Detection of Rickettsia monacensis from Ixodes nipponensis collected from rodents in Gyeonggi and Gangwon Provinces, Republic of Korea

Molecular Identification of Spotted Fever Group Rickettsiae in Ticks in the Republic of Korea

The Rickettsia species transmitted by ticks are mostly classified within the spotted fever group rickettsiae (SFGR), which causes tick-borne rickettsiosis. Although efforts have been made to investigate their prevalence in the Republic of Korea (ROK), research has been limited to certain areas. Furthermore, the pooling method for ticks does not fully reflect the exact infection rate. Therefore, we aimed to perform molecular identification of SFGR in ticks to elucidate the current prevalence of tick-borne rickettsiosis in the ROK. The SFGR of ticks was identified using polymerase chain reaction targeting the 17 kDa antigen, ompA, and gltA, followed by sequencing for species identification and phylogenetic analysis. In total, 302 ticks belonging to four species (Haemaphysalis flava, H. longicornis, Ixodes nipponensis, and Amblyomma testudinarium) were collected between April and November 2022. The overall SFGR infection rate was 26.8% (81/302 patients). Both adult and nymphal ticks and the SFGR infection rate increased during April-May, reaching their peaks in June, followed by a marked decline in August and July, respectively. Phylogenetic analysis revealed three species (R. monacensis, R. heilongjiangensis, and Candidatus R. jingxinensis) of SFGR. Thus, our results emphasize the importance of tick surveys for the prevention and management of tick-borne rickettsiosis.

Distribution and pathogen prevalence of field-collected ticks from south-western Korea: a study from 2019 to 2022

Hard ticks are known vectors of various pathogens, including the severe fever with thrombocytopenia syndrome virus, Rickettsia spp., Coxiella burnetii, Borrelia spp., Anaplasma phagocytophilum, and Ehrlichia spp. This study aims to investigate the distribution and prevalence of tick-borne pathogens in southwestern Korea from 2019 to 2022. A total of 13,280 ticks were collected during the study period, with H. longicornis accounting for 86.1% of the collected ticks. H. flava, I. nipponensis and A. testudinarium comprised 9.4%, 3.6%, and 0.8% of the ticks, respectively. Among 983 pools tested, Rickettsia spp. (216 pools, 1.6% MIR) were the most prevalent pathogens across all tick species, with R. japonica and R. monacensis frequently detected in I. nipponensis and Haemaphysalis spp., respectively. Borrelia spp. (28 pools, 0.2% MIR) were predominantly detected in I. nipponensis (27 pools, 13.8% MIR, P < 0.001). Co-infections, mainly involving Rickettsia monacensis and Borrelia afzelii, were detected in I. nipponensis. Notably, this study identified R. monacensis for the first time in A. testudinarium in South Korea. These findings offer valuable insights into the tick population and associated pathogens in the region, underscoring the importance of tick-borne disease surveillance and prevention measures.

Distribution and Prevalence of Anaplasmataceae, Rickettsiaceae and Coxiellaceae in African Ticks: A Systematic Review and Meta-Analysis

In Africa, ticks continue to be a major hindrance to the improvement of the livestock industry due to tick-borne pathogens that include Anaplasma, Ehrlichia, Rickettsia and Coxiella species. A systemic review and meta-analysis were conducted here and highlighted the distribution and prevalence of these tick-borne pathogens in African ticks. Relevant publications were searched in five electronic databases and selected using inclusion/exclusion criteria, resulting in 138 and 78 papers included in the qualitative and quantitative analysis, respectively. Most of the studies focused on Rickettsia africae (38 studies), followed by Ehrlichia ruminantium (27 studies), Coxiella burnetii (20 studies) and Anaplasma marginale (17 studies). A meta-analysis of proportions was performed using the random-effects model. The highest prevalence was obtained for Rickettsia spp. (18.39%; 95% CI: 14.23–22.85%), R. africae (13.47%; 95% CI: 2.76–28.69%), R. conorii (11.28%; 95% CI: 1.77–25.89%), A. marginale (12.75%; 95% CI: 4.06–24.35%), E. ruminantium (6.37%; 95% CI: 3.97–9.16%) and E. canis (4.3%; 95% CI: 0.04–12.66%). The prevalence of C. burnetii was low (0%; 95% CI: 0–0.25%), with higher prevalence for Coxiella spp. (27.02%; 95% CI: 10.83–46.03%) and Coxiella-like endosymbionts (70.47%; 95% CI: 27–99.82%). The effect of the tick genera, tick species, country and other variables were identified and highlighted the epidemiology of Rhipicephalus ticks in the heartwater; affinity of each Rickettsia species for different tick genera; dominant distribution of A. marginale, R. africae and Coxiella-like endosymbionts in ticks and a low distribution of C. burnetii in African hard ticks.

