Dabieshan tick virus (DTV, Uukuvirus dabieshanense), has been reported in China and Japan, but its presence and genetic characteristics in the Republic of Korea (ROK) remain poorly understood. This study investigated the occurrence and genetic diversity of DTV in ticks collected from wild animals in Gangwon-do, ROK, between July and September 2022. Among 324 ticks obtained from 29 individuals of eight wildlife species, 15 partial S-segment sequences (632 bp; 4.6%) were detected by nested PCR, including 13 Haemaphysalis (H.) longicornis, one H. flava, and one unidentified Haemaphysalis sp. Phylogenetic and haplotype analyses identified three genetic clusters and seven haplotypes (Hd = 0.867; π = 0.00727), with neutrality tests (Tajima's D and Fu and Li's D*/F*) indicating no evidence of recent population expansion. One genetically divergent sequence detected in H. longicornis from a Northern Goshawk suggests potential host-associated variation. This study bridges a regional data gap by providing the first molecular evidence of DTV circulating in wildlife-associated ticks in the ROK and offers baseline information on its genetic diversity. Continued surveillance of ticks and wildlife hosts will help clarify the distribution and evolutionary dynamics of DTV in the region.

Nanopore sequencing is a powerful tool for real-time pathogen detection and genomic characterization; however, its application to individual ticks is limited by abundant host-derived nucleic acids and low viral RNA levels. In this study, we applied nanopore adaptive sampling (NAS) to sequence viral RNA from individual Haemaphysalis (H.) ticks collected in the Republic of Korea (ROK). By combining NAS with long-read sequencing, high-resolution genome assembly can be achieved from samples containing low-abundance viral RNA and relatively short complementary DNA (cDNA) fragments generated during library preparation. These results indicate that NAS remains effective under suboptimal fragment-size conditions and improves genome assembly compared to conventional nanopore workflows. Phylogenetic analyses revealed that the detected Dabieshan tick virus (DTV) sequences were clustered with isolates from China and Japan, suggesting regional circulation facilitated by the widespread distribution of H. longicornis. Unlike previous studies relying on pooled samples without selective sequencing, NAS allowed high-resolution viral genome assembly from single ticks. These findings confirm the presence and genotypes of DTV for the first time in the ROK and demonstrate NAS as a practical, scalable approach for tick-borne RNA virus surveillance in single ticks, improving genomic assembly and supporting the monitoring of emerging tick-borne viruses in endemic regions.

Severe fever with thrombocytopenia syndrome virus (SFTSV, Bandavirus dabieense) is an emerging tick-borne zoonotic virus causing severe febrile illness with high fatality rates in humans. While ixodid ticks are the primary vectors, secondary transmission through close contact with infected companion animals has also been reported. We describe the clinical characteristics of SFTSV infection in two companion canines from Seoul, Republic of Korea (ROK). Hematological analysis revealed elevated C-reactive protein (CRP) level, increased immature platelet fraction (IPF), leukopenia, and thrombocytopenia. Radiography and abdominal ultrasonography demonstrated splenomegaly, enlarged sublumbar lymph nodes, partial loss of wall layering, and colonic wall thickening; notably, one canine also developed hemorrhagic diarrhea. SFTSV RNA was detected in whole blood by nested PCR, and genotypes were identified as Sub-genotype B-1 and Genotype F. These observations indicate that canine SFTSV infection can manifest with more diverse and severe clinical features than previously recognized. Splenomegaly and colonic abnormalities may serve as useful diagnostic indicators in canine cases. This report emphasizes the importance of considering SFTSV in canines presenting with systemic inflammatory and gastrointestinal signs, and highlights the need for companion animal-based surveillance within a One Health framework. Further studies are warranted to define the full clinical spectrum and to clarify the epidemiological role of canines in SFTS transmission.

