Bartonella in Norway rats (Rattus norvegicus) from the urban slum environment in Brazil.

Bartonella are rodent-borne bacteria that cause varied human etiologies. Studies on synanthropic rodents are rare, causing gaps in epidemiological knowledge. We tested bloodclot samples from 79 rats from an urban slum in Salvador, Brazil through PCR targeting gltA gene. Nine samples (11.4%) were positive: six had 100% identity with Bartonella sp. isolate JF429580 and 99.5% with B. queenslandensis strain AUST/NH8; three were 100% identical to isolate JF429532 and 99.7% to B. tribocorum. This is the second report on urban rat Bartonella indicating bacterial circulation at detectable rates. Its presence in rats from vulnerable human settlements demands public health attention.

Human Exposure to Novel Bartonella Species from Contact with Fruit Bats.

Twice a year in southwestern Nigeria, during a traditional bat festival, community participants enter designated caves to capture bats, which are then consumed for food or traded. We investigated the presence of Bartonella species in Egyptian fruit bats (Rousettus aegyptiacus) and bat flies (Eucampsipoda africana) from these caves and assessed whether Bartonella infections had occurred in persons from the surrounding communities. Our results indicate that these bats and flies harbor Bartonella strains, which multilocus sequence typing indicated probably represent a novel Bartonella species, proposed as Bartonella rousetti. In serum from 8 of 204 persons, we detected antibodies to B. rousetti without cross-reactivity to other Bartonella species. This work suggests that bat-associated Bartonella strains might be capable of infecting humans.

Declines in large wildlife increase landscape-level prevalence of rodent-borne disease in Africa.

Populations of large wildlife are declining on local and global scales. The impacts of this pulse of size-selective defaunation include cascading changes to smaller animals, particularly rodents, and alteration of many ecosystem processes and services, potentially involving changes to prevalence and transmission of zoonotic disease. Understanding linkages between biodiversity loss and zoonotic disease is important for both public health and nature conservation programs, and has been a source of much recent scientific debate. In the case of rodent-borne zoonoses, there is strong conceptual support, but limited empirical evidence, for the hypothesis that defaunation, the loss of large wildlife, increases zoonotic disease risk by directly or indirectly releasing controls on rodent density. We tested this hypothesis by experimentally excluding large wildlife from a savanna ecosystem in East Africa, and examining changes in prevalence and abundance of Bartonella spp. infection in rodents and their flea vectors. We found no effect of wildlife removal on per capita prevalence of Bartonella infection in either rodents or fleas. However, because rodent and, consequently, flea abundance doubled following experimental defaunation, the density of infected hosts and infected fleas was roughly twofold higher in sites where large wildlife was absent. Thus, defaunation represents an elevated risk in Bartonella transmission to humans (bartonellosis). Our results (i) provide experimental evidence of large wildlife defaunation increasing landscape-level disease prevalence, (ii) highlight the importance of susceptible host regulation pathways and host/vector density responses in biodiversity-disease relationships, and (iii) suggest that rodent-borne disease responses to large wildlife loss may represent an important context where this relationship is largely negative.

Molecular Survey of Bartonella Species and Yersinia pestis in Rodent Fleas (Siphonaptera) From Chihuahua, Mexico.

Rodent fleas from northwestern Chihuahua, Mexico, were analyzed for the presence of Bartonella and Yersinia pestis. In total, 760 fleas belonging to 10 species were tested with multiplex polymerase chain reaction analysis targeting the gltA (338-bp) and pla genes (478-bp) of Bartonella and Y. pestis, respectively. Although none was positive for Y. pestis, 307 fleas were infected with Bartonella spp., resulting in an overall prevalence of 40.4%. A logistic regression analysis indicated that the presence of Bartonella is more likely to occur in some flea species. From a subset of Bartonella-positive fleas, phylogenetic analyses of gltA gene sequences revealed 13 genetic variants clustering in five phylogroups (I­V), two of which were matched with known pathogenic Bartonella species (Bartonella vinsonii subsp. arupensis and Bartonella washoensis) and two that were not related with any previously described species or subspecies of Bartonella. Variants in phylogroup V, which were mainly obtained from Meringis spp. fleas, were identical to those reported recently in their specific rodent hosts (Dipodomys spp.) in the same region, suggesting that kangaroo rats and their fleas harbor other Bartonella species not reported previously. Considering the Bartonella prevalence and the flea genotypes associated with known pathogenic Bartonella species, we suggest that analysis of rodent and flea communities in the region should continue for their potential implications for human health. Given that nearby locations in the United States have reported Y. pestis in wild animals and their fleas, we suggest conducting larger-scale studies to increase our knowledge of this bacterium.