Seasonal activity of Haemaphysalis longicornis and Haemaphysalis flava (Acari: Ixodida), vectors of severe fever with thrombocytopenia syndrome (SFTS) virus, and their SFTS virus harboring rates in Gyeonggi Province, South Korea

Seasonal activity of ticks, including disease vectors of fatal severe fever with thrombocytopenia syndrome (SFTS) virus, was monitored using CO₂-bait traps from April to November in 2019 and 2020 in a rural area in Gyeonggi-do, South Korea. Traps were deployed for 24 h once a month in four vegetation types: grassland, grave, mountain trail, and shrubs. A total of 4516 ticks were caught, all of which belong to the genus Haemaphysalis; larvae, nymphs, and adults were 41.9, 39.5, and 18.6%, respectively. The nymphs and adults belonged to two tick species, H. longicornis and H. flava, and H. longicornis was dominant, comprising 97.9% of the two stages collected. Larvae were identified only to the genus level due to difficulty of morphological distinction between species. For H. longicornis, nymph numbers peaked between April and June, followed by adults between June and July. Haemaphysalis larvae showed clear peaks in August. In general, H. longicornis nymphs and adults were most abundant in grassland, whereas larvae were so in the grave area. Collected ticks were pooled and subjected to PCR analysis to estimate SFTS virus harboring rate. In 2019, only one SFTS virus-positive sample was detected in June. However, a total of 18 SFTS-virus positive samples were detected from August to October in 2020.

Identification of Babesia capreoli from Korean Water Deer in the Republic of Korea

Babesiosis is a tick-borne disease caused by intraerythrocytic protozoa belonging to the genus Babesia that is primarily transmitted through Ixodid ticks and is highly pathogenic to ruminants, horses, pigs, dogs, cats, and in some cases, even humans. Babesia is considered an increasing threat to animal and human health. In this study we report Babesia capreoli infection in Korean water deer (Hydropotes inermis argyropus). Blood samples of 77 wild animals (62 Korean water deer and 15 Korean raccoon dogs [Nyctereutes procyonoides koreensis]) were analyzed to detect Babesia infection. First, PCR was performed to investigate Babesia infection using the partial 18S rRNA gene. Among the 77 wild animals examined, 11 Korean water deer were positive for infection as per the results of sequence analysis. Next, these 11 samples were reanalyzed by PCR using newly designed primers to differentiate between B. capreoli and Babesia divergens. Finally, only one Korean water deer sample was found to be positive for B. capreoli. The nucleotide sequence of this protozoan showed 99.6 - 99.7% identity to those of B. capreoli reported previously. Phylogenetic analysis revealed that the sequence belonged to the B. capreoli clade and diverged from the B. divergens clade. Three nucleotides at positions 631, 663, and 1637 were analyzed to differentiate between B. capreoli and B. divergens. The nucleotides at positions 631 and 1637 were identical to those of B. capreoli, whereas that at position 663 was different. The sequence detected in Korean water deer also exhibited differences at other four positions (669, 704, 711, and 1661) compared with other B. capreoli sequences. This study indicates that Korean water deer serve as a reservoir for B. capreoli. In addition, the primers designed in this study can be used to detect B. capreoli. Future studies should explore the tick vectors that transmit B. capreoli and its pathogenicity. This study was approved by the Institutional Committee of Graduate Studies and Research at Jeonbuk National University, ROK (IACUC decision no.: CBU 2014-00026).

