Epidemiological and Clinical Features of Severe Fever with Thrombocytopenia Syndrome during an Outbreak in South Korea, 2013–2015

Since the first reported case of severe fever with thrombocytopenia syndrome (SFTS) in South Korea in 2013, between 2013 and 2015, we collected 1,697 serum samples from suspected patients who experienced symptoms of SFTS. We performed reverse transcriptase polymerase chain reaction using total RNA extracted from the patients' sera. When viral RNA was detected in the sera, SFTS was diagnosed. Among the 1,697 samples, 170 were positive for SFTS virus. We then analyzed the epidemiologic features of these 170 cases. As a result, we found that the annual number of cases increased steadily. However, the annual case fatality rate exhibited a downward trend. The majority of patients were aged ≥ 60 years, and most cases occurred during May–October in the eastern and southern parts of the country. These results may be useful for effective SFTS control by describing the clinical and epidemiologic features of the disease in South Korea.