Epidemiological features of severe fever with thrombocytopenia syndrome in South Korea in 2016

Park Sun-Whan, Ryou Jungsang, Lee Won-Ja, and Lee Joo-Yeon
Division of Emerging Infectious Disease and Vector Research, Center for Infectious Diseases Research, KNIH, KCDC

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease caused by the SFTS virus, which belongs to the genus of Phlebovirus (family Phenuiviridae). The major clinical symptoms and laboratory parameters of SFTS are fever, thrombocytopenia, leukopenia, and elevated serum hepatic enzymes. Fatality of patients with SFTS usually occurs due to multiple organ failure. Since the first case of SFTS in South Korea in 2013, we have conducted laboratory diagnoses for suspected cases. We collected serum samples from 1,388 hospitalized patients who experienced symptoms of SFTS in 2016. Of the 1,388 patients, 162 tested positive for SFTS virus. We then analyzed the epidemiological features of these 162 patients. We found that the annual number of cases increased sharply; however, the annual case fatality rate decreased by about 12%. Of the 162 patients, 148 (91.3%) were aged ≥ 50 years, and SFTS cases began to emerge in April and decreased in November. The highest number of cases was reported in October (62 cases). An understanding of clinical and epidemiological features of SFTS, as demonstrated in this study, may be useful for effective control of SFTS transmission.

Keywords: Severe fever with thrombocytopenia syndrome, Phlebovirus, Thrombocytopenia, Leukopenia