Surveillance and Molecular Identification of Borrelia Species in Ticks Collected at U.S. Army Garrison Humphreys, Republic of Korea, 2018-2019

Tick-borne pathogens are contributing factors for the increased incidence of vector-borne diseases throughout the world, including Lyme borreliosis, one of the most prevalent spirochetes belonging to the Borrelia burgdorferi sensu lato group. The present study focused on the detection of Borrelia species from hard ticks collected at U.S. Army Garrison Humphreys, Republic of Korea (ROK), using molecular and genotypic analyses. Tick-borne disease surveillance was conducted from January to December, 2018-2019. A total of 24,281 ticks (2 genera and 5 species) were collected from road-killed Korean Water deer (KWD) and by tick drag. Haemaphysalis longicornis (92.0%) was the most commonly collected species, followed by Haemaphysalis flava (4.9%), Ixodes nipponensis (3.1%), Haemaphysalis phasiana (0.07%), and Haemaphysalis japonica (<0.01%). The ospA gene sequences of Borrelia afzelii were detected in 12/529 pools of I. nipponensis. Three and one pools were positive for B. afzelii and Borrelia miyamotoi, respectively, using the 16s rRNA gene. None of the pools of Haemaphysalis ticks collected from KWD or by tick drag were positive for Borrelia species. I. nipponensis was collected throughout the year from KWD and from February to November by tick drag, suggesting that they were active throughout the year, and expanding the risk period for acquiring Lyme borreliosis and Borrelia relapsing fever in the ROK. This study assessed disease risk factors associated with the prevalence of Lyme disease in ticks collected from KWD and by tick drag using molecular analysis. These results provide an understanding and awareness into the prevalence and molecular characteristics of Borrelia species in the ROK.

Molecular evidence of zoonotic Babesia species, other than B. microti, in ixodid ticks collected from small mammals in the Republic of Korea

The occurrence of tick‐borne infectious diseases, including zoonotic babesiosis, has become a serious concern in recent years. In this study, we detected Babesia spp. using polymerase chain reaction (PCR) amplification of the 18S rRNA of the parasites isolated from ixodid ticks collected from small mammals in the Republic of Korea (ROK). Sequence analysis of the PCR amplicon revealed the presence of B. duncani, B. venatorum, B. capreoli/divergens, and, the most prevalent, B. microti in the ticks. The molecular phylogenetic analysis showed that the four species‐specific18S rRNA sequences clustered in four distinct clades. This is the first study to provide molecular evidence for the presence of zoonotic Babesia spp. other than B. microti in ticks in the ROK.

Detection of Rickettsia lusitaniae Among Ornithodoros sawaii Soft Ticks Collected From Japanese Murrelet Seabird Nest Material From Gugul Island, Republic of Korea

In a follow-up to the investigations of soft ticks identified from seabird nest soil and litter collected from coastal islands of the Republic of Korea (ROK), Ornithodoros sawaii and Ornithodoros capensis were assessed for the presence and identification of rickettsiae. Ticks collected from samples of 50-100 g of nest litter and soil from seabird nests were identified individually by morphological techniques, and species confirmed by sequencing of the mt-rrs gene. Subsequently, tick DNA preparations were screened for the presence of rickettsiae using a genus-specific nested PCR (nPCR) assay targeting the 17 kDa antigen gene. The amplicons from the 17 kDa assay and two additional nPCR assays targeting the gltA and ompB gene fragments were sequenced and used to identify the rickettsiae. A total of 134 soft ticks belonging to two species, O. sawaii Kitaoka & Suzuki 1973 (n = 125) and O. capensis Neumann 1901 (n = 9), were collected. Rickettsia lusitaniae DNA was detected and identified among O. sawaii ticks (n = 11, 8.8%) collected from nest litter and soil of the Japanese murrelet (Synthliboramphus wumizusume Temminck 1836) at Gugul Island along the western coastal area of the ROK. This study confirmed for the first time the presence of R. lusitaniae associated with O. sawaii collected from migratory seabird nests in the ROK.

