Severe Fever with Thrombocytopenia Syndrome Virus in Ticks in the Republic of Korea.

Severe fever with thrombocytopenia syndrome virus (SFTSV) is a zoonotic, tick-borne RNA virus of the genus Bandavirus (Family Phenuiviridae), mainly reported in China, Japan, and the Republic of Korea (Korea). For the purpose of this study, a total of 3,898 adult and nymphal ticks of species Haemaphysalis longicornis (94.2%), Haemaphysalis flava (5.0%), Ixodes nipponensis (0.8%), and 1 specimen of Ixodes ovatus, were collected from the Deogyusan National Park, Korea, between April 2016 and June 2018. A single-step reverse transcriptase-nested PCR was performed, targeting the S segment of the SFTSV RNA. Total infection rate (IR) of SFTSV in individual ticks was found to be 6.0%. Based on developmental stages, IR was 5.3% in adults and 6.0% in nymphs. The S segment sequences obtained from PCR were divided into 17 haplotypes. All haplotypes were phylogenetically clustered into clades B-2 and B-3, with 92.7% sequences in B-2 and 7.3% in B-3. These observations indicate that the Korean SFTSV strains were closer to the Japanese than the Chinese strains. Further epidemiological studies are necessary to better understand the characteristics of the Korean SFTSV and its transmission cycle in the ecosystem.

First detection of Borrelia and Rickettsia species from Ornithodoros ticks in the Republic of Korea.

Ticks are considered important vectors among arthropods and are linked to serious medical and veterinary health problems. In this study, we investigated tick-borne pathogens (TBPs) of Ornithodoros (Carios) sawaii and a newly identified Ornithodoros species from migratory bird nests in the uninhabited islands of the Republic of Korea (ROK). Ticks were collected from seabird nests with soil using a Tullgren funnel. Polymerase chain reaction (PCR) was performed using specific primer sets targeting genes of Borrelia spp., Rickettsia sp., Anaplasma phagocytophilum, Anaplasma bovis, and Bartonella spp. for molecular identification of TBPs, and two pathogens, Borrelia sp. and Rickettsia sp. were detected via PCR. Sequence data were analyzed and a phylogenetic analysis was conducted using the maximum-likelihood method in MEGA v.7. The detection rate of Borrelia sp. in O.(C.) sawaii was 6.8 % (5/74), and that of Rickettsia sp. in O. sawaii and the newly identified Ornithodoros species. was 36.5 % (27/74). Sequencing analysis revealed that the 16S ribosomal (r) RNA and flagellin genes of Borrelia sp., and the citrate synthase (gltA) and 17-kDa antigen gene of Rickettsia sp. were closely phylogenetically related to those of Borrelia turicatae and Rickettsia asembonensis. This is the first report identifying Borrelia sp. and Rickettsia sp. from O. sawaii, and Rickettsia sp. from the newly identified Ornithodoros species in the ROK, and these results imply that soft ticks (O. sawaii, and the newly identified Ornithodoros species) may function as pathogen carriers with important implications for public health throughout their distribution areas in Asia.

First report of Newly Identified Ornithodoros Species in the Republic of Korea.

Ticks and tick-borne diseases are important issues worldwide because of their effects on animal and human health. The genus Ornithodoros, which is included in the family Argasidae, is typically associated with wild animals, including seabirds. In this study, samples from the nests of seabirds and surrounding soil were collected to investigate Ornithodoros spp. from 9 uninhabited islands in the western, eastern, and southern parts of Korea from April 2017 to October 2018. The islands are known as the breeding places of migratory and resident birds. Ticks were collected from soil and nest material of seabirds using a Tullgren funnel and identified using 16S rRNA and the cytochrome c oxidase 1 gene (COI), and host animals of soft ticks were identified using the mitochondrial DNA cytochrome b gene by a polymerase chain reaction. In the sequence identity of the 16S rRNA gene fragment of Ornithodoros sp., Ornithodoros sawaii was identified as the closest homologous sequence, and the new Ornithodoros sp. was newly identified. We found that the newly identified Ornithodoros sp. in the Republic of Korea was located in uninhabited islands used as breeding places by the black-tailed gull, Larus crassirostris.

Severe Fever with Thrombocytopenia Syndrome Virus in Dogs, South Korea.

Of 103 serum samples collected from dogs in South Korea, 3 (2.9%) were positive for severe fever with thrombocytopenia syndrome virus (SFTSV) and 22 (21.4%) were positive for antibodies against SFTSV. A dog-derived isolate of SFTSV clustered with many South Korea SFTSV strains in the Japanese clade.

