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.