Molecular genetic analysis and clinical characterization of Rickettsia species isolated from the Republic of Korea in 2017

Rickettsia sp. CNH17-7 was isolated from patients' blood and identified by gene analysis as a species distinct from Rickettsia japonica. In addition, similar rickettsial infection was confirmed in two species (Haemaphysalis longicornis and Ixodes nipponensis) of ticks and rodents in northeastern and southwestern provinces, Republic of Korea. Subsequently, the analysis of 16S rRNA, ompA, ompB and sca4 genes of isolate CNH17-7 revealed 100%, 99.68%, 99.57% and 99.44% sequence similarity with Rickettsia sp. HlR/D91 and Candidatus R. longicornii ROK-HL727. In this study, we report the isolation of a new Rickettsia sp. CNH17-7 and infection of different types of ticks with the same rickettsial agents.

Detection of Borrelia miyamotoi in Ixodes nipponensis in Korea

Background

This study investigated Borrelia species prevalence in ticks from vegetation, through a molecular method, in Gwangju Metropolitan City, South Korea.

Methodology/Principal findings

A total of 484 ticks were collected through flagging and dragging in a suburban area of Gwangju Metropolitan City, South Korea, in 2014. These ticks were morphologically identified and subjected to nested PCR, targeting Borrelia–specific CTP synthase (pyrG), outer surface protein A (ospA) and flagellin (flaB) genes. Molecular biological species identification of Borrelia-positive ticks was conducted via 16S rRNA PCR assays. Of the 484 ticks collected, 417 (86.2%) were identified as Haemaphysalis longicornis, 42 (8.7%) as H. flava, and 25 (5.2%) as Ixodes nipponensis. All the ixodid ticks containing Borrelia species bacteria were confirmed to be I. nipponensis adults, by both morphological and molecular methods. Of the 25 I. nipponensis ticks collected, four (16%) were positive for Borrelia species, three of which were B. afzelii and one B. miyamotoi.

Conclusions/Significance

Our study has shown the harboring of B. miyamotoi by I. nipponensis in South Korea. Morphological and molecular genetic analyses revealed that, in South Korea, I. nipponensis could potentially transmit B. miyamotoi to humans.

Diversity of spotted fever group rickettsiae and their association with host ticks in Japan

Spotted fever group (SFG) rickettsiae are obligate intracellular Gram-negative bacteria mainly associated with ticks. In Japan, several hundred cases of Japanese spotted fever, caused by Rickettsia japonica, are reported annually. Other Rickettsia species are also known to exist in ixodid ticks; however, their phylogenetic position and pathogenic potential are poorly understood. We conducted a nationwide cross-sectional survey on questing ticks to understand the overall diversity of SFG rickettsiae in Japan. Out of 2,189 individuals (19 tick species in 4 genera), 373 (17.0%) samples were positive for Rickettsia spp. as ascertained by real-time PCR amplification of the citrate synthase gene (gltA). Conventional PCR and sequencing analyses of gltA indicated the presence of 15 different genotypes of SFG rickettsiae. Based on the analysis of five additional genes, we characterised five Rickettsia species; R. asiatica, R. helvetica, R. monacensis (formerly reported as Rickettsia sp. In56 in Japan), R. tamurae, and Candidatus R. tarasevichiae and several unclassified SFG rickettsiae. We also found a strong association between rickettsial genotypes and their host tick species, while there was little association between rickettsial genotypes and their geographical origins. These observations suggested that most of the SFG rickettsiae have a limited host range and are maintained in certain tick species in the natural environment.

