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Background Severe fever with thrombocytopenia syndrome (SFTS) virus was first isolated in China in 2009 and has since spread to several Asian countries. SFTS is closely related to environmental factors that accelerate vector growth. We evaluated the associations of SFTS and deforestation with environmental variables. Methods For this observational study, we generated multiple Poisson models using national SFTS outbreak data (2013–2018) and official environmental data for Korea. We included established risk factors as variables. Deforestation was used as the main variable. All variables were analyzed according to their spatial characteristics using the R-INLA package. Results SFTS cases increased over time and peaked in 2017, at 272, followed by a decrease in 2018. Disease mapping showed a high incidence of SFTS nationwide, with particular risks in Gangwon and Gyeonggi Provinces in the north, and Jeju in the south of South Korea. Deforestation was significantly associated with a higher risk of SFTS in the final model (relative risk, 1.751 [95% confidence interval, 1.125–2.743]). Conclusions SFTS outbreaks are associated with deforestation. Therefore, deforestation in Gyeonggi, Gangwon, and Jeju provinces of South Korea needs to be considered in vector-control strategies and active surveillance of SFTS occurrence. [ABSTRACT FROM AUTHOR]

Background: Severe fever with thrombocytopenia syndrome (SFTS) is an emerging zoonotic tick-borne disease in East Asia caused by the SFTS virus (SFTSV). It is to investigate the presence of SFTSV RNA and antibodies in horses from a slaughterhouse and equestrian centers in the Republic of Korea (ROK). A prevalence study of SFTSV-specific RNA and antibodies was designed from 889 horses in the ROK. Materials and Methods: Serum samples were collected from horses at a slaughterhouse and equestrian centers from 2018 to 2020. To detect the presence of SFTSV, RNA was extracted from the serum samples, and a nested reverse transcription-polymerase chain reaction (RT-PCR) was conducted. Sequencing data were analyzed, and a phylogenetic tree was constructed using the maximum-likelihood method with Molecular Evolutionary Genetics Analysis Version 7.0 software. The horse sera were also tested for SFTSV-specific immunoglobulin G antibodies using enzyme-linked immunosorbent assay (ELISA). Results: Twelve of 889 (1.3%) horse sera were positive for SFTSV RNA, and 452 of 887 (51.0%) horse sera were seropositive by ELISA. Among the RT-PCR-positive samples, 12 of the SFTSV S-segment sequences were classified as sub-genotypes B-2 (n = 6) and B-3 (n = 6). ELISA analysis was evaluated by comparison with neutralization test. We investigated SFTSV infection in horses over a 3-year period, but sampling was not performed evenly by season; continuous surveillance of SFTSV in horses is needed. Conclusions: We report the detection of SFTSV RNA and provide serological data on SFTSV prevalence in horses in the ROK. The detection of SFTSV-specific RNA and antibodies in horses, which are in close proximity to humans, suggests that SFTS is an emerging and important health issue, indicating that more attention to its relevance for equestrian workers is needed. [ABSTRACT FROM AUTHOR]

Background Scrub typhus and severe fever with thrombocytopenia syndrome (SFTS) are the 2 most common tick-borne infectious diseases in Korea. Every year, an increasing number of cases are reported, which is a public health concern. Therefore, we aimed to investigate the prevalence of SFTS–scrub typhus coinfection in patients with SFTS. Methods Clinical samples were collected from 129 patients with SFTS. One-step reverse-transcription polymerase chain reaction (PCR) was performed to identify the SFTS virus (SFTSV), and real-time PCR followed by nested PCR was performed to detect the Orientia tsutsugamushi gene for scrub typhus. Phylogenetic analysis was conducted to confirm the evolutionary relationships among different species. Results Among 129 SFTS cases, 2 patients with SFTSV were positive for O. tsutsugamushi with a prevalence of coinfection of 1.6% (95% confidence interval,.001–.06). Phylogenetic analysis confirmed these as O. tsutsugamushi strain Boryong. Conclusions Our study found that 1.6% of patients were coinfected with SFTS and scrub typhus infection. We believe that this information will add a new dimension to clinical diagnosis, which should be considered for better public health management. Further research is needed to better understand the ecological transmission dynamics and geographical distribution of SFTSV and O. tsutsugamushi in endemic countries. [ABSTRACT FROM AUTHOR]

