Severe fever with thrombocytopenia syndrome (SFTS) is an acute febrile illness characterized by fever, leukopenia, thrombocytopenia, and gastrointestinal symptoms such as diarrhea, nausea, and vomiting resulting from infection with the SFTS virus (SFTSV). The SFTSV is transmitted to humans by tick bites, primarily from Haemaphysalis longicornis, Amblyomma testudinarium, Ixodes nipponensis, and Rhipicephalus microplus. Human-to-human transmission has also been reported. Since the first report of an SFTS patient in China, the number of patients has also been increasing. The mortality rate of patients with SFTS remains high because the disease can quickly lead to death through multiple organ failure. In particular, an average fatality rate of approximately 20% has been reported for SFTS patients, and no treatment strategy has been established. Therefore, effective antiviral agents and vaccines are required. Here, we aim to review the epidemiology, clinical manifestations, laboratory diagnosis, and various specific treatments (i.e., antiviral agents, steroids, intravenous immunoglobulin, and plasma exchange) that have been tested to help to cope with the disease.

Kim Y, et al. Infect Chemother. 2022 Jul;54:e70. https://doi.org/10.3947/ic.2022.0141

Seo JW, et al. Infect Chemother. 2024 Mar;56:e11. https://doi.org/10.3947/ic.2024.0024

Antiviral treatment reduces the severity and mortality of SARS-CoV-2 infection; however, its effectiveness against long COVID-19 is unclear. This study aimed to evaluate the effectiveness of antiviral drugs in preventing long COVID and related hospitalizations/deaths. Scientific and medical databases were searched from 1 January 2020 to 30 June 2023. We included observational cohort studies comparing individuals receiving early antiviral therapy for COVID-19 and those receiving supportive treatment. A fixed-effects model was used to merge the effects reported in two or more studies. The risk of post-acute sequelae of COVID-19 (PASC) was combined as an odds ratio (OR). Six studies were selected, including a total of 3,352,235 participants. The occurrence of PASC was 27.5% lower in patients who received antiviral drugs during the early stages of SARS-CoV-2 infection (OR = 0.725; 95% confidence interval [CI] = 0.409–0.747) than in the supportive treatment group. Moreover, the risk of PASC-associated hospitalization and mortality was 29.7% lower in patients receiving early antiviral therapy than in the supportive treatment group (OR = 0.721; 95% CI = 0.697–0.794). Early antiviral therapy was associated with a reduced risk of PASC and related hospitalization or death. Thus, early antiviral therapy is recommended for at-risk individuals.

Background: Severe fever with thrombocytopenia syndrome (SFTS) is an acute, febrile, and potentially fatal tick-borne disease caused by the SFTS Phlebovirus. Here, we evaluated the effects of steroid therapy in Korean patients with SFTS. Methods: A retrospective study was performed in a multicenter SFTS clinical cohort from 13 Korean university hospitals between 2013 and 2017. We performed survival analysis using propensity score matching of 142 patients with SFTS diagnosed by genetic or antibody tests. Results: Overall fatality rate was 23.2%, with 39.7% among 58 patients who underwent steroid therapy. Complications were observed in 37/58 (63.8%) and 25/83 (30.1%) patients in the steroid and non-steroid groups, respectively (P < .001). Survival analysis after propensity score matching showed a significant difference in mean 30-day survival time between the non-steroid and steroid groups in patients with a mild condition [Acute Physiology and Chronic Health Evaluation II (APACHE II) score 5 days), and non-steroid groups, were 18.4, 22.4, and 27.3 days, respectively (P = .005). Conclusions: After steroid therapy, an increase in complications was observed among patients with SFTS. Steroid therapy should be used with caution, considering the possible negative effects of steroid therapy within 5 days of symptom onset or in patients with mild disease (APACHE II score <14).

The clinical characteristics and the effect of viral RNA loads on fatality in 56 patients with severe fever with thrombocytopenia syndrome (SFTS) were analyzed. The non-survival group (12 patients) demonstrated a significantly higher mean age (77 years) than the survival group (44 patients, 65 years) (p = 0.003). The survival rates were 91.7% and 8.3% in patients with Ct values ≥30 and differed significantly (p = 0.001) in the survival and non-survival groups, respectively. The survival rates were 52.4% and 47.6% in patients with viral copy numbers ≥10,000 and 94.3% and 5.7% in patients with viral copy numbers <10,000 in the survival and non-survival groups, respectively (p = 0.001). In a multivariate analysis, viral copy numbers and initial Acute Psychologic Assessment and Chronic Health Evaluation II (APACHE II) scores were identified as the factors affecting fatality (p = 0.015 and 0.011, respectively). SFTS viral RNA loads can be useful markers for the clinical prediction of mortality and survival.