have been identified in a wide range of mammals (Breitschwerdt, 2017)
Due to the close contact that black rats maintain with humans and wild species; the high number of flea species described for rats in Chile (12 species; Beaucournu, Moreno & González-Acuña, 2014), and how the fleas that parasitize them can act as potential Bartonella vectors; as well as the scarce knowledge that exists about Bartonella in Chile associated with human synanthropic rodents, we investigated the prevalence of Bartonella spp. in R. rattus fleas in areas characterized by different human population densities throughout the different hydrographic zones and seasons in Chile
We highlight the high richness of flea species detected in our study compared to other studies, which could be explained due to the wide geographical range considered in our study (20–53 lat.) and to the inclusion of wild areas, in contrast to other studies that only include rural areas or cities. This is the first report on Bartonella DNA among a large number of flea species in rodents that explored a gradient of urbanization across a wide geographic distribution in Chile
Summary
Bartonella spp. are vector-borne bacteria that have been identified in a wide range of mammals (Breitschwerdt, 2017). Reports of human transmission are not frequent, some recent studies support the possibility that rodent-associated Bartonella species may be responsible for human infections, especially in areas where humans and rats are in close contact; these infections are most prevalent in homeless people and are more likely to be contracted while engaging in outdoor activities (Kosoy et al, 2008, 2010; Ying et al, 2012). Rattus rattus is 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 genus Bartonella, which can cause diseases in humans and animals.
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