BartonellaSpecies Identified in Rodent and Feline Hosts from Island and Mainland Western Australia

Dermacentor (Indocentor) auratus Supino 1897: Potential geographic range, and medical and veterinary significance

Dermacentor (Indocentor) auratus Supino, 1897 occurs in many regions of Southeast Asia and South Asia. In many regions of Southeast Asia and South Asia, targeted tick sampling and subsequent screening of collected D. auratus ticks have detected pathogenic bacteria and viruses in D. auratus. These disease-causing pathogens that have been detected in D. auratus include Anaplasma, Bartonella, Borrelia, Rickettsia (including spotted fever group rickettsiae), African swine fever virus, Lanjan virus, and Kyasanur forest disease virus. Although D. auratus predominantly infests wild pigs, this tick is also an occasional parasite of humans and other animals. Indeed, some 91 % of human otoacariasis cases in Sri Lanka were due to infestation by D. auratus. With the propensity of this tick to feed on multiple species of hosts, including humans, and the detection of pathogenic bacteria and viruses from this tick, D. auratus is a tick of medical, veterinary, and indeed zoonotic concern. The geographic range of this tick, however, is not well known. Therefore, in the present paper, we used the species distribution model, BIOCLIM, to project the potential geographic range of D. auratus, which may aid pathogen and tick-vector surveillance. We showed that the potential geographic range of D. auratus is far wider than the current geographic distribution of this tick, and that regions in Africa, and in North and South America seem to have suitable climates for D. auratus. Interestingly, in Southeast Asia, Borneo and Philippines also have suitable climates for D. auratus, but D. auratus has not been found in these regions yet despite the apparent close proximity of these regions to Mainland Southeast Asia, where D. auratus occurs. We thus hypothesize that the geographic distribution of D. auratus is largely dependent on the movement of wild pigs and whether or not these wild pigs are able to overcome dispersal barriers. We also review the potential pathogens and the diseases that may be associated with D. auratus and provide an updated host index for this tick.

Epidemiology and Genetic Diversity of Bartonella in Rodents in Urban Areas of Guangzhou, Southern China

Bartonella spp. are gram-negative bacteria that can infect a wide spectrum of mammals. Rodents are considered to be the natural reservoir of many Bartonella species that are transmitted by various blood-sucking arthropods. The close contact between rodents and humans in urban areas increased the chance of transmitting rodent-borne Bartonella to humans. Investigation of the epidemiological characteristics of Bartonella infection in rodents is of great significance for the prevention and control of human Bartonellosis. In this study, rodents were captured to monitor the prevalence of Bartonella in urban areas of Guangzhou city. Six official or candidate species of Bartonella, including two confirmed zoonotic species, were detected with an overall prevalence of 6.4% in rodents captured herein. In addition, Rattus norvegicus was the predominant host species for Bartonella infection, and B. queenslandensis was the dominant species circulating in rodents in these areas. These results provide insights into the prevalence and genetic diversity of Bartonella species circulating in rodents in the urban areas of Guangzhou, and also urged the surveillance of rodent-associated Bartonella species in these areas.

Emerging rodent-associated Bartonella: a threat for human health?

Background

Species of the genus Bartonella are facultative intracellular alphaproteobacteria with zoonotic potential. Bartonella infections in humans range from mild with unspecific symptoms to life threatening, and can be transmitted via arthropod vectors or through direct contact with infected hosts, although the latter mode of transmission is rare. Among the small mammals that harbour Bartonella spp., rodents are the most speciose group and harbour the highest diversity of these parasites. Human–rodent interactions are not unlikely as many rodent species live in proximity to humans. However, a surprisingly low number of clinical cases of bartonellosis related to rodent-associated Bartonella spp. have thus far been recorded in humans.

Methods

The main purpose of this review is to determine explanatory factors for this unexpected finding, by taking a closer look at published clinical cases of bartonellosis connected with rodent-associated Bartonella species, some of which have been newly described in recent years. Thus, another focus of this review are these recently proposed species.

