Vascular endothelial injury in severe fever with thrombocytopenia syndrome caused by the novel bunyavirus

Clinical characteristics and outcomes of disseminated intravascular coagulation in patients with severe fever with thrombocytopenia syndrome

BACKGROUND

Until recently, severe fever with thrombocytopenia syndrome (SFTS)-related disseminated intravascular coagulation (DIC) had not been elucidated. This study aimed to explore the clinical characteristics and outcomes of DIC in patients with SFTS.

METHODS

Patients diagnosed with SFTS who were admitted to Zhongnan Hospital of Wuhan University from August 2016 to October 2023 were included. Patients' demographics and clinical data were collected. According to the presence of DIC, they were assigned into the DIC and non-DIC groups. Independent risk factors for prognosis were identified by univariate and multivariate logistic regression analyses.

RESULTS

A total of 246 consecutive patients diagnosed with SFTS were enrolled, including 216 (87.8%) patients in the non-DIC group and 30 (12.2%) patients in the DIC group. ALT, AST, ALP, GGT, LDH, creatinine, cystatin-C, amylase, lipase, CK, CK-MB, troponin I, BNP, PT, PTA, APTT, TT, FDP, D-dimer, CRP, procalcitonin, IL-6, SAA, ESR, ferritin levels, and viral load were significantly higher in patients with DIC. The cumulative survival rate of patients with DIC was significantly lower than that of patients without DIC. Furthermore, it is demonstrated that the presence of DIC was an independent risk factor for in-hospital mortality of patients with SFTS.

CONCLUSION

DIC is a potential complication and is associated with high mortality in patients with SFTS. Early recognition and timely management of this serious complication are important for patients with SFTS.

Metabolic Profiling Reveals Potential Prognostic Biomarkers for SFTS: Insights into Disease Severity and Clinical Outcomes

Background/Objectives: Severe fever with thrombocytopenia syndrome (SFTS) is a viral infection primarily found in Asia, with a case fatality rate of about 10%. Despite its increasing prevalence, the underlying pathogenic mechanisms remain poorly understood, limiting the development of effective therapeutic interventions. Methods: We employed an untargeted metabolomics approach using liquid chromatography-mass spectrometry (LC-MS) to analyze serum samples from 78 SFTS patients during the acute phase of their illness. Differential metabolic features between survival and fatal cases were identified through multivariate statistical analysis. Furthermore, we constructed a metabolic prognostic model based on these biomarkers to predict disease severity. Results: Significant alterations were observed in four key metabolic pathways: sphingolipid metabolism, biosynthesis of phenylalanine, tyrosine, and tryptophan, primary bile acid biosynthesis, and phenylalanine metabolism. Elevated levels of phenyllactic acid and isocitric acid were strongly associated with adverse outcomes and demonstrated high discriminatory power in distinguishing fatal cases from survivors. The metabolic prognostic model incorporating these biomarkers achieved a sensitivity of 75% and a specificity of 90% in predicting disease severity. Conclusions: Our findings highlight the pivotal role of metabolic dysregulation in the pathogenesis of SFTS and suggest that targeting specific metabolic pathways could open new avenues for therapeutic development. The identification of prognostic biomarkers provides a valuable tool for early risk stratification and timely clinical intervention, potentially improving patient outcomes.

Identification of early prediction biomarkers of severity in patients with severe fever with thrombocytopenia syndrome based on plasma proteomics

Background

Severe fever with thrombocytopenia syndrome (SFTS) is a newly emerging infectious disease. Given its rapid disease progression and high mortality rate, early warning is crucial in improving the outcomes, However, to date, relevant comprehensive predictors or an effective prediction model are still poorly explored.

Methods

A plasma proteomic profile was performed at early stages in patients with SFTS. Functional clustering analysis was used to select the candidate proteins and then validate their expression by ELISA. A cohort consisting of 190 patients with SFTS was used to develop the predictive model for severe illness and subsequently validate it in a new cohort consisting of 93 patients with SFTS.