Severe fever with thrombocytopenia syndrome (SFTS) is an arthropod-borne viral disease with a high mortality rate with high fever and thrombocytopenia. We investigated the clinical and epidemiological characteristics and viral genotypes from 2019 to 2021 in Gangwon Province, Korea. Of the 776 suspected cases, 62 were SFTS. The fatality rate was 11.5–28.6% (average rate, 19.4%), and the frequent clinical symptoms were high fever (95.2%), thrombocytopenia (95.2%), and leukopenia (90.3%). Hwacheon had the highest incidence rate per 100,000 persons at 8.03, followed by Inje and Yanggu (7.37 and 5.85, respectively). Goseong, Yangyang, and Hoengseong had rates of 2 or higher; Samcheok, Hongcheon, Jeongsen, and Yeonwol were 1.70–1.98, and Wonju, Gangneung, and Donghae were slightly lower, ranging from 0.31 to 0.74. Of the 57 cases with identified genotypes, eight genotypes (A, B1, B2, B3, C, D, E, and F) were detected, and the B2 genotype accounted for 54.4% (31 cases), followed by the A genotype at 22.8% (13 cases). The B2 and A genotypes were detected throughout Gangwon Province, and other genotypes, B1, B3, C, D, and F, were discovered in a few regions. In particular, genotype A could be further classified into subtypes. In conclusion, SFTS occurred throughout Gangwon Province, and Hwacheon had the highest incidence density. Multiple genotypes of SFTS were identified, with B2 and A being the most common. These findings provide important insights for the understanding and management of SFTS in this region. [ABSTRACT FROM AUTHOR]

Objectives: Severe fever with thrombocytopenia syndrome (SFTS) has no vaccine or treatment and an extremely high fatality rate. We aimed to analyze and evaluate the risk factors for death associated with SFTS. Methods: Among reports from 2018 to 2022, we compared and analyzed 1,034 inpatients aged 18 years or older with laboratory-confirmed SFTS who underwent complete epidemiological investigations. Results: Most of the inpatients with SFTS were aged 50 years or older (average age, 67.6 years). The median time from symptom onset to death was 9 days, and the average case fatality rate was 18.5%. Risk factors for death included age of 70 years or older (odds ratio [OR], 4.82); agriculture-related occupation (OR, 2.01); underlying disease (OR, 7.20); delayed diagnosis (OR, 1.28 per day); decreased level of consciousness (OR, 5.53); fever/chills (OR, 20.52); prolonged activated partial thromboplastin time (OR, 4.19); and elevated levels of aspartate aminotransferase (OR, 2.91), blood urea nitrogen (OR, 2.62), and creatine (OR, 3.21). Conclusion: The risk factors for death in patients with SFTS were old age; agriculture-related occupation; underlying disease; delayed clinical suspicion; fever/chills; decreased level of consciousness; and elevated activated partial thromboplastin time, aspartate aminotransferase, blood urea nitrogen, and creatine levels. [ABSTRACT FROM AUTHOR]

Severe fever with thrombocytopenia syndrome (SFTS) is a zoonotic disease, and its clinical information and prevalence are important. This study was conducted on 22 feline patients from the Republic of Korea (ROK), suspected to suffer from a tick-borne disease. Four cats were positive for SFTS, and genotypes B-1, B-3, D, and F were identified. Clinical symptoms, such as anorexia, jaundice, thrombocytopenia, leukopenia, and hyperbilirubinemia, were detected. This is the first report of SFTS virus genotypes B-1, D, and F from cats in the ROK. Moreover, our results suggest that jaundice may be an indicator of SFTS in cats. [ABSTRACT FROM AUTHOR]