Bartonella spp. in rats and zoonoses, Los Angeles, California, USA.

Bartonella spp. were detected in rats (Rattus norvegicus) trapped in downtown Los Angeles, California, USA. Of 200 rats tested, putative human pathogens, B. rochalimae and B. tribocorum were found in 37 (18.5%) and 115 (57.5%) rats, respectively. These bacteria among rodents in a densely populated urban area are a public health concern.

Bartonella vinsonii subsp. arupensis in humans, Thailand.

We identified Bartonella vinsonii subsp. arupensis in pre-enriched blood of 4 patients from Thailand. Nucleotide sequences for transfer-messenger RNA gene, citrate synthase gene, and the 16S-23S rRNA internal transcribed spacer were identical or closely related to those for the strain that has been considered pathogenic since initially isolated from a human in Wyoming, USA.

Development of a novel genus-specific real-time PCR assay for detection and differentiation of Bartonella species and genotypes.

The genus Bartonella includes numerous species with varied host associations, including several that infect humans. Development of a molecular diagnostic method capable of detecting the diverse repertoire of Bartonella species while maintaining genus specificity has been a challenge. We developed a novel real-time PCR assay targeting a 301-bp region of the ssrA gene of Bartonella and demonstrated specific amplification in over 30 Bartonella species, subspecies, and strains. Subsequent analysis of ssrA sequences was sufficient to discriminate Bartonella species and provided phylogenetic data consistent with that of gltA, a commonly used gene for differentiating Bartonella genotypes. Using this assay, we identified Bartonella DNA in 29% and 47% of blood specimens from elk in Wyoming and cattle in the Republic of Georgia, respectively. Sequence analysis of a subset of genotypes from elk specimens revealed a cluster most closely related to Bartonella capreoli, and genotypes from cattle were identified as Bartonella bovis, both Bartonella species commonly found in wild and domestic ruminants. Considering the widespread geographic distribution and infectivity potential to a variety of hosts, this assay may be an effective diagnostic method for identification of Bartonella infections in humans and have utility in Bartonella surveillance studies.

Bartonella species in dogs and their ectoparasites from Khon Kaen Province, Thailand.

In order to access the prevalence of Bartonella species in dogs, whole blood and any associated ectoparasites were collected from 164 dogs with owners in 25 villages throughout Khon Kaen Province. DNA was extracted from dog blood, 92 ticks (Rhipicephalus sanguineus) and 137 fleas (Ctenocephalides spp) and screened by PCR using intergenic spacer region and citrate synthase gene primers. B. clarridgeiae DNA was detected in blood of 3 dogs, 4 C. felis and 1 C. canis; B. rochalimae DNA was found in 1 tick; and B. vinsonii subsp vinsonii DNA was found in 2 C. felis. The findings indicate that dogs residing in northeast Thailand are exposed to diverse Bartonella species that are also potential human pathogens.

Molecular detection and identification of Bartonella species in Xenopsylla cheopis fleas (Siphonaptera: Pulicidae) collected from Rattus norvegicus rats in Los Angeles, California.

Of 200 individual Xenopsylla cheopis fleas removed from Rattus norvegicus rats trapped in downtown Los Angeles, CA, 190 (95%) were positive for the presence of Bartonella DNA. Ninety-one amplicons were sequenced: Bartonella rochalimae-like DNA was detected in 66 examined fleas, and Bartonella tribocorum-like DNA was identified in 25 fleas. The data obtained from this study demonstrate an extremely high prevalence of Bartonella DNA in rat-associated fleas.

Persistent infection or successive reinfection of deer mice with Bartonella vinsonii subsp. arupensis.

Bartonella infections are common in rodents. From 1994 to 2006, longitudinal studies of a rodent community, consisting mainly of deer mice (Peromyscus maniculatus), were conducted in southwestern Colorado to study hantaviruses. Blood samples from deer mice captured one or more times during the period 2003 to 2006 (n = 737) were selected to study bartonellae in deer mice. Bartonellae were found to be widely distributed in that population, with an overall prevalence of 82.4% (607/737 mice). No correlation was found between bartonella prevalence and deer mouse weight or sex. Persistent or successive infections with bartonellae were observed in deer mice captured repeatedly, with a prevalence of 83.9% (297/354), and the infection appeared to last for more than 1 year in some of them. Persistent infection with bartonellae may explain the high prevalence of these bacteria in deer mice at this site and, perhaps, elsewhere. Genetic analysis demonstrated that deer mouse-borne bartonella isolates at this site belong to the same species, B. vinsonii subsp. arupensis, demonstrating a specific relationship between B. vinsonii subsp. arupensis and deer mice.