Results

A significant increase in plasma proteins associated with various functional clusters, such as the proteasomal protein catabolic process, phagocytosis, and humoral immune response, was observed in severe SFTS patients. High levels of four proteins including NID1, HSP90α, PSMA1, and VCAM1 were strongly correlated with multi-organ damage and disease progression. A prediction model was developed at the early stage to accurately predict severe conditions with the area under the curve of 0.931 (95% CI, 0.885, 0.963).

Conclusion

The proteomic signatures identified in this study provide insights into the potential pathogenesis of SFTS. The predictive models have substantial clinical implications for the early identification of SFTS patients who may progress to severe conditions.

Prediction of Prognosis in Patients with Severe Fever with Thrombocytopenia Syndrome

This study aimed to understand the clinical characteristics of severe fever with thrombocytopenia syndrome (SFTS) and identify the risk factors for prognosis. In this retrospective study, we collected epidemiological, demographic, clinical, and laboratory data from 101 patients with SFTS. Patients were divided into survival and deceased groups, and a logistic regression model was used to evaluate the association between the predictors and prognostic variables. A joint detection factor model was constructed, and a receiver operating characteristic curve was drawn. A nomogram was established using the R language, and its efficiency in diagnosing SFTS was evaluated using a calibration curve. Patients in the deceased group were more likely to be older, have a shorter hospitalization stay, and have renal and multiple organ failure than those in the survival group. Statistically significant differences were observed in the neutrophil percentage, lymphocyte percentage, neutrophil-to-lymphocyte ratio, platelet (PLT) count, aspartate aminotransferase (AST)/alanine transaminase (ALT) ratio, AST, blood urea nitrogen, lactate dehydrogenase, hydroxybutyrate dehydrogenase, thromboplastin time, and activated partial thromboplastin time between the two groups. Lymphocyte percentage, PLT count, and the AST/ALT ratio were independent risk factors for mortality in patients with SFTS. Thus, we established a prediction model for SFTS mortality with good efficiency.

Construction and validation of a dynamic nomogram using Lasso-logistic regression for predicting the severity of severe fever with thrombocytopenia syndrome patients at admission

BACKGROUND

Severe fever with thrombocytopenia syndrome (SFTS) is a highly fatal infectious disease caused by the SFTS virus (SFTSV), posing a significant public health threat. This study aimed to construct a dynamic model for the early identification of SFTS patients at high risk of disease progression.

METHODS

All eligible patients enrolled between April 2014 and July 2023 were divided into training and validation sets. Thirty-four clinical variables in the training set underwent analysis using least absolute shrinkage and selection operator (LASSO) logistic regression. Selected variables were then input into the multivariate logistic regression model to construct a dynamic nomogram. The model's performance was assessed using the area under the receiver operating characteristic curve (AUC-ROC), concordance index (C-index), calibration curve, and decision curve analysis (DCA) in both training and validation sets. Kaplan-Meier survival analysis was utilized to evaluate prognostic performance.

RESULTS

299 SFTS patients entered the final investigation, with 208 patients in the training set and 90 patients in the validation set. LASSO and the multivariate logistic regression identified six significant prediction factors: age (OR, 1.060; 95% CI, 1.017-1.109; P = 0.007), CREA (OR, 1.017; 95% CI, 1.003-1.031; P = 0.019), PT (OR, 1.765; 95% CI, 1.175-2.752; P = 0.008), D-dimer (OR, 1.039; 95% CI, 1.005-1.078; P = 0.032), nervous system symptoms (OR, 8.244; 95% CI, 3.035-26.858; P < 0.001) and hemorrhage symptoms (OR, 3.414; 95% CI, 1.096-10.974; P = 0.035). The AUC-ROC, C-index, calibration plots, and DCA demonstrated the robust performance of the nomogram in predicting severity at admission, and Kaplan-Meier survival analysis indicated its utility in predicting 28-day mortality among SFTS patients. The dynamic nomogram is accessible at https://sfts.shinyapps.io/SFTS_severity_nomogram/ .