Conclusions

Worldwide, only 24 cases of bartonellosis caused by rodent-associated bartonellae have been reported in humans. Possible reasons for this low number of cases in comparison to the high prevalences of Bartonella in small mammal species are (i) a lack of awareness amongst physicians of Bartonella infections in humans in general, and especially those caused by rodent-associated bartonellae; and (ii) a frequent lack of the sophisticated equipment required for the confirmation of Bartonella infections in laboratories that undertake routine diagnostic testing. As regards recently described Bartonella spp., there are presently 14 rodent-associated Candidatus taxa. In contrast to species which have been taxonomically classified, there is no official process for the review of proposed Candidatus species and their names before they are published. This had led to the use of malformed names that are not based on the International Code of Nomenclature of Prokaryotes. Researchers are thus encouraged to propose Candidatus names to the International Committee on Systematics of Prokaryotes for approval before publishing them, and only to propose new species of Bartonella when the relevant datasets allow them to be clearly differentiated from known species and subspecies.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-022-05162-5.

Molecular Detection of Bartonella Species in Rodents Residing in Urban and Suburban Areas of Central Thailand

Bartonella spp. are Gram-negative zoonotic bacteria transmitted to humans via various blood-sucking arthropods. Rodents have been identified as reservoir hosts of several zoonotic pathogens, including Bartonella spp. In Thailand, studies of Bartonella spp. in rodents from urban areas are limited; thus, a study in this area is necessary. The objectives of this study were to detect Bartonella spp. in rodents in Thailand and to compare the species’ distribution across different areas. In total, 70 blood samples from rodents in urban and suburban areas were tested for Bartonella spp. using a conventional polymerase chain reaction that targeted the citrate synthase (gltA) gene. All Bartonella-positive sequences were analyzed using polymorphism in order to build a phylogenetic tree. Approximately 38% of the rodents studied contained Bartonella DNA. Both Rattus exulans (Pacific rat) and R. tanezumi (Asian house rat) contained Bartonella spp. Four species of Bartonella were detected in blood samples: B. tribocorum, B. phoceensis, B. grahamii, and B. rattimassiliensis. In addition, eight Pacific rats contained the B. kosoyi–B. tribocorum complex. Bartonella phoceensis and B. tribocorum–B. kosoyi complexes were found in a specific habitat (p < 0.05). Interestingly, only seven haplotypes were identified in the sequences analyzed, and only haplotype A was found in both rodent species. Finally, a monitoring program for zoonotic Bartonella infection, especially the B. kosoyi–B. tribocorum complex, B. phoceensis, B. grahamii, and B. rattimassiliensis should be established, especially in high-risk areas.

Molecular detection of Bartonella in ixodid ticks collected from yaks and plateau pikas (Ochotona curzoniae) in Shiqu County, China

Background

Bartonella bacteria have been associated with an increasingly wide range of human and animal diseases. These emerging pathogens have been identified as being globally dispersed. Ticks and small rodents are known hosts of Bartonella and play a significant role in the preservation and circulation of Bartonella in nature. This study investigated the occurrence of hoist spp. in ticks (Acari: Ixodidae) and plateau pikas (Ochotona curzoniae) in Shiqu County, which is located on the eastern Qinghai-Tibetan Plateau in China. Shiqu County is spread over approximately 26,000 km², with an average altitude of above 4200 m and a vast area of pastureland.