Background: There is a correlation between the severe fever with thrombocytopenia syndrome (SFTS) viral load and disease severity; however, measurement of viral load is difficult in general laboratory and it takes time to obtain a viral load value. Here, the laboratory parameters for predicting the dynamic changes in SFTS viral load were identified. In addition, we tried to evaluate a specific time point for the early determination of clinical deterioration using dynamic change of laboratory parameters. Materials and Methods: This observational study included SFTS patients in Korea (2013 - 2020). Cross-correlation analysis at lagged values was used to determine the temporal correlation between the SFTS viral loads and time-series variables. Fifty-eight SFTS patients were included in the non-severe group (NSG) and 11 in the severe group (SG). Results: In the cross-sectional analyses, 10 parameters -white blood cell, absolute neutrophil cell, lymphocyte, platelet, activated partial thromboplastin time (aPTT), C-reactive protein, aspartate aminotransferase (AST), alanine transaminase (ALT), lactate dehydrogenase (LDH), and creatine phosphokinase (CPK)- were assessed within 30 days from the onset of symptoms; they exhibited three different correlation patterns: (1) positive, (2) positive with a time lag, and (3) negative. A prediction score system was developed for predicting SFTS fatality based on age and six laboratory variables -platelet, aPTT, AST, ALT, LDH, and CPKin 5 days after the onset of symptoms; this scoring system had 87.5% sensitivity and 86.0% specificity (95% confidence interval: 0.831 - 1.00, P <0.001). Conclusion: Three types of correlation patterns between the dynamic changes in SFTS viral load and laboratory parameters were identified. The dynamic changes in the viral load could be predicted using the dynamic changes in these variables, which can be particularly helpful in clinical settings where viral load tests cannot be performed. Also, the proposed scoring system could provide timely treatment to critical patients by rapidly assessing their clinical course. [ABSTRACT FROM AUTHOR]

Severe fever with thrombocytopenia syndrome (SFTS) is a new tick-borne viral disease, and most SFTS virus (SFTSV) infections occur via bites from the tick Haemaphysalis longicornis ; however, SFTSV transmission can also occur through close contact with an infected patient. SFTS is characterized by acute high fever, thrombocytopenia, leukopenia, elevated serum hepatic enzyme levels, gastrointestinal symptoms, and multiorgan failure and has a 16.2 to 30% mortality rate. In this study, we found that age, dyspnea rates, aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase, multiorgan dysfunction score (MODS), viral load, IL-6 levels, and IL-10 levels were higher in patients with fatal disease than in patients with nonfatal disease during the initial clinical course of SFTS. In addition, we found that IL-6 and IL-10 levels, rather than viral load and neutralizing antibody titers, in patients with an SFTSV infection strongly correlated with outcomes (for severe disease with an ultimate outcome of recovery or death). [ABSTRACT FROM AUTHOR]

Severe fever with thrombocytopenia syndrome (SFTS) virus is an emerging zoonotic virus in East Asia. However, SFTS virus (SFTSV) has not been reported to cause clinical infection in companion dogs to date. We report the case of a 4‐year‐old companion dog that presented with fever, vomiting, leukocytopenia and thrombocytopenia at a veterinary hospital in the Republic of Korea. It was diagnosed with SFTS, which was confirmed using real‐time reverse transcription PCR, sequencing and an indirect immunofluorescence assay, and recovered after supportive care. Further studies are required to investigate SFTSV infection in companion animals, living in close contact with humans, as well as animal‐to‐human transmission. [ABSTRACT FROM AUTHOR]

Background: Severe fever with thrombocytopenia syndrome (SFTS) is a tick-borne zoonotic disease that is caused by the SFTS virus (SFTSV), and exhibits an overall mortality rate of approximately 20.0% in Korea. Most cases of this disease have been reported in Korea, East China, and japan, and it mostly affects outdoor workers and farmers. This study aimed to investigate the seroprevalence of SFTSV among healthy farmers on Jeju Island, Korea. Materials and Methods In this prospective cross-sectional study, we analyzed 421 blood samples obtained from 254 farmers (mean age, 59.9 years; 68.9% male) to determine the seroprevalence of SFTSV in 16 rural areas of the Jeju Special Self-Governing Province over a period of 3 years (January 2015-December 2017). We used an enzyme-linked immunosorbent assay to detect immunoglobulin (Ig) G antibodies against SFTSV in the collected samples. Results The seroprevalence of the SFTSV IgG among farmers on Jeju Island was observed to be 2.4%. One subject showed seroposidvity over the entire 3-year study period. The areas with the highest SFTSV IgG seropositivity rates were Seonheul-ri in Jocheon-eup, followed by Namwon-eup. Fruit farmers were at a higher risk of exposure to SFTSV than other farmers. Conclusion The seroprevalence of SFTSV in the healthy agricultural population of Jeju Island was not high. However, personal hygiene management should be implemented for the agricultural population in the endemic areas. Surveillance of mild or asymptomatic infections is required in the endemic regions. [ABSTRACT FROM AUTHOR]