Molecular detection of Bartonella species in ticks from Peru.

A total of 103 ticks, collected from canines, horses, donkeys, and snakes from Peru, were screened for the presence of Bartonella DNA by polymerase chain reaction analysis. Bartonella DNA was detected in two ticks using Bartonella 16S-23S intergenic spacer region primers and in an additional two ticks using Bartonella NADH dehydrogenase gamma subunit gene (nuoG) primers. Bartonella rochalimae Eremeeva et al., B. quintana Schmincke, and B. elizabethae Daly et al. DNA was detected in a Rhipicephalus sanguineus Latreille (Acari: Ixodidae) female tick removed from a dog and B. quintana DNA was present in a Dermacentor nitens Neumann (Acari: Ixodidae) pool of five larvae, one nymph, and one adult male tick collected from donkeys. This is the first study to report the detection of B. rochalimae, B. quintana, and B. elizabethae DNA in ticks from Peru. Further investigations must be performed to decipher the role ticks may play in the transmission of Bartonella species.

Bats are key hosts in the radiation of mammal-associated Bartonella bacteria.

Bats are notorious reservoirs of several zoonotic diseases and may be uniquely tolerant of infection among mammals. Broad sampling has revealed the importance of bats in the diversification and spread of viruses and eukaryotes to other animal hosts. Vector-borne bacteria of the genus Bartonella are prevalent and diverse in mammals globally and recent surveys have revealed numerous Bartonella lineages in bats. We assembled a sequence database of Bartonella strains, consisting of nine genetic loci from 209 previously characterized Bartonella lineages and 121 new cultured isolates from bats, and used these data to perform a comprehensive phylogenetic analysis of the Bartonella genus. This analysis included estimation of divergence dates using a molecular clock and ancestral reconstruction of host associations and geography. We estimate that Bartonella began infecting mammals 62 million years ago near the Cretaceous-Paleogene boundary. Additionally, the radiation of particular Bartonella clades correlate strongly to the timing of diversification and biogeography of mammalian hosts. Bats were inferred to be the ancestral hosts of all mammal-associated Bartonella and appear to be responsible for the early geographic expansion of the genus. We conclude that bats have had a deep influence on the evolutionary radiation of Bartonella bacteria and their spread to other mammalian orders. These results support a 'bat seeding' hypothesis that could explain similar evolutionary patterns in other mammalian parasite taxa. Application of such phylogenetic tools as we have used to other taxa may reveal the general importance of bats in the ancient diversification of mammalian parasites.

Flea Presence and Abundance Are not Predictors of Bartonella tribocorum Carriage in Norway Rats (Rattus norvegicus) from an Underserved Neighborhood of Vancouver, Canada.

Urban Norway rats (Rattus norvegicus) carry pathogenic Bartonella spp. that are transmitted among rats and from rats to people through arthropod vectors, particularly fleas. There is marked temporospatial variation in Bartonella spp. carriage among Norway rats in Vancouver, Canada, and we investigated whether this variation is associated with flea presence or abundance. Bartonella triborocum was isolated from 96/370 (35%) rats and 211 (57%) rats had fleas with an average of one flea per rat. All fleas were identified as Nosopsyllus fasciatus. There was no significant relationship between B. tribocorum carriage and flea presence or abundance, suggesting that, in contrast to other rat-associated zoonoses transmitted by fleas (e.g., Yersinia pestis) flea indices may not be informative for understanding the ecology of Bartonella spp. in rats, particularly for N. fasciatus.

Improved detection of Bartonella DNA in mammalian hosts and arthropod vectors by real-time PCR using the NADH dehydrogenase gamma subunit (nuoG).

We used a whole-genome scanning technique to identify the NADH dehydrogenase gamma subunit (nuoG) primer set that is sensitive and specific enough to detect a diverse number of Bartonella species in a wide range of environmental samples yet maintains minimal cross-reactivity to mammalian host and arthropod vector organisms.

Bartonella genotypes in fleas (insecta: siphonaptera) collected from rodents in the negev desert, Israel.

