Prevalence, Isolation and Molecular Characterization of Bartonella Species in Republic of Korea

Molecular surveillance of zoonotic pathogens from wild rodents in the Republic of Korea

BACKGROUND

Rodents are recognized as major reservoirs of numerous zoonotic pathogens and are involved in the transmission and maintenance of infectious diseases. Furthermore, despite their importance, diseases transmitted by rodents have been neglected. To date, there have been limited epidemiological studies on rodents, and information regarding their involvement in infectious diseases in the Republic of Korea (ROK) is still scarce.

METHODOLOGY/PRINCIPAL FINDINGS

We investigated rodent-borne pathogens using nested PCR/RT-PCR from 156 rodents including 151 Apodemus agrarius and 5 Rattus norvegicus from 27 regions in eight provinces across the ROK between March 2019 and November 2020. Spleen, kidney, and blood samples were used to detect Anaplasma phagocytophilum, Bartonella spp., Borrelia burgdorferi sensu lato group, Coxiella burnetii, Leptospira interrogans, and severe fever with thrombocytopenia syndrome virus (SFTSV). Of the 156 rodents, 73 (46.8%) were infected with Bartonella spp., 25 (16.0%) with C. burnetii, 24 (15.4%) with L. interrogans, 21 (13.5%) with A. phagocytophilum, 9 (5.8%) with SFTSV, and 5 (3.2%) with Borrelia afzelii. Co-infections with two and three pathogens were detected in 33 (21.1%) and 11 rodents (7.1%), respectively. A. phagocytophilum was detected in all regions, showing a widespread occurrence in the ROK. The infection rates of Bartonella spp. were 83.3% for B. grahamii and 16.7% for B. taylorii.

CONCLUSIONS/SIGNIFICANCE

To the best of our knowledge, this is the first report of C. burnetii and SFTSV infections in rodents in the ROK. This study also provides the first description of various rodent-borne pathogens through an extensive epidemiological survey in the ROK. These results suggest that rodents harbor various pathogens that pose a potential threat to public health in the ROK. Our findings provide useful information on the occurrence and distribution of zoonotic pathogens disseminated among rodents and emphasize the urgent need for rapid diagnosis, prevention, and control strategies for these zoonotic diseases.

Epidemiological characteristics and genetic diversity of Bartonella species in rodents from southeastern China

Rodents are the primary hosts of Bartonella species and carry more than 22 Bartonella species. However, the information on epidemiological characteristics and genetic diversity of Bartonella species in rodents in southeastern China is limited. From 2015 to 2020, 1,137 rodents were captured. Bartonella-positive DNA was detected in 14.9% (169/1,137) of rodents by PCR for both the ssrA and gltA genes. A highest Bartonella prevalence was detected in Apodemus agrarius (33.5%) and lowest in B. indica (1.8%). The probability of Bartonella infection in summer (20.1%) was higher than in spring (14.6%; p = .011, OR = 1.756). Sequencing and phylogenetic analysis revealed that nine known Bartonella species were identified in rodents, including B. tribocorum, B. grahamii, B. rattimassiliensis, B. queenslandensis, B. elizabethae, B. phoceensis, B. coopersplainsensis, B. japonica and B. rochalimae. In our study, Bartonella species exhibited a strong association with their hosts. Zoonotic B. tribocorum, B. grahamii, B. elizabethae and B. rochalimae were found in synanthropic rodent species in southeastern China, which pose a potential threat to the public health. To prevent the spread of zoonotic Bartonella species to humans, preventive and control measures should be implemented, and more research is needed to confirm the pathogen's association with human disease.

Molecular investigation of tick-borne pathogens in ticks removed from tick-bitten humans in the southwestern region of the Republic of Korea

In this study, we investigated the presence of tick-borne pathogens in ticks removed from tick-bitten humans in the southwestern provinces of the Republic of Korea (ROK). We identified 33 ticks from three tick species, namely Amblyomma testudinarium (60.6%), Haemaphysalis longicornis (27.3%), and Ixodes nipponensis (12.1%) in order of occurrence via morphology and 16S rDNA-targeting polymerase chain reaction (PCR). Tick-borne pathogens were detected in 16 ticks using pathogen-specific PCR. From the results, 12 ticks (36.4%) tested positive for spotted fever group (SFG) Rickettsia: Rickettsia monacensis (1/12), R. tamurae (8/12), and Candidatus Rickettsia jingxinensis (3/12). Three ticks (9.1%) were positive for Anaplasma phagocytophilum. In addition, three ticks (9.1%) tested positive for Babesia gibsoni (1/3) and B. microti (2/3). In conclusion, we identified three tick species; the most common species was A. testudinarium, followed by H. longicornis and I. nipponensis. SFG Rickettsia, A. phagocytophilum, and Babesia spp. were the most frequently detected pathogens in ticks removed from tick-bitten humans. To our knowledge, this is the first report of R. tamurae and Ca. R. jingxinensis detection in Korea. The present results will contribute to the understanding of tick-borne infections in animals and humans in the ROK.