Background: Bites with tick-borne pathogens can cause various bacterial, viral, or parasitic diseases in humans. Tick-transmitted diseases are known as contributing factors to the increasing incidence and burden of diseases. The present article investigated the epidemiology of tick-borne diseases in South Korea. Methods: The incidence and distribution of common tick-borne diseases in Korea (Lyme disease, Q fever, and severe fever with thrombocytopenia syndrome [SFTS]) were investigated and analyzed, using data from the Korea Centers for Disease Control and Prevention (KCDC) infectious disease reporting system. A literature review was compiled on the current status of uncommon tick-borne diseases (Rickettsia, anaplasmosis, ehrlichiosis, bartonellosis, tularemia, tick-borne encephalitis, and babesiosis). Results and Conclusions: In South Korea, SFTS is an emerging disease, showing a rapid increase in reports since 2012, with high mortality. Likewise, reports of Lyme disease and Q fever cases have also been rapidly increasing during 2012–2017, although caution should be taken when interpreting these results, considering the likely influence of increased physician awareness and reporting of these diseases. Other tick-borne diseases reported in South Korea included spotted fever group rickettsiae, anaplasmosis, ehrlichiosis, tularemia, Bartonella, and babesiosis. Evidences on human infection with tick-borne encephalitis virus and Crimean–Congo hemorrhagic fever were recently unavailable, but both need constant monitoring. [ABSTRACT FROM AUTHOR]

배경: Severe fever with thrombocytopenia syndrome virus (SFTSV) is transmitted through tick bites. Q fever is transmitted by inhaling contaminated aerosols, contacting an infected animal, and consuming contaminated dairy products. Ticks are considered a potential Coxiella burnetii vector. This study aimed to analyze SFTSV and C. burnetii infection rates in ticks in rural areas on Jeju Island, South Korea, monthly from 2016 to 2019. 방법: Free ticks were collected from the natural environment, and SFTSV RNA was extracted from the collected ticks. Ribosomal RNA gene sequencing was used to identify Coxiella species, and phylogenetic analyses were conducted. 결과: From the 3,187 ticks collected during the study period, the most common species was Haemaphysalis longicornis (n=3,139; 98.4%), followed by Haemaphysalis flava (n=48; 1.6%). Tick number gradually increased from April, peaked in August (12.4%), and was lowest in March. Of all collected ticks, 2,597 (81.3%) were nymphs; the remaining ticks were adults (18.6%) and larvae (0.1%). SFTSV-infected ticks comprised 390/3,187 (12.2%) of all ticks. The SFTSV-infected ticks were lowest in November–December and increased from January. SFTSV-infected ticks were mostly identified in the adult stage during June–August. Of the SFTSV-infected ticks, C. burnetii co-infection was seen in H. longicornis (4.9%), with the highest infection rate in January, followed by December and November. 결론: Coxiella burnetii-infected ticks were mainly identified in the nymph stage. This region is at high SFTSV risk and potential Q fever endemic. This study provides important information on SFTSV and Q fever risk to humans, according to Korean tick developmental stage. [ABSTRACT FROM AUTHOR]

During 2016-2018, we collected 3,193 ticks from rural areas in South Korea to investigate the prevalence of severe fever with thrombocytopenia syndrome virus (SFTSV). We detected SFTSV in ticks at an infection rate (IR) of 11.1%. We noted increases in the human IR associated with the monthly SFTSV IR in ticks. [ABSTRACT FROM AUTHOR]

Severe fever with thrombocytopenia syndrome (SFTS), a tickborne viral disease, has been identified in China, South Korea, and Japan since 2009. We found retrospective evidence of SFTS virus (SFTSV) infection in Vietnam, which suggests that SFTSV infections also occur in Vietnam, where the virus has not been known to be endemic. [ABSTRACT FROM AUTHOR]