Molecular Identification of Rickettsia Species in Haemaphysalis Ticks Collected from Southwest China

Rickettsia species are obligate intracellular Gram-negative bacteria that can infect a wide range of vertebrate hosts, including humans, through arthropod vectors such as Ixodid ticks. These ticks are a threat to humans and animals because they are the primary vectors or reservoirs for rickettsiae, which is of public health importance. In this study, we report the identification and percent of positive of Rickettsia spp. in ticks collected from Cangxi County, Southwest China. Haemaphysalis longicornis comprised 48.4% of the 188 ticks collected followed by Haemaphysalis flava (29.3%), H. doenitzi (12.2%), and Haemaphysalis hystricis (10.1%). A total of 63 (33.5%) ticks were positive with Rickettsia spp., with 48 (57%) of those being H. longicornis and 15 (27.3%) being H. flava. The other two tick species, however, did not have any ticks positive for rickettsial DNA. In addition, two different Rickettsia spp. were identified using gltA and ompA as molecular markers. The sequence of Rickettsia sp. infecting H. longicornis ticks was found to be identical to the Rickettsia sequences from Northeastern China and Japan (KF728367, AB516964). Phylogenetic analyses using these molecular markers support the notion that Rickettsia species from H. flava is the most close to a member of the Candidatus Rickettsia gannanii subgroup. The high percentage of Rickettsia positive in this Southwest China region suggests potential public health threat in the future and warrants to be monitored.

Detection of Rickettsia monacensis and Rickettsia amblyommatis in ticks collected from dogs in Costa Rica and Nicaragua

The neotropical climate of Central America provides ideal conditions for ticks, which may transmit several human pathogens, including spotted-fever group Rickettsia. Dogs may act as sentinels or reservoirs for human tick-borne diseases due to shared tick species. Here, ticks were collected from 680 client-owned dogs in Nicaragua and Costa Rica, and a total of 316 tick pools were investigated for Rickettsia infection by quantitative real-time PCR (qPCR) targeting the gltA gene. Subsequently, up to six further genomic targets (16S rDNA, gltA, sca4, ompA, ompB and the 23S-5S intergenic spacer) were investigated for Rickettsia species determination. The predominant tick species was Rhipicephalus sanguineus sensu lato (s.l.) (19.9% of dogs infested in Costa Rica, 48.0% in Nicaragua), followed by Ixodes boliviensis (3.1% in Costa Rica / none in Nicaragua) and Amblyomma ovale (4.8% in Costa Rica, 0.9% in Nicaragua). In total, 22 of 316 tick pools containing 60 of 1023 individual ticks were Rickettsia-positive as determined by qPCR, resulting in a minimum infection rate (MIR) of 2.2%. In detail, MIR in Rh. sanguineus s.l. was 0.7% (7/281 pools), in I. boliviensis 33.3% (12/13 pools) and in A. ovale 9.7% (3/22 pools). For 11 of 12 positive I. boliviensis pools and one of six positive Rh. sanguineus s.l. pools, the species could be determined as R. monacensis. R. amblyommatis was identified in one Rh. sanguineus s.l. pool from Costa Rica and one A. ovale pool from Nicaragua. Nine of 12 R. monacensis-positive tick pools were collected in San Rafael de Heredia, Costa Rica, indicating a high local occurrence in this area. This study supports recent evidence that R. monacensis is present on the American continent. Its high local occurrence among dog-associated I. boliviensis, which may also parasitize humans, in Costa Rica gives cause for concern, as R. monacensis is also pathogenic to humans.

Tick-borne pathogens in ticks collected from birds in Taiwan

Background

A variety of human diseases transmitted by arthropod vectors, including ticks, are emerging around the globe. Birds are known to be hosts of ticks and can disperse exotic ticks and tick-borne pathogens. In Taiwan, previous studies have focused predominantly on mammals, leaving the role of birds in the maintenance of ticks and dissemination of tick-borne pathogens undetermined.

Methods

Ticks were collected opportunistically when birds were studied from 1995 to 2013. Furthermore, to improve knowledge on the prevalence and mean load of tick infestation on birds in Taiwan, ticks were thoroughly searched for when birds were mist-netted at seven sites between September 2014 and April 2016 in eastern Taiwan. Ticks were identified based on both morphological and molecular information and were screened for potential tick-borne pathogens, including the genera Anaplasma, Babesia, Borrelia, Ehrlichia and Rickettsia. Finally, a list of hard tick species collected from birds in Taiwan was compiled based on past work and the current study.