Bandavirus dabieense severe fever with thrombocytopenia syndrome virus (SFTSV) is an emerging tick-borne zoonotic virus that causes severe febrile illness and high fatality rates in people. SFTSV is endemic to East Asia, notably in the Republic of Korea (ROK), Japan, and China. Although several studies have reported SFTSV infections in domestic cats (Felis catus), reports of SFTSV in wild felids have been lacking. Previous serological analyses suggest exposure to SFTSV in various wildlife species. However, the clinical outcomes and the role of these animals in SFTSV transmission remain unclear. This study reports the first isolation and whole-genome analysis of SFTSV from a wild leopard cat (Prionailurus bengalensis euptilura) in the ROK. SFTSV was first detected in spleen tissue using real-time PCR, successfully isolated in Vero E6 cells, and confirmed with nested PCR and immunofluorescence assay (IFA). Phylogenetic analysis of whole-genome sequencing, including the L, M, and S segments, revealed that SFTSV from the leopard cat strain, belonging to sub-genotype B-1, showed 99.81%-99.94% nucleotide and 99.65%-99.95% of amino acid identity to previously reported strains from domestic cat and humans in the ROK. Notably, three distinct amino acid mutations, C12Y and H518Q in the M segment and F118S in the S segment, were unique to the leopard cat strain. While no remarkable gross pathological lesions were observed, the absence of other apparent causes of death suggests that SFTSV infection may have contributed. This study provides the first confirmed case of natural SFTSV infection with successful virus isolation from a wild leopard cat in the ROK. Our findings underscore the value of wild felids as ecological indicators of SFTSV circulation across diverse host within tick-borne transmission systems. These results highlight the importance of continued one health based surveillance to better understand the environmental and ecological contexts in which SFTSV persists.

Severe fever with thrombocytopenia syndrome virus (SFTSV) is a tick-borne zoonotic pathogen. We evaluated nanopore adaptive sampling (NAS) for whole-genome assembly using two wildlife-derived SFTSV isolates (Vero cell-cultured) sequenced alongside tick-derived samples. Using the PromethION platform, complete L, M, and S segments were successfully assembled in a single run. NAS supported the reconstruction of previously characterized isolate, including an extended S segment, and enabled the characterization of a genotype B-2 isolate. These results suggest that NAS is an effective tool for genomic surveillance of SFTSV under complex sequencing conditions.

Bandavirus dabieense is the tickborne causative agent of Severe Fever with Thrombocytopenia Syndrome (SFTS), a disease with low incidence but high severity among detected cases and high likelihood of continued geographic spread. To date, evidence of human infections has been reported in eight countries across Asia and in Kenya; surveillance systems in China, the Republic of Korea, and Japan report most cases. Seroprevalence findings in healthy populations have revealed asymptomatic infection and under-ascertainment in endemic areas. In the absence of dedicated therapeutics and vaccines, recommendations for SFTS control focus on prevention of tick bites. However, increasingly, evidence of context-specific transmission pathways that include diverse competent arthropod vectors and non-human mammalian intermediate hosts emphasize that transmission via direct tick bite explains an unknown fraction of infections. Rural populations engaged in agriculture, populations living in transitional zones with frequent tick exposures, and health workers are expected to be at highest risk of infection, while disease burden is greatest in the elderly.Like other viral zoonoses, SFTS has significant and context-specific epidemiological complexity while also being rare, rendering assessment of burden and evaluation of intervention effectiveness challenging. However, its recognition as a global health threat has led to heightened post-pandemic investment in vaccine development. This Vaccine Value Profile (VVP) is intended to overview the current state of evidence on SFTS, present most plausible vaccine use cases in light of the evidence, and highlight persisting uncertainties that require address before full assessment of the potential public health, economic, and societal value of vaccines in the development pipeline can be undertaken. With some adaptation, the VVP has been developed using an existing template by a group of subject matter experts from academia, industry, government, and clinical practice. It has been framed in the context of a One Health approach to control of emerging diseases.

IMPORTANCE:Climate and anthropogenic changes have resulted in the growth of tick populations and tick-borne pathogens worldwide. Standardized surveillance systems are essential for novel tick-borne pathogens in the Republic of Korea (ROK). Analysis of blood-fed ticks suggests that zoonotic pathogens have the potential to circulate between ticks and wild animals in natural environments. OBJECTIVE:This study aimed to analyze blood-fed ticks from wild animals in the ROK and detect novel tick-borne pathogens in the ROK to develop effective surveillance systems and preventive strategies. METHODS:Next-generation sequencing (NGS) identified 217 ticks with eight pooled samples collected from five wild mammals and 22 birds in five wildlife rescue centers and three bird banding stations in the ROK from February 2022 to May 2023. RESULTS:After NGS, clean reads of 17,017,249-32,372,003 viruses, 116,996-289,716 bacteria, and 164,462-352,826 protozoa were obtained in each region. Several pathogens, including those in families such as Phenuiviridae, cause zoonotic diseases. This study identified 39 species, including 30 viruses, eight bacteria, and one protozoan, in 217 blood-feeding ticks from five wild mammals and 22 wild birds. CONCLUSIONS AND RELEVANCE:This study suggests that tick-borne zoonotic pathogens can circulate in ticks and animals and have potential transmission effects in humans. Hence, wild animals, including mammals and birds, may serve as reservoirs of zoonotic infection carriers.