CONCLUSION

This study provided a practical and readily applicable tool for the early identification of high-risk SFTS patients, enabling the timely initiation of intensified treatments and protocol adjustments to mitigate disease progression.

Prolonged coagulation times in severe fever with thrombocytopenia syndrome virus infection, the indicators of heparin-like effect and increased haemorrhagic risk

Prolonged coagulation times, such as activated partial thromboplastin time (APTT) and thrombin time (TT), are common in patients infected with severe fever with thrombocytopenia syndrome virus (SFTSV) and have been confirmed to be related to patient's poor outcome by previous studies. To find out the reason for prolonged coagulation time in patients with SFTSV infection, and whether it predicts haemorrhagic risk or not. Seventy-eight consecutive patients with confirmed SFTSV infection were enrolled in this prospective, single-centre, observational study. Several global and specific coagulation parameters of these patients on admission were detected, and the haemorrhagic events during hospitalization and their outcomes were recorded. Most of the enrolled patients had prolonged APTT (82.1%) and TT (80.8%), normal prothrombin time (83.3%) and intrinsic coagulation factors above haemostatic levels (97.4%). The heparin-like effect was confirmed by a protamine neutralization test and anti-Xa activity detection in most patients. Interestingly, the APTT and TT results were significantly positively correlated with the levels of endothelial markers and viral load, respectively. The APTT was independently associated with the haemorrhage of patients. The prolonged APTT and TT of SFTS patients may mainly be attributed to endogenous heparinoids and are associated with increased haemorrhagic risk.

Metabolic alterations in urine among the patients with severe fever with thrombocytopenia syndrome

BACKGROUND

The pathogenesis of severe fever with thrombocytopenia syndrome (SFTS) remained unclear. We aimed to profile the metabolic alterations in urine of SFTS patients and provide new evidence for its pathogenesis.

METHODS

A case-control study was conducted in the 154th hospital in China. Totally 88 cases and 22 controls aged ≥ 18 years were enrolled. The cases were selected from laboratory-confirmed SFTS patients. The controls were selected among SFTSV-negative population. Those with diabetes, cancer, hepatitis and other sexually transmitted diseases were excluded in both groups. Fatal cases and survival cases were 1:1 matched. Inter-group differential metabolites and pathways were obtained, and the inter-group discrimination ability was evaluated.

RESULTS

Tryptophan metabolism and phenylalanine metabolism were the top one important metabolism pathway in differentiating the control and case groups, and the survival and fatal groups, respectively. The significant increase of differential metabolites in tryptophan metabolism, including 5-hydroxyindoleacetate (5-HIAA), L-kynurenine (KYN), 5-hydroxy-L-tryptophan (5-HTP), 3-hydroxyanthranilic acid (3-HAA), and the increase of phenylpyruvic acid and decrease of hippuric acid in phenylalanine metabolism indicated the potential metabolic alterations in SFTSV infection. The increase of 5-HIAA, KYN, 5-HTP, phenylpyruvic acid and hippuric acid were involved in the fatal progress of SFTS patients.

CONCLUSIONS

Tryptophan metabolism and phenylalanine metabolism might be involved in the pathogenesis of SFTSV infection. These findings provided new evidence for the pathogenesis and treatment of SFTS.

Cardiac Abnormalities in Patients With Severe Fever With Thrombocytopenia Syndrome: A Systematic Review

Since the identification of severe fever with thrombocytopenia syndrome virus (SFTSV) in 2010, there has been an increase in reported cases in China and other Asian countries. Cardiac abnormalities are highly prevalent in SFTS patients. We searched 5 Chinese and international databases for published SFTS articles and extracted patient characteristics, cardiac complications, electrocardiography findings, and imaging findings. Twenty-seven studies were identified, covering 1938 patients and 621 cardiac abnormalities. Arrhythmia was the most prevalent, reported in 24 studies and 525 cases, with a prevalence of 27.09%. The 2 major types of arrhythmias were bradycardia and atrial fibrillation. Heart failure was the second most prevalent abnormality, with 77 cases. Changes in the ST segment and T wave were the most common. Valve regurgitation, reduced ejection fraction, and pericardial effusion were also documented. We recommend that physicians pay close attention to newly onset arrhythmia and structural heart disease in SFTS patients.