New Records of Bartonella spp. and Rickettsia spp. in Lice Collected from Small Rodents

Lice are blood-sucking insects that are of medical and veterinary significance as parasites and vectors for various infectious agents. More than half of described blood-sucking lice species are found on rodents. Rodents are important hosts of several Bartonella and Rickettsia species, and some of these bacteria are characterized as human pathogens in Europe. Rodent ectoparasites, such as fleas and ticks, are important vectors of Bartonella spp. and Rickettsia spp., but knowledge about the presence of these bacteria in lice is limited. The aim of this study was to determine the prevalence of Bartonella and Rickettsia bacteria in lice collected from rodents in Slovakia. The ectoparasites were collected from small rodents captured from 2010 to 2015 at four different sites in eastern Slovakia. The presence of Bartonella and Rickettsia species in lice samples was screened by real-time PCR, targeting ssrA and gltA genes, respectively. The molecular characterization of the Bartonella strains was based on sequence analysis of partial rpoB and intergenic spacer (ITS) genes, and of the Rickettsia species on sequence analysis of the gltA gene. A total of 1074 lice of seven species were collected from six rodent species. Bartonella DNA was detected in Hoplopleura affinis (collected from Apodemus agrarius, Apodemus flavicollis, and Myodes glareolus), Polyplax serrata (from A. agrarius), and Hoplopleura sp. (from A. flavicollis). Sequence analysis revealed that the Bartonella strains belonged to the Bartonella coopersplainsensis, Bartonella tribocorum, and Bartonella taylorii genogroups. Rickettsia DNA was detected in H. affinis and P. serrata collected from A. agrarius. Sequence analysis revealed two Rickettsia species: Rickettsia helvetica and Rickettsia sp. The results of the study confirm the presence of Bartonella spp. and Rickettsia spp. in lice collected from rodents.

Characterization of Bartonella taylorii Strains in Small Mammals of the Turkish Thrace

Rodents play role as a reservoir for some Bartonella species which cause different clinical manifestations in humans. Bartonella spp. existence in rodents of Turkish Thrace has been detected for the first time, and the risky habitat types were evaluated for the infection. Ninety individuals belonging to three small rodent species were screened by PCR, and the overall prevalence of Bartonella infection was 22.2%. The strains were characterized molecularly based on the phylogenetic analyses of two housekeeping genes, rpoB and gltA. They clustered with B. taylorii. The significant effects of habitat types and rodent species on Bartonella infections were observed. It was detected that B. taylorii prevalence was the highest in the swamp forest habitat and A. flavicollis species. The present study demonstrates that A. flavicollis is the reservoir of B. taylorii in the European part of Turkey.

Scalp eschar and neck lymphadenopathy after tick bite (SENLAT) caused by Bartonella henselae in Korea: a case report

Background

Tick-borne lymphadenopathy (TIBOLA) is an infectious disease, mainly caused by species from the spotted fever group rickettsiae and is characterized by enlarged lymph nodes following a tick bite. Among cases of TIBOLA, a case of scalp eschar and neck lymphadenopathy after tick bite (SENLAT) is diagnosed when an eschar is present on the scalp, accompanied by peripheral lymphadenopathy (LAP). Only a few cases of SENLAT caused by Bartonella henselae have been reported.

Case presentation

A 58-year-old male sought medical advice while suffering from high fever and diarrhea. Three weeks before the visit, he had been hunting a water deer, and upon bringing the deer home discovered a tick on his scalp area. Symptoms occurred one week after hunting, and a lump was palpated on the right neck area 6 days after the onset of symptoms. Physical examination upon presentation confirmed an eschar-like lesion on the right scalp area, and cervical palpation revealed that the lymph nodes on the right side were non-painful and enlarged at 2.5 × 1.5 cm. Fine needle aspiration of the enlarged lymph nodes was performed, and results of nested PCR for the Bartonella internal transcribed spacer (ITS) confirmed B. henselae as the causative agent.

Conclusion

With an isolated case of SENLAT and a confirmation of B. henselae in Korea, it is pertinent to raise awareness to physicians in other Asian countries that B. henselae could be a causative agent for SENLAT.

