Heamaphysalis longicornis is a major vector for Severe Fever with Thrombocytopenia Syndrome (SFTS) virus and the density of the vector has been increasing because of the climate change. The incidence of fatalities due to SFTS is increasing every year. In this study, to evaluate the SFTS transmission by ticks, the density of ticks mediating SFTS was monitored. Tick was collected every month from four different sites (Grass land, Mountain path, Grave, Copse) in Andong with the traps containing dry ice as CO2 attractants. Among 2,572 ticks of 3 species; H. longicornis, H. flava, and Ixodes nipponensis were most abundantly collected from April to August. H. longicornis is the richest species (92.8%), whereas Ixodes nipponensis was the least species (0.8%). The 54.5% of the sample were nymph stage and female/male ratio was 64.3%. According to the pathogene analysis, SFTS virus was detected from H. longicornis adult and larvae stages collected in July and August. In July samples, SFTS virus was detected only from grassland site, but the virus was observed in the sample from all four sites in August. For effective prevention of SFTS, the tick density should be continuously monitored based on the onset time of SFTS with the consideration of habitate, habit & life history of ticks.

Seasonal distribution of disease vector species including mosquitoes and ticks plays a key role in establishing risk managementof vector-borne disease. However, environmental factors affecting abundance and distribution of vector species are notcurrently well understood. Therefore, we conducted a two-year field sampling to address the population dynamics of mosquitoesand ticks in Gyeonggi-do in 2015 and 2016. In 2015, the population density was highest in May for ticks (e.g. Haemaphysalislongicornis) and June for mosquitoes (e.g. Aedes vexans), whereas both pest groups peaked in August in 2016. Culexpipens (82.3% Species Ratio), Ae. vexans (77.3% SR), and Anopheles sinesis sp. (45.3% SR) were the most dominantspecies in urban area, cow shed and wild bird refuge, respectively. For ticks, H. longicornis (47.7% SR) was the mostdominant throughout four potential habitats.

The purpose of this monitoring is to survey the geographical distribution of tick species using dry ice bait traps and flagging methods at each ten provinces (GangwonⅠ,GangwonⅡ, Gyeonggi, Chungbuk, Chungnam, Gyeongbuk, Gyeongnam, Jeonbuk, Jeonnam and Jeju area) and one Metropolitan area in the Republic of Korea for eight months from April through November, 2016. A total of 65,339 ixodid ticks (8,200 females, 1,988 males, 31,453 nymphs and 23,698 larvae) was collected, belonging to three genera (Haemaphysalis, Ixodes and Amblyomma). Haemaphysalis longicornis was the most commonly collected species, which is represented for 96.88% of all the collected ticks and followed by H. flava (2.69%), I. nipponensis (0.35%), A. testudinarium (0.05%) and H. japonica (0.03%) in the Republic of Korea for the study period. Haemaphysalis longicornis was a dominant species observed in these eleven areas.

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging tick-borne zoonosis and SFTS virus is transmitted to humans by tick bites. The aim of this study was to monitor tick population and its SFTS virus infection. During March 2014 to October 2015, ticks were monthly sampled using dry-ice bait trap and flag method from 4 collecting points in Boeun-gun. A total of 16,500 ticks, including 14,646 Haemaphysalis longicornis (88.7%), 1,825 H. flava (11.1%), and 29 Ixodes nipponensis (0.2%), were collected. Ticks were pooled (5,156 ticks in 456 pools) and tested by RT-PCR and nested PCR and the minimum infection rate of ticks was 0.27% (14 pools) consisting of 0.13% H. longicornis (6 pools), 1.19% H. flava (8 pools). This annual surveillance study will be needed for long-term monitoring of ixodid ticks in Korea.

The geographical distribution of ixodid ticks in were surveyed at 10 areas from April to November 2015. We investigated tick distribution using dry ice bait trap and flagging method as a part of disease vector monitoring in Korea. As a result, ticks collected 29,992 ixodid ticks with 3 genera, 7 species. Among them, Genus Haemaphysalis, Ixodes and Amblyomma accounted for 29,751 (99.2%), 223 (0.7%) and 18 (0.1%). Haemaphysalis longicornis was accounted for 88.9%, which has become the dominant species. Some species, such as H. japonica and Ixodes persulcatus were only collected Gangwon area. Metropolitan area had the highest population of ticks 6,540 (21.8%), Chungbuk area was next 5,049 (16.8%). In environmental distribution, Genus Haemaphysalis was highly collected in grassland site (32.1%) and Genus Ixodes was highly collected in coniferous forest site (43.5%). Upon analysis of the monthly distribution, H. longicornis, the dominant species, was highly collected at nymph stage in May, and its larva was highly collected in September. These studies may provide important information for control and management of tick in Korea.

We investigated the distribution of ixodid ticks in severe fever with thrombocytopenia syndrome (SFTS) case reported areas using flagging method from May to November 2014 in Korea. We collected 13,471 ixodid ticks with 2 genera and 3 species. Among them, Genus Haemaphysalis and Ixodes accounted for 99.9% (13,455) and 0.1% (16), respectively. Genus Haemaphysalis consisted of 2 species, H. longicornis (96.2%) and H. flava (3.7%). I. nipponensis was only collected in Genus Ixodes. H. longicornis was the dominant species (over 90%) in most study areas. Ixodid ticks were evenly distributed at various environmental sites, such as residences, hills, grassfields, fields, graves, copses, other sites. The further study on SFTSV infection in ixodid ticks will be needed.