Results

Nineteen ticks (all larvae) were recovered from four of the 3096 unique mist-netted bird individuals, yielding a mean load of 0.006 ticks/individual and an overall prevalence of 0.13%. A total of 139 ticks from birds, comprising 48 larvae, 35 nymphs, 55 adults and one individual of unknown life stage, were collected from 1995 to 2016, and 11 species of four genera were identified, including three newly recorded species (Haemaphysalis wellingtoni, Ixodes columnae and Ixodes turdus). A total of eight tick-borne pathogens were detected, with five species (Borrelia turdi, Anaplasma sp. clone BJ01, Ehrlichia sp. BL157-9, Rickettsia helvetica and Rickettsia monacensis) not previously isolated in Taiwan. Overall, 16 tick species of five genera have been recorded feeding on birds, including nine species first discovered in this study.

Conclusion

Our study demonstrates the paucity of information on ticks of birds and emphasizes the need for more research on ticks of birds in Taiwan and Southeast Asia. Moreover, some newly recorded ticks and tick-borne pathogens were found only on migratory birds, demonstrating the necessity of further surveillance on these highly mobile species.

Electronic supplementary material

The online version of this article (10.1186/s13071-017-2535-4) contains supplementary material, which is available to authorized users.

John H, Jarman RG, Hang J, Richards AL. Molecular characterization of novel mosquito-borne Rickettsia spp. from mosquitoes collected at the Demilitarized Zone of the Republic of Korea

Rickettsiae are associated with a diverse range of invertebrate hosts. Of these, mosquitoes could emerge as one of the most important vectors because of their ability to transmit significant numbers of pathogens and parasites throughout the world. Recent studies have implicated Anopheles gambiae as a potential vector of Rickettsia felis. Herein we report that a metagenome sequencing study identified rickettsial sequence reads in culicine mosquitoes from the Republic of Korea. The detected rickettsiae were characterized by a genus-specific quantitative real-time PCR assay and sequencing of rrs, gltA, 17kDa, ompB, and sca4 genes. Three novel rickettsial genotypes were detected (Rickettsia sp. A12.2646, Rickettsia sp. A12.2638 and Rickettsia sp. A12.3271), from Mansonia uniformis, Culex pipiens, and Aedes esoensis, respectively. The results underscore the need to determine the Rickettsia species diversity associated with mosquitoes, their evolution, distribution and pathogenic potential.

Francisella-Like Endosymbiont Detected in Haemaphysalis Ticks (Acari: Ixodidae) From the Republic of Korea

A total of 6,255 ticks belonging to three genera and six species (Haemaphysalis flava Neumann, Haemaphysalis longicornis Neumann, Haemaphysalis phasiana Saito, Ixodes nipponensis Kitaoka & Saito, Ixodes persulcatus Schulze, and Amblyomma testudinarium Koch) collected from May-August, 2013, at four southwestern provinces in the Republic of Korea (ROK) were submitted to the Armed Forces Research Institute of Medical Sciences and assayed for selected tick-borne pathogens. One pool each of H. flava and H. phasiana was positive by PCR and sequencing for a Francisella-like endosymbiont, while all pools were negative for Francisella tularensis, the causative agent of tularemia.

First isolation of Rickettsia monacensis from a patient in South Korea

A Rickettsia sp. was isolated from the blood of a patient with an acute febrile illness using the shell vial technique; the isolate was named CN45Kr and was identified by molecular assay as Rickettsia monacensis, which was first recognized as a pathogen in Spain. Sequencing analysis showed that the gltA sequence of the isolate was identical to that of Rickettsia sp. IRS3. The ompA-5mp fragment sequence showed 100% identity to those of R. monacensis and Rickettsia sp. In56 and ompA-3pA In56 and 100% identity to that of Rickettsia sp. IRS3. The ompB sequence was found to have 99.9% similarity to that of R. monacensis IrR/Munich. This study confirms the pathogenicity of this agent and provides additional information about its geographic distribution.

Molecular detection of Rickettsia species in ticks collected from the southwestern provinces of the Republic of Korea

Background

Rickettsiae constitute a group of arthropod-borne, Gram-negative, obligate intracellular bacteria that are the causative agents of diseases ranging from mild to life threatening that impact on medical and veterinary health worldwide.