Prevalence and diversity of Bartonella species in small rodents from coastal and continental areas

Worldwide, Bartonella infections are known to inflict a wide range of mammals and, within rodents alone, more than 20 Bartonella species have been detected. There is, however, a lack of studies on the presence of Bartonella spp. in rodents in the Baltic region. We analysed 580 individuals belonging to eight small rodent species trapped in coastal and continental areas of Lithuania during 2015-2016. The presence of Bartonella DNA was examined by real-time PCR targeting the ssrA gene. The molecular characterization of the bacteria strains was based on sequence analysis of two housekeeping genes (rpoB, groEL) and the intergenic spacer region (ITS). For the rodents overall, the prevalence of Bartonella spp. was 54.8%, while the prevalence figures for each of the individual species were 8.3% in M. musculus, 15.8% in A. agrarius, 33.3% in M. arvalis, 42.4% in M. glareolus, 53.4% in M. oeconomus, 57.5% in M. minutus, 79.6% in A. flavicollis to 80% in M. agrestis. Sequence analysis revealed that the Bartonella strains belonged to the B. grahamii, B. taylorii, B. rochalimae, B. tribocorum, B. coopersplainsensis and B. doshiae genogroups. The highest Bartonella infection rates and the highest species diversity were both detected in rodents captured in the coastal area. To our knowledge, these are the first reports of the presence of B. coopersplainsensis, B. doshiae and B. tribocorum in Lithuania.

Bartonella Species, an Emerging Cause of Blood-Culture-Negative Endocarditis

Since the reclassification of the genus Bartonella in 1993, the number of species has grown from 1 to 45 currently designated members. Likewise, the association of different Bartonella species with human disease continues to grow, as does the range of clinical presentations associated with these bacteria. Among these, blood-culture-negative endocarditis stands out as a common, often undiagnosed, clinical presentation of infection with several different Bartonella species. The limitations of laboratory tests resulting in this underdiagnosis of Bartonella endocarditis are discussed. The varied clinical picture of Bartonella infection and a review of clinical aspects of endocarditis caused by Bartonella are presented. We also summarize the current knowledge of the molecular basis of Bartonella pathogenesis, focusing on surface adhesins in the two Bartonella species that most commonly cause endocarditis, B. henselae and B. quintana. We discuss evidence that surface adhesins are important factors for autoaggregation and biofilm formation by Bartonella species. Finally, we propose that biofilm formation is a critical step in the formation of vegetative masses during Bartonella-mediated endocarditis and represents a potential reservoir for persistence by these bacteria.

Genotyping ofBartonellabacteria and their animal hosts: current status and perspectives

Growing evidence demonstrates that bacterial species diversity is substantial, and many of these species are pathogenic in some contexts or hosts. At the same time, laboratories and museums have collected valuable animal tissue and ectoparasite samples that may contain substantial novel information on bacterial prevalence and diversity. However, the identification of bacterial species is challenging, partly due to the difficulty in culturing many microbes and the reliance on molecular data. Although the genomics revolution will surely add to our knowledge of bacterial systematics, these approaches are not accessible to all researchers and rely predominantly on cultured isolates. Thus, there is a need for comprehensive molecular analyses capable of accurately genotyping bacteria from animal tissues or ectoparasites using common methods that will facilitate large-scale comparisons of species diversity and prevalence. To illustrate the challenges of genotyping bacteria, we focus on the genusBartonella, vector-borne bacteria common in mammals. We highlight the value and limitations of commonly used techniques for genotyping bartonellae and make recommendations for researchers interested in studying the diversity of these bacteria in various samples. Our recommendations could be applicable to many bacterial taxa (with some modifications) and could lead to a more complete understanding of bacterial species diversity.

Genetic diversity of Bartonella genotypes found in the striped field mouse (Apodemus agrarius) in Central Europe

We investigated the diversity of Bartonella in Apodemus agrarius, an important rodent of peri-domestic habitats, which has spread into Europe in the past 1000 years. Spleen samples of 344 A. agrarius from Eastern Slovakia were screened for the presence of Bartonella spp. using 16S-23S rRNA internal transcribed spacer region and bacteria were detected in 9% of rodents. Based on sequencing of three housekeeping genes (gltA, rpoB and groEL) Bartonella genotypes were ascribed to the species typical for mice and voles: B. grahamii, B. taylorii and B. birtlesii. However, the study also confirmed presence of genotypes belonging to the B. clarridgeiae/B. rochalimae clade, and the B. elizabethae/B. tribocorum clade, which are not commonly found in woodland rodents. In addition, a potential recombination event between these two genotypes was noted, which highlights an important role of A. agrarius in shaping Bartonella diversity and evolution.