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging disease, causing high fever, thromobocytopenia, leukopenia, gastrointestinal simptoms (vomiting, diarrhea), hemorrhage and multiorgan dysfunction. It was known that Haemaphysalis longicornis (H. longicornis), a major tick in Korea, is the principal vector for severe fever with thrombocytopenia syndrome virus (SFTSV). Firstly, to investigate the existence and prevalence of SFTSV in the country, we collected the ticks in 9 provinces in South Korea and detected SFTSV from H. longicornis ticks from 2011 to 2012. And we also investigated SFTSV infection in ticks collected from healthy humans without SFTS symptom and their residential areas. From the former study, we collected 13,053 ticks, and H. longicornis (90.8%, 11,856/13,053) was the most abundant among them. The minimum infection rate (MIR) of SFTSV in H. longicornis was 0.5% (59 pools). From the later study, totally 422 ticks of 8 species were collected from humans and at their neighborhood throughout the nation from May to October, 2013 and SFTSVs were detected from 12 pools (5.7% MIR) by RT-PCR. Finally, we diagnosed 35 patients by detecting SFTSV gene with their sera, and isolated 26 SFTSVs among them in 2013. These findings indicate that SFTSVs are prevalent and SFTS is probably endemic in Korea.

Haemaphysalis longicornis (Hl) as members of the ixodid tick inhabits lots of grass thicket of field and mountain. Ticks are blood-feeding ectoparasites that can mediate a variety of diseases to human and animals, causing Lyme disease, Rocky Mountain spotted fever, and human monocytic ehrlichiosis. Particularly, ticks can trigger an inflammatory response representing symptoms about swelling and itching in human. The aim of this study is to investigate the effect of H. longicornis extract (HlE) on production of inflammatory cytokines and their mRNA in human monocytic THP-1 cells. In a time- and dose-dependent manner, human monocytic THP-1 cells was treated with HlE. Supernatants were analyzed for the production of cytokines using enzyme-linked immunosorbent assay (ELISA). mRNA level in the culture cells was measured by a reverse transcriptase-polymerase chain reaction (RT-PCR). As a result of this study, HlE significantly induced secretion of IL-6, IL-8, and MCP-1 in THP-1 cells. These results suggest that HlE increase the release of proteins and mRNAs level of inflammatory cytokines in THP-1 cells. HlE may play a role in contributing to inflammatory diseases through stimulation of immune cells. Further research of H. longicornis is needed to better understand the elucidation of the pathogenic mechanism.

We investigated the prevalence of severe fever with thrombocytopenia- syndrome virus (SFTSV) and geographical distribution of ixodid ticks from 25 regions of the Korea during 2011-2012. We collected 25,940 ixodid ticks with 3 genera and 7 species using dry ice bait trap and flagging. Among them, Genus Haemaphysalis, Ixodes and Amblyomma counted 25,821 (99.5%), 118 (0.5%) and 1 (<0.0%). Genus Haemaphysalis consisted of 4 species, H. longicornis (90.4%), H. flava (9.2%), H. formosensis and H. hystricis (<0.1%). Genus Ixodes consisted of 2 species, I. nippoenesis (0.4%) and I. persulcatus (0.1%). Only one Amblyomma testudinarium was collected. The highly infested sites were grassland (50.1%) and mixed stand forest (20.3%). Minimum infection rate (MIR) of SFTSV in H. longicornis was 0.5% in Korea and this rate was similar to that in China (0.46%). Our results showed that H. longicornis is a major vector of SFTSV and its surveillance will be needed at high risk area.

Borrelia, which is transmitted by arthropod, is known as an infectious agent to vertebrate, such as Lyme disease (LD) Borrelia and Relapsing fever (RF) Borrelia. LD Borrelia is only transmitted by hard-bodied ticks classified into the Ixodes ticks. In contrast, almost of RF Borrelia was transmitted by soft-bodied ticks, Argasid ticks. Thus so far, the co-evolution was thought to be established between Borrelia and tick. In this study, we found unknown borreliae from imported reptiles and its associated ticks (we preliminary named as ‘REP Borrelia’). Ticks were introduced into Japan with world-wide trading of reptiles. Ticks were classified into genus Amblyomma or Hyalomma. Out of 82 ticks, 76 were positive for PCR of tickmitochondrial gene for 16S rRNA, and we used these 76 ticks for our examination. From 57 ticks (75%), Borrelia turcica and unknown three Borrelia spp. were detected or isolated. In addition, we examined imported reptiles which were infested exotic ticks. A total of 15 reptiles including 5 of Testudo graeca, 1 of T. horsfieldii, 2 of Phelsuma dubia and 7 of Geochelone pardalis were used for isolation study of Borrelia. Borrelia was isolated from 11 reptiles (73.3%) as follows: T. graeca, T. horsfieldii, G. pardalis. It suggested that, these imported reptiles and exotic ticks were highly infected with Borrelia. Phylogenetic analysis based on the DNA sequences of Borrelia, it was indicated that REP Borrelia constituted a cluster which was independent from RF and LD Borrelia. Surprisingly, this REP Borrelia was expected that was transmitted by hard-bodied tick, although it was thought to be diverged from ancestor RF Borrelia. From quantitative analysis of divergence based on 16S rRNA gene, it was expected that REP and RF Borrelia were differentiated around 50 million years ago (MYA). On the other hand, the oldest soft-bodied tick fossil from New Jersey amber was indicated that soft-bodied tick was speciated since ~92 MYA. In fact, soft-bodied tick was already diverged into genus level when RF and REP Borrelia were diverged. This may suggest that the vector switching event was occurred in ancestor REP/RF Borrelia.