Methods

A total of 6,484 ticks were collected by tick drag from June-October 2013 in the southwestern provinces of the Republic of Korea (ROK) (Jeollanam, n = 3,995; Jeollabuk, n = 680; Chungcheongnam, n = 1,478; and Chungcheongbuk, n = 331). Ticks were sorted into 311 pools according to species, collection site, and stage of development. DNA preparations of tick pools were assayed for rickettsiae by 17 kDa antigen gene and ompA nested PCR (nPCR) assays and the resulting amplicons sequenced to determine the identity and prevalence of spotted fever group rickettsiae (SFGR).

Results

Haemaphysalis longicornis (4,471; 52 adults, 123 nymphs and 4,296 larvae) were the most commonly collected ticks, followed by Haemaphysalis flava (1,582; 28 adults, 263 nymphs and 1,291 larvae), and Ixodes nipponensis (431; 25 adults, 5 nymphs and 401 larvae). The minimum field infection rate/100 ticks (assuming 1 positive tick/pool) was 0.93% for the 17 kDa antigen gene and 0.82% for the ompA nPCR assays. The partial 17 kDa antigen and ompA gene sequences from positive pools of H. longicornis were similar to: Rickettsia sp. HI550 (99.4–100%), Rickettsia sp. FUJ98 (99.3–100%), Rickettsia sp. HIR/D91 (99.3–100%), and R. japonica (99.7%). One sequence of the partial 17 kDa antigen gene for H. flava was similar to Rickettsia sp. 17kd-005 (99.7%), while seven sequences of the 17 kDa antigen gene obtained from I. nipponensis ticks were similar to R. monacensis IrR/Munich (98.7–100%) and Rickettsia sp. IRS3 (98.9%).

Conclusions

SFG rickettsiae were detected in three species of ixodid ticks collected in the southwestern provinces of the ROK during 2013. A number of rickettsiae have been recently reported from ticks in Korea, some of which were identified as medically important. Results from this study and previous reports demonstrate the need to conduct longitudinal investigations to identify tick-borne rickettsiae and better understand their geographical distributions and potential impact on medical and veterinary health, in addition to risk communication and development of rickettsial disease prevention strategies.

Detection of SFTS Virus in Ixodes nipponensis and Amblyomma testudinarium (Ixodida: Ixodidae) Collected From Reptiles in the Republic of Korea

A survey of reptile-associated ticks and their infection status with severe fever with thrombocytopenia syndrome (SFTS) virus was conducted to determine the relative abundance and distribution among lizards, skinks, and snakes in the Republic of Korea (ROK). In total, 132 reptiles, including 49 lizards (two species), 15 skinks (one species), and 68 snakes (eight species) were collected. In total, 84 ixodid ticks belonging to two genera (Ixodes and Amblyomma) were collected from 28/132 (21.2%) lizards, skinks, and snakes. Ixodes nipponensis Kitaoka & Saito was only collected from lizards and skinks, while Amblyomma testudinarium Koch was only collected from snakes. Takydromus wolteri had the highest tick index (0.7; total number ticks/total number collected hosts) among lizards and skinks, while Rhabdophis tigrinus had the highest tick index (2.2) among the snakes. Ixodes nipponensis larvae and nymphs accounted for 11.1% and 88.9%, respectively, of all ticks collected from lizards and skinks, while only A. testudinarium nymphs were collected from snakes. Nymphs of both species of ticks were collected from lizards and skinks from April to October, while I. nipponensis larvae were collected only from September to October. Ixodes nipponensis larvae and nymphs were preferentially attached to the lateral trunk (83.3%) and the foreleg axillae (16.7%) of lizards and skinks. SFTS virus was detected in both I. nipponensis and A. testudinarium collected from lizards and snakes. Phylogenetic analysis of SFTS viruses of ticks collected from two lizards and one snake demonstrated close relationships with SFTS virus strains observed from humans and ticks in the ROK, China, and Japan. These results implicate lizards and snakes as potential hosts of SFTS virus.

