Severe Fever with Thrombocytopenia Syndrome, South Korea, 2012

Kye-Hyung Kim¹, Jongyoun Yi¹, Gayeon Kim, Su Jin Choi, Kang Il Jun, Nak-Hyun Kim, Pyoeng Gyun Choe, Nam-Joong Kim, Jong-Koo Lee, and Myoung-don Oh

Author affiliations: Seoul National University College of Medicine, Seoul, South Korea (K.-H. Kim, G. Kim, S.J. Choi, K.I. Jun, N.-H. Kim, P.G. Choe, N.-J. Kim, J.-K. Lee, M.-D. Oh); Pusan National University School of Medicine, Busan, South Korea (J. Yi)

Abstract

We report a retrospectively identified fatal case of severe fever with thrombocytopenia syndrome (SFTS) in South Korea from 2012. SFTS virus was isolated from the stored blood of the patient. Phylogenetic analysis revealed this isolate was closely related to SFTS virus strains from China and Japan.

Severe fever with thrombocytopenia syndrome (SFTS) causes signs and symptoms including high fever, vomiting, diarrhea, thrombocytopenia, leukopenia, and multiple organ failure and has a 6%–30% case-fatality rate (1–4). Caused by a novel bunyavirus, SFTS virus (SFTSV), SFTS was initially reported in China in 2011 (1). SFTSV has been detected in Haemaphysalis longicornis ticks, which have been implicated as a vector of the virus (1). H. longicornis ticks widely inhabit the Korean Peninsula (5,6), and the Korea Centers for Disease Control and Prevention reported that SFTSV was detected in samples from H. longicornis ticks collected during 2011–2012 in South Korea (7). Seroconversion and viremia of SFTSV have been demonstrated in domesticated animals such as goats, sheep, cattle, pigs, and dogs; these animals have been implicated as intermediate hosts in SFTSV-endemic areas (8,9). SFTSV was also detected in Japan in February 2013 (10). We report a retrospectively identified case of SFTS in South Korea from 2012 and the characterization of the SFTSV isolated from the patient.

The Study

On August 3, 2012, fever developed in a previously healthy 63-year-old woman who lived in Chuncheon-si, Gangwon Province, South Korea; the same day, she noticed a lump on the left side of her neck. She visited a local clinic, and ciprofloxacin and ceftriaxone were started on the first day of illness. The patient reported that, 2 weeks before her fever started, she noticed an insect bite on her neck while she was working on a crop farm in Hwacheon-gun, Gangwon Province (in the northernmost part of South Korea). She did not recall having contact with any domestic animals on the farm and had no history of travel outside South Korea in the month before illness onset.
On the third day of her illness, she began having watery diarrhea, 6 times per day. On the fourth day of the illness, thrombocytopenia and leukopenia were recorded at the local clinic (Table). Because of worsening thrombocytopenia, she was transferred to another hospital. Ciprofloxacin was changed to doxycycline, and ceftriaxone was continued. A computed tomography scan of the neck showed an enlarged (1.6 cm), necrotic lymph node. Multiple lymph nodes on the left cervical and left axillary areas were also swollen. On the sixth day, the patient was transferred to Seoul National University Hospital.