Background SFTS and scrub typhus have similar clinical features and difficult to differentiate. Thus, a study to develop a scoring system to differentiate between two diseases in a clinical setting before the confirmation of laboratory results was reported by Kim et al. However, the statistical power could be low because of low numbers of cases (21 SFTS, 91 scrub typhus), our study analyzed by increasing the number of cases to overcome these limitations. Methods We retrospectively collected data from 183 SFTS and 178 scrub typhus patients who visited the 21 hospitals in South Korea between October, 2013 and November, 2017. The study protocol was approved by the IRB of each institution. SFTS was diagnosed through detection of SFTS viral RNA using RT–PCR. Scrub typhus was diagnosed either detection of 56-kDa antigen of O. tsutsugamushi using nested PCR or ≥ 4 fold rise in IgM or IgG titer using indirect IFA. Statistical analyses were performed by using SPSS and Medcalc. Results To differentiate SFTS from scrub typhus, we applied the scoring system proposed by Kim et al. After multivariable logistic regression, altered mental status, leukopenia, prolonged aPTT, and normal CRP(≤ 1.0 mg/dL) were significantly associated with SFTS compared with scrub typhus. Each variable was scored by 1 point, with a total score of 0–4 points, the optimal cutoff value was > 1 for the ROC curve. A score > 1 had 92% sensitivity, 96% specificity for diagnosis of SFTS, with a ROC AUC of 0.974. Because the sensitivity was less than 95%, we changed the normal CRP criteria to ≤ 3.0 mg/dL. The modified scoring system had 97% sensitivity, 96% specificity for diagnosis of SFTS, with an AUC of 0.983, and it showed a statistically higher accuracy than original scoring system (P = 0.0487). In this study, four factors for predicting SFTS were newly developed: leukopenia, prolonged aPTT, normal CRP (≤3.0 mg/dL), and elevated CK (>1,000 IU/L). Our study scoring system had 97% sensitivity, 98% specificity for diagnosis of SFTS, with an AUC of 0.992, and it showed a statistically higher accuracy than original scoring system (P = 0.0308). Conclusion In conclusion, we can easily differentiate SFTS from scrub typhus by using our scoring system of leukopenia, prolonged aPTT, normal CRP, and elevated CK in the endemic area. Disclosures All authors: No reported disclosures. [ABSTRACT FROM AUTHOR]

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging tickborne infectious disease in China, Korea, and Japan caused by the SFTS virus (SFTSV). SFTS has a high mortality rate due to multiorgan failure. Recently, there are several reports on SFTS patients with mycosis. Here, we report a middle-aged Japanese SFTS patient with invasive pulmonary aspergillosis (IPA) revealed by an autopsy. A 61-year-old man with hypertension working in forestry was bitten by a tick and developed fever, diarrhea, and anorexia in 2 days. On day 4, consciousness disorder was appearing, and the patient was transferred to the University of Miyazaki Hospital. A blood test showed leukocytopenia, thrombocytopenia, as well as elevated levels of alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, and creatine kinase. The SFTSV gene was detected in serum using a reverse-transcription polymerase chain reaction. On day 5, respiratory failure appeared and progressed rapidly, and on day 7, the patient died. An autopsy was performed that revealed hemophagocytosis in the bone marrow and bleeding of several organs. IPA was observed in lung specimens. SFTSV infection may be a risk factor for developing IPA. Early diagnosis and treatment of IPA may be important in patients with SFTS. [ABSTRACT FROM AUTHOR]

