Molecular Identification of Borrelia afzelii from Ticks Parasitizing Domestic and Wild Animals in South Korea

Tick Control Strategies: Critical Insights into Chemical, Biological, Physical, and Integrated Approaches for Effective Hard Tick Management

Ticks and tick-borne diseases significantly impact animal health, public health, and economic productivity globally, particularly in areas where the wildlife-livestock interface complicates management. This review critically examines the current control strategies, focusing on chemical, biological, physical, and integrated pest management (IPM) approaches. Chemical acaricides, while effective, are increasingly challenged by resistance development and environmental concerns. Biological approaches, including natural predators and entomopathogenic fungi, and physical interventions, such as habitat modification, provide sustainable alternatives but require further optimization. IPM stands out as the most promising long-term solution, integrating multiple approaches to enhance efficacy while reducing environmental risks. Emerging innovations, such as nanotechnology-enhanced acaricides and next-generation vaccines, offer promising avenues for improved tick control. Addressing the complex challenges of tick management requires tailored strategies, interdisciplinary collaboration, and sustained research investment in both veterinary and public health contexts.

Tick-borne pathogens in Mongolian ticks: The high prevalence of Rickettsia raoultii and its public health implications

In Mongolia, a substantial segment of the population is engaged in pastoralism, leading to frequent interactions with livestock and heightened exposure to tick-infested environments. Consequently, ticks and the endemic tick-borne pathogens (TBPs) they harbor present significant health threats. In May 2021, we conducted a study to evaluate the prevalence of 9 TBPs in ticks collected from four regions in Mongolia: Uvurkhangai, Tuv, Bayan-Ulgii, and Khentii. The pathogens surveyed included Anaplasma, Rickettsia, Bartonella, Borrelia, Ehrlichia, Babesia, Toxoplasma, Theileria, and lumpy skin disease virus. Molecular analysis of 1142 ticks revealed that, although the majority of TBPs were not detected, 89.1 % of the ticks were positive for Rickettsia. Genetic characterization using the 16S rRNA and gltA genes identified the pathogen identified the pathogen Rickettsia raoultii. Species identification indicated a predominance of Dermacentor nuttalli (70.0 %) and Dermacentor silvarum (30.0 %). These findings highlight the extensive prevalence of R. raoultii in Mongolia and underscore the urgent need for heightened awareness and preventive measures due to the high level of interaction between livestock and humans. The genetic similarity of R. raoultii sequences to those found in neighboring countries suggests potential cross-border transmission, underscoring the importance of conducting similar research in surrounding regions. This study advances our understanding of the epidemiology of tick-borne diseases in Mongolia and can inform public health strategies aimed at mitigating the risks associated with these infections.

Surveillance of Vector-Borne Zoonotic Diseases in South Korea: Uncovering Novel Pathogen Carriers Among Rodents and Mites Nationwide

Wild rodents and their ectoparasites are known reservoirs for various zoonotic pathogens, highlighting the need for detailed studies into their roles in disease transmission. Our research investigated the spatial distribution of rodents and their ectoparasites to better understand the epidemiology of vector-borne zoonotic diseases (VBZDs), including severe fever with thrombocytopenia syndrome (SFTS), Lyme disease, Q fever, and scrub typhus. We analyzed samples from 540 rodents and 6785 mites, detecting the presence of Borrelia spp., the causative agent of Lyme disease, in 0.9% of rodents and SFTS virus (SFTSV) in 1.0%. In mites, Borrelia spp. and Orientia tsutsugamushi, the bacteria causing scrub typhus, were detected in 0.3% of samples each. Phylogenetic analysis identified the SFTSV sequence as type B3, the Borrelia spp. sequence as B. afzelii, and the O. tsutsugamushi sequence as Karp-related. Notably, SFTSV was detected for the first time in mites in South Korea, and B. afzelii was found in mites for the first time globally. These findings emphasize the critical need for continuous analysis of VBZDs to anticipate future trends and develop a comprehensive monitoring system. Further research into the rodent and mite populations in South Korea is essential to fully assess the potential risks of VBZDs.

An Updated Review on the Spatial Distribution of Borrelia burgdorferi Sensu Lato Across Ticks, Animals and Humans in Northeastern China and Adjacent Regions

BACKGROUND

Lyme disease is a tick-borne zoonotic disease caused by Borrelia burgdorferi sensu lato and is prevalent in northeastern Asia, particularly in the forested area of Northeastern China. However, a lack of systematic data on the spatial distribution of B. burgdorferi in this region hinders the prediction of its transmission risk across the landscape.

METHODS

To provide an updated overview and establish a comprehensive spatial distribution database, we conducted a systematic review of literature published between 2000 and 2022. We collected and compiled relevant data on B. burgdorferi in Northeastern China and its neighbouring regions, outlining its distribution in ticks, wild animals, livestock and humans. Spatial analysis was performed to identify spatial clusters of tick positivity and host infection rates.