Results

A total of 818 ticks (Dermacentor everestianus, 79.0%, 646/818; Haemaphysalis qinghaiensis, 21.0%, 172/818) were collected from yaks in 4 villages of Shiqu County. Only Bartonella melophagi was detected in tick samples, with a total prevalence of 30.1% (246/818). The infection rates of B. melophagi in ticks from Arizha, Maga, Derongma, and Changxgma were 4.8, 76.8, 12.5, and 18.0%, respectively. The infection rate of B. melophagi in Maga was higher (p < 0.01) than those in other villages. Regarding plateau pikas, the total infection rate of Bartonella spp. was 21.7% (62/286), with 16.7% (12/72), 30.9% (25/81), 13.8% (9/65), and 23.5% (16/68) in Arizha, Maga, Derongma, and Changxgma, respectively. Finally, B. queenslandensis and B. grahamii were detected in plateau pika. No significant difference was observed (p > 0.05) in the infection rates between these study sites.

Conclusion

To date, only D. everestianus and H. qinghaiensis were found in Shiqu County with high infection of Bartonella spp. in the ticks and plateau pika. The threats of Bartonella species to public health should be closely monitored.

Bacterial community profiling highlights complex diversity and novel organisms in wildlife ticks

Ticks Acari:Ixodida transmit a greater variety of pathogens than any other blood-feeding group of arthropods. While numerous microbes have been identified inhabiting Australian Ixodidae, some of which are related to globally important tick-borne pathogens, little is known about the bacterial communities within ticks collected from Australian wildlife. In this study, 1,019 ticks were identified on 221 hosts spanning 27 wildlife species. Next-generation sequencing was used to amplify the V1-2 hypervariable region of the bacterial 16S rRNA gene from 238 ticks; Amblyomma triguttatum (n = 6), Bothriocroton auruginans (n = 11), Bothriocroton concolor (n = 20), Haemaphysalis bancrofti (n = 10), Haemaphysalis bremneri (n = 4), Haemaphysalis humerosa (n = 13), Haemaphysalis longicornis (n = 4), Ixodes antechini (n = 29), Ixodes australiensis (n = 26), Ixodes fecialis (n = 13), Ixodes holocyclus (n = 37), Ixodes myrmecobii (n = 1), Ixodes ornithorhynchi (n = 10), Ixodes tasmani (n = 51) and Ixodes trichosuri (n = 3). After bioinformatic analyses, over 14 million assigned bacterial sequences revealed the presence of recently described bacteria 'Candidatus Borrelia tachyglossi', 'Candidatus Neoehrlichia australis', 'Candidatus Neoehrlichia arcana' and 'Candidatus Ehrlichia ornithorhynchi'. Furthermore, three novel Anaplasmataceae species were identified in the present study including; a Neoehrlichia sp. in I. australiensis and I. fecialis collected from quenda (Isoodon fusciventer) (Western Australia), an Anaplasma sp. from one B. concolor from echidna (Tachyglossus aculeatus) (New South Wales), and an Ehrlichia sp. from a single I. fecialis parasitising a quenda (WA). This study highlights the diversity of bacterial genera harboured within wildlife ticks, which may prove to be of medical and/or veterinary importance in the future.

Bartonella infections in cats and dogs including zoonotic aspects

Bartonellosis is a vector-borne zoonotic disease with worldwide distribution that can infect humans and a large number of mammals including small companion animals (cats and dogs). In recent years, an increasing number of studies from around the world have reported Bartonella infections, although publications have predominantly focused on the North American perspective. Currently, clinico-pathological data from Europe are more limited, suggesting that bartonellosis may be an infrequent or underdiagnosed infectious disease in cats and dogs. Research is needed to confirm or exclude Bartonella infection as a cause of a spectrum of feline and canine diseases. Bartonella spp. can cause acute or chronic infections in cats, dogs and humans. On a comparative medical basis, different clinical manifestations, such as periods of intermittent fever, granulomatous inflammation involving the heart, liver, lymph nodes and other tissues, endocarditis, bacillary angiomatosis, peliosis hepatis, uveitis and vasoproliferative tumors have been reported in cats, dogs and humans. The purpose of this review is to provide an update and European perspective on Bartonella infections in cats and dogs, including clinical, diagnostic, epidemiological, pathological, treatment and zoonotic aspects.