Severe fever with thrombocytopenia syndrome (SFTS), a tick-borne infectious disease, is difficult to differentiate from other common febrile diseases. Clinically distinctive features and climate variates associated with tick growth can be useful predictors for SFTS. This retrospective study (2013–2019) demonstrated the role of climatic factors as predictors of SFTS and developed a clinical scoring system for SFTS using climate variables and clinical characteristics. The presence of the SFTS virus was confirmed using reverse transcription polymerase chain reaction (RT-PCR) tests. In the univariate analysis, the SFTS-positive group was significantly associated with higher mean ambient temperature and humidity compared with the SFTS-negative group (22.5 °C vs. 18.9 °C; 77.9% vs. 70.7%, all p < 0.001). In the multivariate analysis, poor oral intake (Odds ratio [OR] 5.87, 95% CI: 2.42–8.25), lymphadenopathy (OR 7.20, 95% CI: 6.24–11.76), mean ambient temperature ≥ 20 °C (OR 4.62, 95% CI: 1.46–10.28), absolute neutrophil count ≤ 2000 cells/μL (OR 8.95, 95% CI: 2.30–21.25), C-reactive protein level ≤ 1.2 mg/dL (OR 6.42, 95% CI: 4.02–24.21), and creatinine kinase level ≥ 200 IU/L (OR 5.94, 95% CI: 1.42–24.92) were significantly associated with the SFTS-positive group. This study presents the risk factors, including ambient temperature and clinical characteristics, that physicians should consider when suspecting SFTS. [ABSTRACT FROM AUTHOR]

Severe fever with thrombocytopenia syndrome virus (SFTSV) is an emerging human pathogen, endemic in areas of China, Japan, and the Korea (KOR). It is primarily transmitted through infected ticks and can cause a severe hemorrhagic fever disease with case fatality rates as high as 30%. Despite its high virulence and increasing prevalence, molecular and functional studies in situ are scarce due to the limited availability of high-titer SFTSV exposure stocks. During the course of field virologic surveillance in 2017, we detected SFTSV in ticks and in a symptomatic soldier in a KOR Army training area. SFTSV was isolated from the ticks producing a high-titer viral exposure stock. Through the use of advanced genomic tools, we present here a complete, in-depth characterization of this viral stock, including a comparison with both the virus in its arthropod source and in the human case, and an in vivo study of its pathogenicity. Thanks to this detailed characterization, this SFTSV viral exposure stock constitutes a quality biological tool for the study of this viral agent and for the development of medical countermeasures, fulfilling the requirements of the main regulatory agencies. [ABSTRACT FROM AUTHOR]

Background Severe fever with thrombocytopenia syndrome (SFTS) is a tick-borne emerging infectious disease caused by SFTS virus (SFTSV). Mortality of SFTS estimated to be 21.8% in South Korea, and this disease is difficult differential diagnosis. Here, we analyzed clinical characteristics between SFTS positive group (SPG) and negative group (SNG) in a primary clinical setting. Methods In this prospective observational study, data were collected on patients with SFTS test performed at the single teaching hospital, in South Korea, between April 2013 and December 2018. The association between each demographic, climatic, clinical, and laboratory variable was assessed. All SFTS was confirmed at the KCDC by detecting the M segment gene of SFTSV RNA using reverse transcription-polymerase chain reaction (RT–PCR), and were confirmed at our laboratory by S segment gene of SFTSV RNA using RT–PCR about patient's family member and those with close contact. Results Of the 199 patients in the study periods, 61 (31%) were SPG and 138 (69%) were SNG. Mean age was 55.1 ± 20.3 years, and 103 (52%) patients were male. In SPG, the comorbidity score and history of tick bite were significantly higher compared with SNG. SPG and SNG were prevalent in summer and autumn, respectively (60.7% vs. 45.7%, P < 0.05). SPG was associated with mean outdoor temperature, humidity and rainfall compared with SNG (22.9°Cvs. 18.9 ℃; 78.8% vs. 70.6%; 12.6 mm vs. 8.5 mm, all P < 0.01). Dizziness, poor oral intake, nausea, and diarrhea were common in SPG. In laboratory findings, white blood cell counts, absolute neutrophil count, and C-reactive protein were significantly lower in SPG. Lymphocyte fraction, activated partial thromboplastin time, and creatinine phosphokinase were significantly higher in SPG. Case fatality of the SPG and SNG were 9.8% and 1.0%, respectively. In multivariate analysis, mean outdoor temperature, humidity, dizziness, and low CRP were predictive factors in SPG. Conclusion Early prediction of SFTS diagnosis is important because this emerging zoonotic disease was a high fatality in endemic areas. When a physician wants to do SFTS test, they would consider according to this predictive variable for differentiating SFTS in primary care settings. Disclosures All authors: No reported disclosures. [ABSTRACT FROM AUTHOR]