Prevalence of Severe Fever with Thrombocytopenia Syndrome Virus in Ticks Collected from National Parks in Korea.

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging viral disease in East Asian countries, including China, Japan, and the Republic of Korea (ROK). The causative agent of SFTS is the SFTS virus (SFTSV), which is transmitted by ticks. To investigate the prevalence of SFTSV in the ROK, a total of 9744 ticks were collected from vegetation in five national parks between July and November 2015. Of the collected adult and nymph ticks, Haemaphysalis longicornis (68.44%) was the most abundant, followed by Haemaphysalis flava (29.66%), Ixodes nipponensis (1.56%), and Amblyomma testudinarium (0.34%). Collected larval ticks were of the genera Haemaphysalis (99.61%) and Ixodes (0.39%). One-step RT-PCR and nested PCR were used to detect SFTSV-specific genes from each individual adult and nymph tick and pooled larval ticks. SFTSV was detected in 4.77% (48/1006) in H. longicornis, 1.15% (5/436) in H. flava, 0% (0/23) in I. nipponensis, and 20% (1/5) in A. testudinarium. The infection rate of SFTSV in adult and nymph ticks was 3.61%. The prevalence of SFTSV in adult and nymph ticks was relatively high, compared with previous reports. In larval ticks, the minimum infection rate was 0.31%. SFTSV was detected in ticks collected from both trail and nontrail areas in the national parks, and up to 800 meters above sea level. The sequences obtained showed 99.4-99.7% homology with SFTS virus S segment sequences from Chinese and Japanese ticks.

Molecular Detection of Severe Fever with Thrombocytopenia Syndrome Virus in Korean Domesticated Pigs.

BACKGROUND: Severe fever with thrombocytopenia syndrome virus (SFTSV) is an emerging tick-borne virus in China, Japan, and Korea. Although the incidence of SFTS has been increasing annually since the first SFTSV case was reported in Korea, the prevalence of SFTSV in Korean livestock has not conducted. The purpose of this study was to investigate the prevalence of SFTSV in domesticated pigs (Sus scrofa domesticus) throughout Korea. METHODS: A total of 240 sera were collected from 30 domesticated pigs in eight provinces. To detect SFTSV, one-step reverse transcription RT nested PCR was conducted using SFTSV genome-specific primer sets. The amplified PCR products were cloned and then sequenced. RESULTS: Four of 240 (1.7%) pig sera tested positive for SFTSV through one-step RT nested PCR. Two of the four obtained sequences were included in the Japanese clade, whereas the other two sequences were related to the Chinese clade based on phylogenetic analysis. Moreover, the obtained SFTSV sequences from this study were distinct from human SFTSV strains. CONCLUSIONS: This study is the first to attempt the identification of SFTSV sequences from domesticated pigs and the first molecular detection of SFTSV in Korean livestock. Our findings indicate that a new subclade of SFTSV-different from that in humans-may be present in domesticated pigs; the surveillance of SFTSV in livestock is required to better understand the life cycle of SFTSV.

Molecular Detection of Anaplasma, Bartonella, and Borrelia theileri in Raccoon Dogs (Nyctereutes procyonoides) in Korea.

Anaplasmosis, cat-scratch disease, and Lyme disease are emerging vector-borne infectious diseases in Korea. Although the prevalence of vector-borne pathogens (VBPs) in domestic animals and vector arthropods has been documented, there is limited information on the presence of VBPs in wild animals. The raccoon dog (Nyctereutes procyonoides), a wild canid found in East Asia and Europe, represents a potential wildlife reservoir for zoonotic diseases. To investigate the prevalence of VBPs in raccoon dogs, 142 carcasses and 51 blood samples from captured raccoon dogs were collected from 2003 to 2010 and from 2008 to 2009, respectively, in Korea. In addition, 105 Haemaphysalis flava (14 larvae, 43 nymphs, 32 males, and 16 females) and nine Haemaphysalis longicornis (all female) were collected from three raccoon dogs. Samples of the spleen and blood were tested for the presence of VBPs by using nested polymerase chain reaction. Among the samples collected from 193 raccoon dogs and 114 ticks, two samples were positive for Anaplasma phagocytophilum, four for Anaplasma bovis, two for Borrelia theileri, and two for Bartonella henselae. To the best of our knowledge, this study is the largest survey of raccoon dogs aimed at the analysis of VBPs in this species. Moreover, the present study represents the first identification of A. phagocytophilum, B. henselae, and B. theileri in raccoon dogs in their native habitat (East Asia).