RESULTS

From a total of 1823 literature, we selected 110 references to compile 626 detection records of B. burgdorferi, including 288 in ticks, 109 in wildlife, 111 in livestock and domestic animals and 100 in humans. The average detection rate of B. burgdorferi in ticks was approximately 20%, with wildlife, livestock and domestic animal host positivity rates below 50% and human seroprevalence rates varying from 0.94% to 44.18%.

CONCLUSIONS

The study identified the presence of 17 tick species and ten genotypes of B. burgdorferi in the region, indicating a broad distribution. Notably, B. burgdorferi exhibited notable clustering, particularly in the central and eastern areas of Jilin Province, warranting further investigation.

Molecular detection and phylogenetic analysis of Borrelia Spp. In blood samples of cats and dogs by the nested-PCR method in West Azerbaijan Province, Iran

The objective of this study was to investigate the presence and genetic attributes of Borrelia spp. in cats and dogs from the West Azerbaijan Province, located in the northwest of Iran. A total of 250 blood samples from cats and 300 blood samples from dogs were collected, and information regarding their age, sex, breed, ownership status, sampling time and region was recorded. The identification of positive samples was accomplished through nested-PCR and sequencing, with subsequent analysis of the gene sequences conducted using BioEdit software. The gene sequences for Borrelia spp. in this study showed 100% similarity to reference sequences in the GenBank® database. Phylogenetic trees were built using MEGA11. The outcomes indicated that among 250 blood samples from cats, 48 (19.2%) tested positive for Borrelia spp. gene, with a CI from 14.8 to 24.53% for cats. Similarly, out of 300 blood samples from dogs, 45 (15%) tested positive for the Borrelia spp. gene, with a CI from 11.4 to 19.48% for dogs.

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.

Molecular analysis of Rickettsia spp. and related tick-borne pathogens detected in dogs in Korea

Ticks are widespread in nature and serve as primary vectors for several tick-borne pathogens (TBPs). Ticks and TBPs cause considerable harm to humans and animals and have emerged as a major global public health concern. Domestic dogs are the major reservoirs of zoonotic agents owing to their constant interaction with humans. This study aimed to assess the prevalence and risk factors of canine TBPs, such as Rickettsiales, Coxiella burnetii, hepatozoa, and Borrelia spp., using molecular analyses. A total of 906 dogs were examined and 4 TBPs were identified: Anaplasma phagocytophilum (5; 0.6%), Hepatozoon canis (9; 1.0%), Candidatus Rickettsia longicornii (2; 0.2%), and Rickettsia tamurae (1; 0.1%). Ehrlichia spp., C. burnetii, and Borrelia spp. were not detected. To the best of our knowledge, this is the first study to perform a phylogenetic analysis of Candidatus R. longicornii and R. tamurae in dogs. These findings can help determine the potential public health risks by enhancing our understanding of the geographical and vector distributions of TBPs in Korea.

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 Identification of Borrelia spp. from Ticks in Pastures Nearby Livestock Farms in Korea

Simple Summary

Lyme borreliosis is caused by a spirochete from the Borrelia burgdorferi sensu lato group. Borrelia afzelii and B. garinii are known to be pathogenic to humans. The main vector for Lyme borreliosis is the Ixodes tick. In this study, Borrelia infection was confirmed in Ixodes,Haemaphysalis, and Amblyomma ticks. To our knowledge Borrelia infection was first confirmed in Amblyomma testudinarium in Korea. Based on phylogenetic analysis, all sequences were aligned with B. afzelii isolates and showed a close relationship with high identity. Considering that B. afzelii causes infectious zoonotic diseases, continuous monitoring and attention are still required (although a low prevalence was recorded in this study).

Abstract

Ticks are vectors that spread pathogenic bacteria, viruses, and protozoa. As the number of ticks increases due to climate change, the importance of the study of tick-borne pathogens has also increased. This study was conducted to investigate the distribution of the major tick species causing Lyme borreliosis and regional differences in the prevalence of Borrelia spp. by tick species. Borrelia infection was confirmed not only in Ixodes ticks, which are the major vectors of Borrelia spp., but also in Haemaphysalis and Amblyomma ticks. PCR targeting the 5S-23S rRNA intergenic spacer region (rrf-rrl) was performed to confirm Borrelia positivity. A total of 6102 ticks (736 pools) were tested, and the proportion was Haemaphysalis longicornis nymphs and adults at 69.2%, Haemaphysalis flava nymphs and adults at 13.9%, Haemaphysalis spp. larva at 14.3%, Ixodes nipponensis at 0.8%, and Amblyomma testudinarium at 1.9%. Ixodes nipponensis showed the highest minimum infection rate (MIR: 34.00; 17 pools/50 ticks) for Borrelia spp., followed by A. testudinarium (MIR: 0.88), and H. longicornis (MIR: 0.05). In particular, to our knowledge Borrelia infection was first confirmed in A. testudinarium in Korea. As a result of phylogenetic analysis, all sequences were grouped with Borreliaafzelii isolates and showed a close relationship with high identity. Considering that B. afzelii causes infectious zoonotic diseases, continuous monitoring and attention are needed, although it has a low prevalence in this study.