Fleas collected from rodents in the Negev Desert in southern Israel were molecularly screened for Bartonella species. A total of 1,148 fleas, collected from 122 rodents belonging to six species, were pooled in 245 pools based on flea species, sex, and rodent host species. Two Bartonella gene fragments, corresponding to RNA polymerase B (rpoB) and citrate synthase (gltA), were targeted, and 94 and 74 flea pools were found positive by PCR, respectively. The Bartonella 16S-23S internal transcribed spacer (ITS) region was also targeted, and 66 flea pools were found to be positive by PCR. Sixteen different Bartonella gltA genotypes were detected in 94 positive flea pools collected from 5 different rodent species, indicating that fleas collected from each rodent species can harbor several Bartonella genotypes. Based on gltA analysis, identified Bartonella genotypes were highly similar or identical to strains previously detected in rodent species from different parts of the world. A gltA fragment 100% similar to Bartonella henselae was detected in one flea pool. Another 2 flea pools contained gltA fragments that were closely related to B. henselae (98% similarity). The high sequence similarities to the zoonotic pathogen B. henselae warrant further investigation.

Prevalence and genetic diversity of bartonella species detected in different tissues of small mammals in Nepal.

Bartonellae were detected in a total of 152 (23.7%) of 642 tissues from 108 (48.4%) of 223 small mammals trapped in several urban areas of Nepal. Based on rpoB and gltA sequence analyses, genotypes belonging to seven known Bartonella species and five genotypes not belonging to previously known species were identified in these animals.

Rapid diversification by recombination in Bartonella grahamii from wild rodents in Asia contrasts with low levels of genomic divergence in Northern Europe and America.

Bartonella is a genus of vector-borne bacteria that infect the red blood cells of mammals, and includes several human-specific and zoonotic pathogens. Bartonella grahamii has a wide host range and is one of the most prevalent Bartonella species in wild rodents. We studied the population structure, genome content and genome plasticity of a collection of 26 B. grahamii isolates from 11 species of wild rodents in seven countries. We found strong geographic patterns, high recombination frequencies and large variations in genome size in B. grahamii compared with previously analysed cat- and human-associated Bartonella species. The extent of sequence divergence in B. grahamii populations was markedly lower in Europe and North America than in Asia, and several recombination events were predicted between the Asian strains. We discuss environmental and demographic factors that may underlie the observed differences.

Human isolates of Bartonella tamiae induce pathology in experimentally inoculated immunocompetent mice.

BACKGROUND: Bartonella tamiae, a newly described bacterial species, was isolated from the blood of three hospitalized patients in Thailand. These patients presented with headache, myalgia, anemia, and mild liver function abnormalities. Since B. tamiae was presumed to be the cause of their illness, these isolates were inoculated into immunocompetent mice to determine their relative pathogenicity in inducing manifestations of disease and pathology similar to that observed in humans. METHODS: Three groups of four Swiss Webster female mice aged 15-18 months were each inoculated with 10(6-7) colony forming units of one of three B. tamiae isolates [Th239, Th307, and Th339]. A mouse from each experimental group was sampled at 3, 4, 5 and 6 weeks post-inoculation. Two saline inoculated age-matched controls were included in the study. Samples collected at necropsy were evaluated for the presence of B. tamiae DNA, and tissues were formalin-fixed, stained with hematoxylin and eosin, and examined for histopathology. RESULTS: Following inoculation with B. tamiae, mice developed ulcerative skin lesions and subcutaneous masses on the lateral thorax, as well as axillary and inguinal lymphadenopathy. B. tamiae DNA was found in subcutaneous masses, lymph node, and liver of inoculated mice. Histopathological changes were observed in tissues of inoculated mice, and severity of lesions correlated with the isolate inoculated, with the most severe pathology induced by B. tamiae Th239. Mice inoculated with Th239 and Th339 demonstrated myocarditis, lymphadenitis with associated vascular necrosis, and granulomatous hepatitis and nephritis with associated hepatocellular and renal necrosis. Mice inoculated with Th307 developed a deep dermatitis and granulomas within the kidneys. CONCLUSIONS: The three isolates of B. tamiae evaluated in this study induce disease in immunocompetent Swiss Webster mice up to 6 weeks after inoculation. The human patients from whom these isolates were obtained had clinical presentations consistent with the multi-organ pathology observed in mice in this study. This mouse model for B. tamiae induced disease not only strengthens the causal link between this pathogen and clinical illness in humans, but provides a model to further study the pathological processes induced by these bacteria.