Rickettsia buchneri sp. nov., a rickettsial endosymbiont of the blacklegged tick Ixodes scapularis

We obtained a rickettsial isolate from the ovaries of the blacklegged tick, Ixodes scapularis. The isolate (ISO7(T)) was grown in the Ixodes ricinus embryonic cell line IRE11. We characterized the isolate by transmission electron microscopy and gene sequencing. Phylogenetic analysis of 11 housekeeping genes demonstrated that the isolate fulfils the criteria to be classified as a representative of a novel rickettsial species closely related to 'Rickettsia monacensis'. These rickettsiae form a clade separate from other species of rickettsiae. Gene sequences indicated that several genes important in rickettsial motility, invasiveness and temperature adaptation were mutated (e.g. sca2, rickA, hsp22, pldA and htrA). We propose the name Rickettsia buchneri sp. nov. for this bacterium that infects the ovaries of the tick I. scapularis to acknowledge the pioneering contributions of Professor Paul Buchner (1886-1978) to research on bacterial symbionts. The type strain of R. buchneri sp. nov. is strain ISO-7(T) ( = DSM 29016(T) = ATCC VR-1814(T)).

Vector competence of the tick Ixodes sinensis (Acari: Ixodidae) for Rickettsia monacensis

BACKGROUND

Cases of Mediterranean Spotted Fever like rickettsioses, caused by Rickettsia monacensis, have become more common in the last 10 years. In China, natural infection of R. monacensis in various tick species has been confirmed but the vector(s) of R. monacensis have not been recorded.

METHODS

The prevalence of R. monacensis in >1500 Ixodidae ticks from central and southern China was determined using centrifugation-shell vial culture and polymerase chain reaction techniques. The predominant species, Ixodes sinensis, harbored a natural infection of R. monacensis and was assumed to be a vector candidate of R. monacensis. Experimental transmissions were initialized by infecting Rickettsia-free tick colonies with R. monacensis using capillary tube feeding (CTF) or immersion techniques. Transstadial and transovarial transmissions, and transmission from ticks to mice, were conducted under laboratory conditions.

RESULTS

R. monacensis was isolated and identified from hemolymph of Ixodes sinensis using molecular techniques. Transovarial transmission of R. monacensis from infected ♀I. sinensis to offspring was documented and infected offspring successfully passed Rickettsia to mice. Transstadial transmission rates were 58% in larva to nymph and 56% in nymph to adult stages. Infected nymphs and adults were also able to infect mice.

CONCLUSIONS

I. sinensis is a competence vector for R. monacensis as demonstrated by natural infection and transmission studies.

Ticks collected from wild and domestic animals and natural habitats in the Republic of Korea

Ticks were collected from 35 animals from 5 provinces and 3 metropolitan cities during 2012. Ticks also were collected by tick drag from 4 sites in Gyeonggi-do (2) and Jeollabuk-do (2) Provinces. A total of 612 ticks belonging to 6 species and 3 genera were collected from mammals and a bird (n=573) and by tick drag (n=39). Haemaphyalis longicornis (n=434) was the most commonly collected tick, followed by H. flava (158), Ixodes nipponensis (11), Amblyomma testudinarium (7), H. japonica (1), and H. formosensis (1). H. longicornis and H. flava were collected from all animal hosts examined. For animal hosts (n>1), the highest Tick Index (TI) was observed for domestic dogs (29.6), followed by Siberian roe deer (17.4), water deer (14.4), and raccoon dogs (1.3). A total of 402 H. longicornis (adults 86, 21.4%; nymphs 160, 39.8%; larvae 156, 38.9%) were collected from wild and domestic animals. A total of 158 H. flava (n=158) were collected from wild and domestic animals and 1 ring-necked pheasant, with a higher proportion of adults (103, 65.2%), while nymphs and larvae only accounted for 12.7% (20) and 22.2% (35), respectively. Only 7 A. testudinarium were collected from the wild boar (6 adults) and Eurasian badger (1 nymph), while only 5 I. nipponensis were collected from the water deer (4 adults) and a raccoon dog (1 adult). One adult female H. formosensis was first collected from vegetation by tick drag from Mara Island, Seogwipo-si, Jeju-do Province.