Background: The zoonotic infectious disease, severe fever with thrombocytopenia syndrome (SFTS), caused by the SFTS virus (SFTSV), Bandavirus dabieense, was first identified in China in 2009 and reported in the Republic of Korea in 2013. The primary vector is the tick Haemaphysalis (H.) longicornis, which is endemic to the Asia-Pacific region and has a wide range of hosts. While SFTSV has been studied in various wildlife species, no investigation has focused explicitly on bats, which are ecologically significant in the transmission of zoonotic viruses. Materials and Methods: To investigate the relationship between bats and SFTSV, 1,200 ticks were collected from 12 sites in 6 provinces within 1 km of bat habitats using flagging, and 147 bat sera were collected via cardiac puncture after ether anesthesia between November 2021 and September 2022. Total RNA was extracted from the ticks and bat sera, and nested reverse transcription polymerase chain reaction was performed to amplify the S segment of SFTSV. Bat sera were analyzed for IgG antibodies against SFTSV by enzyme-linked immunosorbent assay (ELISA). Results: Within 1 km of bat habitats, 881 H. longicornis, 209 H. flava, 96 Haemaphysalis spp., and 14 Ixodes (I.) nipponensis were identified. SFTSV was detected in 12.3% (147/1,200) of the ticks. Although no SFTSV RNA was detected in bat sera by nested PCR, 3.4% (5/147) were seropositive by ELISA. Conclusion: While molecular evidence of SFTSV infection was not observed in bats, a few serological positives suggest possible past exposure. The detection of SFTSV in ticks collected from bat habitats suggests potential ecological interactions involving bats, ticks, and other wildlife species. These findings highlight the importance of considering both wildlife reservoirs and the indirect role of bats in the geographical spread of SFTSV.

Calf diarrhea remains a significant concern in the global cattle industry, leading to considerable economic losses. Infectious pathogens are among the primary causes of this disease. In this study, the prevalence of 7 pathogens—bovine rotavirus (BRV), bovine coronavirus (BCV), bovine viral diarrhea virus (BVDV) types 1 and 2, Cryptosporidium parvum, Giardia spp., and Eimeria spp.—associated with calf diarrhea was investigated using polymerase chain reaction (PCR). A metagenomic approach was also applied to identify additional RNA viral pathogens from unknown causes of diarrheic fecal samples in the Republic of Korea (ROK). A total of 810 fecal samples from Hanwoo calves (Bos taurus coreanae) were collected, consisting of 526 normal samples (267 with a fecal score of 0 and 259 with a fecal score of 1) and 284 diarrheic samples (178 with a fecal score of 2 and 106 with a fecal score of 3). All 7 pathogens were detected by PCR in feces and their detection rates and mean fecal scores for each were as follows: BRV (14.0

Climate and anthropogenic changes have resulted in the growth of tick populations and tick-borne pathogens worldwide. Standardized surveillance systems are essential for novel tick-borne pathogens in the Republic of Korea (ROK). Analysis of blood-fed ticks suggests that zoonotic pathogens have the potential to circulate between ticks and wild animals in natural environments. This study aimed to analyze blood-fed ticks from wild animals in the ROK and detect novel tick-borne pathogens in the ROK to develop effective surveillance systems and preventive strategies. Next-generation sequencing (NGS) identified 217 ticks with eight pooled samples collected from five wild mammals and 22 birds in five wildlife rescue centers and three bird banding stations in the ROK from February 2022 to May 2023. After NGS, clean reads of 17,017,249-32,372,003 viruses, 116,996-289,716 bacteria, and 164,462-352,826 protozoa were obtained in each region. Several pathogens, including those in families such as Phenuiviridae, cause zoonotic diseases. This study identified 39 species, including 30 viruses, eight bacteria, and one protozoan, in 217 blood-feeding ticks from five wild mammals and 22 wild birds. This study suggests that tick-borne zoonotic pathogens can circulate in ticks and animals and have potential transmission effects in humans. Hence, wild animals, including mammals and birds, may serve as reservoirs of zoonotic infection carriers.

