Distribution of ticks carrying Severe Fever with Thrombocytopenia Syndrome Virus (SFTSV) around Jiri walking trails of Jeollanam-do, Korea

Abstract

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging disease characterized by fever and thrombocytopenia. Haemaphysalis longicornis ticks comprise the major population of ticks in the environment and have been considered as the main vector for SFTS virus (SFTSV). Here we investigated the distribution of ticks carrying SFTSV collected from the environment using the dragging or sweeping methods during April∼October 2015 in Jeollanam-do, Korea. Sampling was taken from Songjeong, Omi, Bangkwang, Sandong areas in Jiri walking trails. Among the total 3,869 ticks collected, 3,823 ticks (98.8%) were H. longicornis, 41 (1.1%) were Amblyomma testudinarium, and 5 (0.1%) were Ixodes nipponensis. Classification results by regional groups of H. longicornis indicated that 1,613 ticks were collected in Sandong, 1,190 ticks in Omi, 603 ticks in Bangkwang, and 417 ticks in Songjeong. In monthly distributional studies of H. longicornis based on the developmental stages, nymph (325 ticks) was collected from May to October, 94% of larvae from April to June, and 94% of adult from June to August. These results showed the different dominant stage of ticks according to seasons. However, no SFTSV-specific gene was detected in 3,823 ticks of H. longicornis, 41 of A. testudinarium and 5 of I. nipponensis.

Distribution of Tick Vectors of Severe Fever with Thrombocytopenia Syndrome Virus (SFTSV) Collected from Four Environments in Jeju

“…For H. flava, 146 (4.7%) were collected with tick traps and 73 (4.7%) were collected with the flagging method. In other studies, 161 (85%) H. longicornis were collected in Chungju in 2002 and 2003 [11], 158 (95.7%) were collected in Gangwon-do in 2015 [3], and 3,823 (98.8%) were collected in Jeonnam in 2016 [12], showing similar percentage patterns to this survey. It has been confirmed that H. longicornis is distributed widely not only in inland areas, but also in www.kjcls.org all parts of Korea, including Jeju Island.…”

“…As a way to diagnose SFTSV, Yun et al [14] examined the medium segment gene, a specific gene of SFTSV, using RT PCR for H. longicornis in 189 pools, and found 18 positive pools. In a study conducted in Jeollanam-do Province in 2016, SFTSV was not detected in gene analysis using the 2X OneStep RT-PCR method with 127 pooled ticks [12]. In the present study, 3,090 ticks (235 pools) collected using tick traps and 1,569 (129 pools) collected using the flagging method were monitored for SFTSV by RT-PCR.…”

“…Adults were collected regularly from March to November, but were concentrated between May and August, showing a distinct seasonal difference. One report [12] states that ticks were collected in October (325 ticks) from the Dulle-gil of Jirisan Mountain in Jeollanam-do.…”

“…Larvae have been reported to appear in August [11,13]. According to another report [12], nymphs were collected intensively from April to June, and 94% of adults were collected from June to August, showing a distinct seasonal difference. Compared with these previous reports, the results of this survey are not very different.…”