Severe Fever with Thrombocytopenia Syndrome Patients with Hemophagocytic Lymphohistiocytosis Retrospectively Identified in Korea, 2008–2013

The incidence of severe fever with thrombocytopenia syndrome (SFTS) has increased in Korea since a first report in 2013. We investigated whether SFTS existed before 2013 using real-time reverse transcription polymerase chain reaction and stored blood samples from febrile patients with thrombocytopenia. Four cases of SFTS were identified, with the earliest occurring in 2008.

The Most Common Mite- and Tick-borne Infectious Diseases in Korea: Scrub Typhus and Severe Fever Thrombocytopenia Syndrome / 대한내과학회지

The incidence of mite- and tick-borne infectious disease is increasing with climate change and the development of diagnostic tools. Tick-borne infectious diseases include Lyme disease, anaplasmosis, ehrlichiosis, severe fever with thrombocytopenia syndrome (SFTS), and Japanese spotted fever. Rickettsial pox and scrub typhus are mite-borne infectious diseases. Scrub typhus and SFTS are the most common mite- and tick-borne infectious diseases in Korea, respectively. They are often difficult to diagnose at an early stage of disease. To make a definite diagnosis of mite- and tick-borne infectious disease, polymerase chain reaction (PCR) tests or serologic testing for antibodies during the acute and convalescent periods are necessary. If patients with nonspecific symptoms, such as fever, headache, nausea, and vomiting, have a history of outdoor activity or a tick bite, it is reasonable to consider the possibility of mite- or tick-borne infectious diseases clinically. There are no vaccinations against mite- and tick-borne infectious diseases. Therefore, preventing mite or tick bites is the best way to prevent the diseases.

In vitro antiviral activity of ribavirin against severe fever with thrombocytopenia syndrome virus

BACKGROUND/AIMS: Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease caused by severe fever with thrombocytopenia syndrome virus (SFTSV), a novel bunyavirus. As yet, there is no effective antiviral therapy for SFTS. Ribavirin is a broad-spectrum antiviral agent, which has been tried for treatment of SFTS. In this study, antiviral activity of ribavirin against SFTSV has been investigated. METHODS: Vero cell-grown SFTSV strain Gangwon/Korea/2012 was treated with ribavirin at various concentrations. Antiviral activity of ribavirin was evaluated by inhibition of the SFTSV cytopathic effect in Vero cells and quantification of viral RNA load in culture supernatant using one-step real-time reverse transcription polymerase chain reaction. Cytotoxicity of ribavirin was determined by a tetrazolium-based colorimetric method. RESULTS: Ribavirin reduced SFTSV titers in a dose-dependent manner, with a half-maximal inhibitory concentration ranged from 3.69 to 8.72 μg/mL. Cytopathic effects were reduced as ribavirin concentration increased. No significant cytotoxicity was detected at ribavirin concentrations of ≤ 31.3 μg/mL. CONCLUSIONS: Ribavirin exhibited inhibitory activity against SFTSV replication in vitro, which suggests that ribavirin can be used as a potential antiviral agent for SFTS.

A Pediatric Case of Severe Fever with Thrombocytopenia Syndrome in Korea

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease and elderly people living in rural areas have the greatest risk of infection. We report the first pediatric case of SFTS in Korea and the clinical characteristics and disease progression in children. A 10-year-old child from Chonnam province visited the hospital with myalgia and a history of fever over the previous 8 days. Her father noticed a tick on her head and removed it before fever developed. Because the symptoms continued, her father consulted the community health center and SFTS virus was detected both from the tick (Haemaphysalis longicornis) and the patient's blood. On hospitalization, fever and severe myalgia were improved and no gastrointestinal and hemorrhagic symptoms were observed. The patient was successfully treated with a combination of steroids, IVIG, and ribavirin. In this report, a pediatric case of SFTS presents a mild clinical course but close attention must be paid to the screening of children with mild symptoms consisting of SFTS.

Effect of Early Plasma Exchange on Survival in Patients with Severe Fever with Thrombocytopenia Syndrome: A Multicenter Study

Despite a high mortality rate, no specific treatment for severe fever with thrombocytopenia syndrome (SFTS) has been established. This study compared the clinical outcomes of SFTS patients treated with plasma exchange (PE group) with those who were not treated (non-PE group) at nine Korean hospitals between May 2013 and August 2015. A total of 53 SFTS patients were included: 24 (45.3%) PE cases and 29 (54.7%) non-PE cases. The overall in-hospital mortality rate was 32.1% (17/53). The in-hospital mortality rate of the PE group did not differ from that of the non-PE group (29.3% vs. 34.5%, p=0.680). Of the 24 PE cases, 16 (66.7%) were treated with PE within 7 days of symptom onset (early PE group). The early PE group survived longer than the non-PE group (mean 28.4 days vs. 22.6 days, p=0.044). Multivariate analysis showed an inverse association between early PE implementation and 30-day mortality (adjusted hazard ratio 0.052, 95% confidence interval 0.004–0.678, p=0.024). The results of this study suggest that early PE implementation may have a beneficial effect on the clinical outcome of SFTS patients.

Severe Fever with Thrombocytopenia Syndrome / 대한내과학회지

Severe fever with thrombocytopenia syndrome (SFTS) is firstly reported in China in 2011. It is an emerging infectious disease in China, Japan and South Korea. It is caused by novel bunyavirus, called SFTS virus. The vector of SFTS is Haemaphysalis longicornis tick and domesticated animals may serve as intermediate hosts. The clinical manifestations of SFTS are fever, vomiting, diarrhea, thrombocytopenia and leukopenia. In severe cases, multiple organ failure, disseminated intravascular coagulopathy, and central nervous systems manifestation are present. The case-fatality rate is 6-30%. There is no effective antiviral therapy and supportive care is the main treatment.

Severe Fever with Thrombocytopenia Syndrome / 대한구급학회지

Severe fever with thrombocytopenia syndrome (SFTS) is a newly emerging infectious disease, caused by a novel species of Phlebovirus of Bunyaviridae family, in China, South Korea, and Japan. SFTS is primarily known as a tick-borne disease, and human-to-human transmission is also possible in contact with infectious blood. Common clinical manifestations include fever, thrombocytopenia, and leukopenia as initial symptoms, and multiple organ dysfunction and failure manifest with disease progression. Whereas disease mortality is reported to be 12% to 30% in China, a recent report of cumulative SFTS cases indicated 47% in Korea. Risk factors associated with SFTS were age, presence of neurologic disturbance, serum enzyme levels, and elevated concentrations of certain cytokines. Diagnosis of SFTS is based on viral isolation, viral identification by polymerase chain reaction, and serologic identification of specific immunoglobulin G. Therapeutic guideline has not been formulated, but conservative management is the mainstream of treatment to prevent disease progression and fatal complications.