ABSTRACT Climate change, land development, and increased outdoor human activity have increased the prevalence and distribution of tick-borne pathogens, causing public health issues. Asia is a pivotal region of emerging infectious diseases caused by zoonotic disease. Therefore, this study aimed to construct effective surveillance systems and establish preventive strategies against novel tick-borne diseases. Next-generation sequencing (NGS) was performed to detect tick-borne pathogens from animal blood-fed ticks. Ticks (n = 261) were collected from different animals across nine Asian countries between 2022 and 2023. Five genera of adults and nymphal ticks were used, namely, Amblyomma, Haemaphysalis, Hyalomma, Rhipicephalus, and Ixodes. The animals from which the ticks were collected were wild, domestic animals, birds, and reptiles, living in the natural environment. After NGS, clean reads of 18,382,262–30,460,619 DNA viruses, 22,744,384–32,400,471 RNA viruses, 134,506–286,282 16S rRNA of bacteria, and 147,154–352,826 18S rRNA of protozoa were obtained from nine Asian countries. After analysis of the species, 28 RNA, 13 DNA viruses, 16 bacteria, and 4 protozoa were detected. Several tick-borne pathogens, including those in families that cause zoonotic diseases, such as Phenuiviridae, Nairoviridae, Rickettsiaceae, and Borreliaceae, were identified. This study is distinctive in that it involved cooperative studies with nine Asian countries to prevent the spread of tick-borne diseases. The results suggest that pathogens, which were detected in animal blood-fed ticks, can circulate in animals and may be transmitted to humans. In addition, this study can provide a basis for effective surveillance systems to prevent novel pathogens.IMPORTANCESurveillance systems against novel tick-borne diseases are significant for global health. Climate and other environmental changes have contributed to an expanding range of ticks and tick-borne diseases. Areas in Asia constitute key areas of emerging infectious diseases. Through analysis of blood-fed ticks, collected from various animals living in the natural environment, we suggest that tick-borne pathogens may harbor animals and environment and have potential risk of transmission in humans. Understanding the distribution of tick-borne pathogens requires cooperative studying and, thus, can construct standardized surveillance systems.

Severe fever with thrombocytopenia syndrome (SFTS) is a life-threatening viral zoonosis. The causative agent of this disease is the Dabie bandavirus, which is usually known as the SFTS virus (SFTSV). Although the role of vertebrates in SFTSV transmission to humans remains uncertain, some reports have suggested that dogs could potentially transmit SFTSV to humans. Consequently, preventive measures against SFTSV in dogs are urgently needed. In the present study, dogs were immunized three times at two-week intervals with formaldehyde-inactivated SFTSV with two types of adjuvants. SFTSV (KCD46) was injected into all dogs two weeks after the final immunization. Control dogs showed viremia from 2 to 4 days post infection (dpi), and displayed white pulp atrophy in the spleen, along with a high level of terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling assay (TUNEL) positive area. However, the inactivated SFTSV vaccine groups exhibited rare pathological changes and significantly reduced TUNEL positive areas in the spleen. Furthermore, SFTSV viral loads were not detected at any of the tested dpi. Our results indicate that both adjuvants can be safely used in combination with an inactivated SFTSV formulation to induce strong neutralizing antibodies. Inactivated SFTSV vaccines effectively prevent pathogenicity and viremia in dogs infected with SFTSV. In conclusion, our study highlighted the potential of inactivated SFTSV vaccination for SFTSV control in dogs.

