Epidemiology of Severe Fever with Thrombocytopenia Syndrome Virus in South Korea
Jeong Rae Yoo1, Sang Taek Heo1, Yu Mi Wi2 and Keun Hwa Lee1*
1Jeju National University College of Medicine, Jeju, South Korea and 2Sungkyunkwan University, Changwon-si, South Korea
Severe fever with thrombocytopenia syndrome (SFTS) is a tick-borne viral disease with a high mortality rate and infection can also occur through close contact with an infected patient such as Crimean-Congo hemorrhagic fever (CCHF).
SFTS was first suspected in China in 2009, the causative virus was reported in 2011 and SFTSV expanded from China to South Korea and Japan in 2012-2013. Most SFTSV infections occur through Haemaphysalis longicornis, which acts as a transmission host between animals and humans. However, it is not known if a genetic connection exists between the viruses in these regions and, if so, how Severe fever with thrombocytopenia syndrome Virus (SFTSV) is transmitted across China, South Korea, and Japan. We hypothesize that the SFTSV in South Korea share common phylogenetic origins with samples from China and Japan. Further, we postulate that migratory birds, well-known carriers of the tick H. longicornis, are a potential source of SFTSV transmission across countries .
Most SFTSV infections occur through H. longicornis. However, SFTSV infection can also occur between family members, and nosocomial transmission of SFTSV is also possible through close contact with a patient. In this study, we first analyzed clinical, epidemiological, and laboratory data for SFTS patients and family members of an index patient in Korea and we suggest that person-to-person transmission of SFTSV among family members is possible in Korea [2, 3].
To determine prevalence of SFTS in South Korea, we examined serum samples from patients with fever and insect bite history in endemic areas of scrub typhus, is an acute febrile illness caused by Orientia tsutsugamushi, a bacterium transmitted to humans through chigger mite bites. Prevalence of this syndrome among patients suspected of having scrub typhus was high (23.0%, 17/74), suggesting possible co-infection and we also confirmed that a patient was mixed infected with SFTSV and two (Boryong and Taguchi) genotypes of O. tsutsugamushi [4, 5].
1. Phylogenetic Analysis of Severe Fever with Thrombocytopenia Syndrome Virus in South Korea and Migratory Bird Routes Between China, South Korea, and Japan. Am J Trop Med Hyg. 2015, 93:468-474
2. Family Cluster Analysis of Severe Fever with Thrombocytopenia Syndrome Virus Infection in Korea. Am J Trop Med Hyg. 2016, 95(6):1351-1357.
3. Surveillance Results for Family Members of Patients with Severe Fever with Thrombocytopenia Syndrome. Zoonoses and Public Health. 2018, DOI: 10.1111/zph.12481.
4. Wi YM, Woo HI, Park D, Lee KH, Kang CI, Chung DR, Peck KR, Song JH. 2016. Severe Fever with Thrombocytopenia Syndrome in Patients Suspected of Having Scrub Typhus. Emerg Infect Dis. 2016, 22(11):1992-1995.
5. Mixed infection with Severe Fever with Thrombocytopenia Syndrome Virus and Two Genotypes of Scrub Typhus in a Patient, South Korea, 2017. Am. J. Trop. Med. Hyg. 2018 (ACCEPTED on 8th May 2018).
This work was supported by a grant from the Korean Health Technology R&D Project of the Ministry of Health and Welfare, Republic of Korea (grant no. HI15C2891) and a grant obtained from the National Research Foundation of Korea (NRF), the Ministry of Science, ICT, and Future Planning (grant number: NRF- 2016M3A9B6021161).