First report of Borrelia burgdorferi sensu stricto detection in a commune genospecies in Apodemus agrarius in Gwangju, South Korea

Lyme disease is a tick-borne infectious disease caused by the Borrelia burgdorferi sensu lato complex. However, the distribution of Borrelia genospecies and the tissue detection rate of Borrelia in wild rodents have rarely been investigated. Here, we studied 27 wild rodents (Apodemus agrarius) captured in October and November 2016 in Gwangju, South Korea, and performed nested polymerase chain reaction targeting pyrG and ospA to confirm Borrelia infection. Eight rodents (29.6%) tested positive for Borrelia infection. The heart showed the highest infection rate (7/27; 25.9%), followed by the spleen (4/27; 14.8%), kidney (2/27; 7.4%), and lungs (1/27; 3.7%). The B. afzelii infection rate was 25.9%, with the highest rate observed in the heart (7/27; 25.9%), followed by that in the kidney and spleen (both 2/27; 7.4%). B. garinii and B. burgdorferi sensu stricto were detected only in the spleen (1/27; 3.7%). This is the first report of B. burgdorferi sensu stricto infection in wild rodents in South Korea. The rodent hearts showed a high B. afzelii infection rate, whereas the rodent spleens showed high B. garinii and B. burgdorferi sensu stricto infection rates. Besides B. garinii and B. afzelii, B. burgdorferi sensu stricto may cause Lyme disease in South Korea.

Molecular Detection and Phylogenetic Analysis of Tick-Borne Pathogens in Ticks Collected from Horses in the Republic of Korea

The horse industry has grown rapidly as a leisure industry in the Republic of Korea (ROK) in parallel with an increased demand for equestrian activities. As a result, there has been an increase in horse breeding and equestrian population and potential exposure to ticks and their associated pathogens. To provide a better understanding of the potential disease risks of veterinary and medical importance, a study was conducted to determine the geographical distribution and diversity of ticks collected from horses and vegetation associated with horse racetracks/ranches throughout the ROK. This included a survey of five associated common pathogens, Anaplasma phagocytophilum, Ehrlichia chaffeensis, Borrelia spp., Babesia caballi, and Theileria equi. A total 9220 ticks were collected from horses and associated pastures. Ticks were identified to species, stage of development, and sex. Two species of ticks, Haemaphysalis longicornis (99.9%) and Ixodes nipponensis (0.1%) were identified. Two of the target pathogens, A. phagocytophilum and Borrelia spp., were detected in 5/1409 tick pools (0.35%) and 4/1409 pools (0.28%) of H. longicornis, respectively, both of which are zoonotic pathogens of medical importance. The results of 16S rRNA phylogenetic analysis of A. phagocytophilum showed a close relationship to strains distributed in China, USA, Germany, Italy, Turkey, and Poland. Borrelia spp. showed a close relationship, based on 16S rRNA gene, to the strains reported from the USA (B. burgdorferi and B. americana) and Japan (B. tanukii and B. garinii). These results provide information about the potential risks of veterinary and medical importance and the development of mitigation strategies for disease prevention.

Tick-Borne Pathogens in Ticks Collected from Wild Ungulates in North-Eastern Poland

This study was carried out in north-eastern Poland during two hunting seasons between 2018 and 2020. Ticks (Ixodes ricinus and Dermacentor reticulatus) were removed from wild cervids and boars and examined for the presence of Borrelia spirochetes and Rickettsiales members: Rickettsia spp. and Anaplasma phagocytophilum. The present study contributes to the knowledge of even-toed ungulates, which are an important reservoir of the above-mentioned pathogens and a potential source of infections for humans through ticks as vectors. Almost 40% of the collected ticks (191 out of 484) were infected with the following pathogens: 3.3% with Borrelia spp., 19.2% with A. phagocytophilum and 26.9% with Rickettsia spp. Only the ticks collected from cervids carried Borrelia. Typing of the species DNA confirmed the presence of B. afzelii, B. garinii, B. lusitaniae and B. miyamotoi. An analysis of Rickettsia spp. sequences using the GenBank data revealed the presence of R. helvetica, R. raoultii and R. monacensis. Monoinfections (79.1%) dominated over co-infections (20.9%). Among co-infections, the most frequent was A. phagocytophilum/Rickettsia spp. (70%), however co-infections, including B. afzelii/A. phagocytophilum, B. afzelii/Rickettsia spp., B. miyamotoi/A. phagocytophilum and B. afzelii/B. garinii/B. lusitaniae, were also noted. Significant differences were observed in the affinity of some pathogens to their vectors. Thus, Borrelia spp. and A. phagocytophilum were more frequently detected in I. ricinus (5.3% and 23.1%) than in D. reticulatus (1.2% and 15.3%). Infection frequency with Rickettsia spp. was similar (approximately 25–29%) in both tick species. The prevalence of A. phagocytophilum and Rickettsia spp. in ticks removed from cervids was 19.8% and 27.1%, and in ticks from wild boars it was 13.3% and 24.4%, respectively.