Changes in elimination behavior, including urination and defecation, are common clinical signs of numerous disorders in cats.Therefore, this study attempted to automatically measure the elimination behavior of cats using the litter box and develop an early warning system for the guardian in case of abnormalities.To construct an early warning system for abnormal changes through cat elimination behavior, it consisted of a litter box, an automatic sensor for data collection and data wifi transmission, a server for data analysis, and a mobile phone app for result transmission and early warning.To establish the reference interval (RI), the elimination behavior was monitored for more than 2 weeks using a motion sensor within a litter box in 37 healthy cats and 19 diseased cats.The data were expressed as daily total visits, daily total stay duration, average stay duration per elimination, weekly total visits, and weekly total stay duration.Healthy cats showed median daily total visits of 3 times/day (RI 1.0-7.0)and daily total stay duration of 192 s/day (RI 8.0-452.0).For weekly data, the median total visits were 20 times/week ) and the median total stay duration was 1,147 s/week (RI 80.0-2,249.5).The average stay duration per elimination was 59 s/elimination (RI 4.67-132.0).Diseased cats showed more frequent elimination behavior than healthy cats (p < 0.001).Otherwise, for each elimination, diseased cats had shorter stay durations than healthy cats (p < 0.001).This study established the RIs of elimination behavior parameters (frequency and duration) in healthy cats.The present study might help guardians and veterinarians detect changes in elimination behaviors in diseased cats at an early stage.

Importance: Despite advancements in herd management, feeding, and pharmaceutical interventions, neonatal calf diarrhea (NCD) remains a major global health concern. Bacteria, viruses, and parasites are the major contributors to NCD. Although several pathogens have been identified in the Republic of Korea (ROK), the etiological agents of numerous NCD cases have not been identified. Objectives: To identify, for the first time, the prevalence and impact of Boosepivirus (BooV) on calf diarrhea in the ROK. Methods: Here, the unknown cause of calf diarrhea was determined using metagenomics We then explored the prevalence of certain pathogens, including BooV, that cause NCD. Seventy diarrheal fecal samples from Hanwoo ( Bos taurus coreanae ) calves were analyzed using reverse transcriptase and quantitative real-time polymerase chain reaction for pathogen detection and BooV isolate sequencing. Results: The complete genome of BooV was detected from unknown causes of calf diarrhea. And also, BooV was the most frequently detected pathogen (35.7%) among 8 pathogens in 70 diarrheic feces from Hanwoo calves. Co-infection analyses indicated that most BooV-positive samples were solely infected with BooV, indicating its significance in NCD in the ROK. All isolates were classified as BooV B in phylogenetic analysis. Conclusions and Relevance: This is the first study to determine the prevalence and molecular characteristics of BooV in calf diarrhea in the ROK, highlighting the potential importance of BooV as a causative agent of calf diarrhea and highlighting the need for further research on its epidemiology and pathogenicity.

Habitat loss of wildlife and increased human activities in their habitat provide more opportunities for human-wild animal contact. These artificial environments influence humans by facilitating the transmission of tick-borne pathogens. Therefore, we aimed to detect and understand circulating tick-borne pathogens in the natural environment by analyzing blood and spleen samples of wild animals admitted to wildlife rescue centers in the Republic of Korea. In total, 376 samples were collected from 355 rescued wild animals immediately after their arrival or death. After DNA deoxyribonucleic acid and RNA extractions, reverse transcription polymerase chain reaction (RT-PCR) and nested PCR were conducted to detect target tick-borne pathogens. This study detected six positive samples of severe fever with thrombocytopenia syndrome virus (SFTSV), 146 Anaplasma phagocytophilum, 55 Anaplasma bovis, 19 Rickettsia spp., 45 Borrelia theileri, and 4 Bartonella schoenbuchensis. Among the positive samples, SFTSV was detected in one spleen sample from a Korean water deer, from which SFTSV was successfully isolated. After full genome sequencing, the L, M, and S segments all belonged to genotype B-3 and indicated 99.84 % ∼ 99.94 % similarity with SFTSV isolated from human serum. In conclusion, wild animals are potential reservoirs of tick-borne pathogens. Therefore, surveillance systems to prevent transmission among ticks, animals, and humans must be developed using the One Health concept.

Background: Severe fever with thrombocytopenia syndrome (SFTS) is an emerging tick-borne disease caused by Bandavirus dabieense. Initially identified in China, this disease has spread throughout Asian countries via tick bites and animal-to-human transmission. However, reports of the prevalence of SFTS virus (SFTSV) in cattle in Korea are lacking. This study aimed to investigate SFTSV infections in grazing cattle in the Republic of Korea (ROK). Materials and Methods: In total, 845 grazing cattle serum samples were collected over 2 years (2019 and 2020) in the ROK, and viral RNA was extracted using a kit. One-step RT-nested PCR was performed to amplify the S-segment of SFTSV. Positive serum samples were used to isolate SFTSV in Vero E6 cells, and the full sequences were analyzed. A phylogenetic tree was constructed using the maximum-likelihood method with MEGA X. In addition, immunoglobulin G antibodies against SFTSV were investigated using an enzyme-linked immunosorbent assay. Results: Here, 4.0% of serum samples (34/845) were positive for SFTSV S-segments, and one virus isolate was cultured in Vero E6 cells. Phylogenetic analysis based on the partial S-segment classified 4 SFTSV isolates as the B-2 genotype, 9 as the B-3 genotype, 18 as an unclassified B genotype, and 3 as the D genotype. One cultured virus was classified as the B-2 genotype based on SFTSV L-, M-, and S-segments. Antibody detection results showed that 21.1% of serum samples (161/763) were positive for SFTSV. Conclusion: To the best of our knowledge, this is the first study performed to identify the prevalence of SFTSV in grazing cattle in the ROK. Our findings indicate the necessity for more intensive and continuous SFTSV monitoring, not only in cattle but also in other animals, to comprehend the genetic diversity of the virus and its potential eco-epidemiological impact on human health.

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.

The causative agent of severe fever with thrombocytopenia syndrome (SFTS) is Bandavirus dabieense, an emerging tick-borne zoonotic pathogen. Migratory birds have often been suggested as potential carriers of ticks that can transmit Bandavirus dabieense; however, their role remains unclear. The Republic of Korea (ROK) holds an important position as a stopover on the East Asian-Australasian Flyway. The present study aimed to investigate the potential involvement of migratory birds in the transmission of the SFTS virus (SFTSV) in the ROK. A total of 4,497 ticks were collected across various regions, including Heuksando and Daecheongdo, in the ROK, from bird migration seasons in 2022 and 2023. Genetic analysis of the SFTSV was performed for 96 ticks collected from 20 different species of migratory birds. Polymerase chain reaction (PCR) fragments of SFTSV were detected in one Haemaphysalis concinna nymph collected from a Black-faced Bunting (Emberiza spodocephala) and one Ixodes turdus nymph collected from an Olive-backed Pipit (Anthus hodgsoni) on Daecheongdo and Heuksando, respectively, during their northward migration in two spring seasons. This finding suggests that migratory birds can be considered as possible carriers and long-distance dispersers of ticks and associated tick-borne diseases. This study highlights the importance of clarifying the role and impact of migratory birds in the rapid expansion of tick-borne diseases, facilitating enhanced preparedness and the development of mitigation measures against emerging SFTS across and beyond East Asia.

Background: Severe fever with thrombocytopenia syndrome (SFTS) is an emerging zoonotic tick-borne disease in East Asia caused by the SFTS virus (SFTSV). It is to investigate the presence of SFTSV RNA and antibodies in horses from a slaughterhouse and equestrian centers in the Republic of Korea (ROK). A prevalence study of SFTSV-specific RNA and antibodies was designed from 889 horses in the ROK. Materials and Methods: Serum samples were collected from horses at a slaughterhouse and equestrian centers from 2018 to 2020. To detect the presence of SFTSV, RNA was extracted from the serum samples, and a nested reverse transcription-polymerase chain reaction (RT-PCR) was conducted. Sequencing data were analyzed, and a phylogenetic tree was constructed using the maximum-likelihood method with Molecular Evolutionary Genetics Analysis Version 7.0 software. The horse sera were also tested for SFTSV-specific immunoglobulin G antibodies using enzyme-linked immunosorbent assay (ELISA). Results: Twelve of 889 (1.3%) horse sera were positive for SFTSV RNA, and 452 of 887 (51.0%) horse sera were seropositive by ELISA. Among the RT-PCR-positive samples, 12 of the SFTSV S-segment sequences were classified as sub-genotypes B-2 (n = 6) and B-3 (n = 6). ELISA analysis was evaluated by comparison with neutralization test. We investigated SFTSV infection in horses over a 3-year period, but sampling was not performed evenly by season; continuous surveillance of SFTSV in horses is needed. Conclusions: We report the detection of SFTSV RNA and provide serological data on SFTSV prevalence in horses in the ROK. The detection of SFTSV-specific RNA and antibodies in horses, which are in close proximity to humans, suggests that SFTS is an emerging and important health issue, indicating that more attention to its relevance for equestrian workers is needed.