Recent Advances in the Study of the Immune Escape Mechanism of SFTSV and Its Therapeutic Agents

Sever fever with thrombocytopenia syndrome (SFTS) is a new infectious disease that has emerged in recent years and is widely distributed, highly contagious, and lethal, with a mortality rate of up to 30%, especially in people with immune system deficiencies and elderly patients. SFTS is an insidious, negative-stranded RNA virus that has a major public health impact worldwide. The development of a vaccine and the hunt for potent therapeutic drugs are crucial to the prevention and treatment of Bunyavirus infection because there is no particular treatment for SFTS. In this respect, investigating the mechanics of SFTS-host cell interactions is crucial for creating antiviral medications. In the present paper, we summarized the mechanism of interaction between SFTS and pattern recognition receptors, endogenous antiviral factors, inflammatory factors, and immune cells. Furthermore, we summarized the current therapeutic drugs used for SFTS treatment, aiming to provide a theoretical basis for the development of targets and drugs against SFTS.

Liver Function Derangement in Patients with Severe Fever and Thrombocytopenia Syndrome

BACKGROUND AND AIMS

Patients with severe fever with thrombocytopenia syndrome (SFTS) commonly show liver function impairment. This study aimed to characterize the liver function indices in SFTS patients and investigate their association with mortality.

METHODS

Clinical information and laboratory results of 459 laboratory-confirmed SFTS patients, including 78 deceased and 381 surviving patients, were retrospectively analyzed. To explore the infectivity of SFTS caused by novel Bunyavirus (SFTSV) in hepatocytes, Huh7 human hepatoma cells were infected with various concentrations of SFTSV in vitro.

RESULTS

The proportion of SFTS patients developing liver injury during hospitalization was 73.2% (336/459); the hepatocellular injury was the predominant type. The median time to occurrence of liver injury from disease onset was 8 d. Liver injury in the deceased group occurred earlier than that in the surviving group. Alanine aminotransferase (ALT) level between 2-5 times upper limit of normal (ULN) at 4-6 d and between 5-15 ULN at 7-12 d of disease course were independent predictors of mortality. Alkaline phosphatase (ALP) >2 ULN at 7-9 d and elevated ALP at 10-12 days after disease onset were risk factors for death. ALT and aspartate transaminase (AST) levels were correlated with lymphocyte count and platelet-to-lymphocyte ratio (PLR). Total bilirubin (TB), ALT, AST levels showed positive correlation with viral load. In the in vitro experiment, SFTSV infected and replicated inside Huh7 cells.

CONCLUSIONS

Liver injury is common in SFTS patients. ALT and ALP were independent predictors of SFTS-related mortality. Frequent monitoring and evaluation of liver function indices are needed for SFTS patients.

Mast Cell-Derived Proteases Induce Endothelial Permeability and Vascular Damage in Severe Fever with Thrombocytopenia Syndrome

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging hemorrhagic fever acquired by tick bites. Whether mast cells (MCs), the body's first line of defense against pathogens, might influence immunity or pathogenesis during SFTS virus (SFTSV) infection remained unknown. Here, we found that SFTSV can cause MC infection and degranulation, resulting in the release of the vasoactive mediators, chymase, and tryptase, which can directly act on endothelial cells, break the tight junctions of endothelial cells and threaten the integrity of the microvascular barrier, leading to microvascular hyperpermeability in human microvascular endothelial cells. Local activation of MCs (degranulation) and MC-specific proteases-facilitated endothelial damage were observed in mouse models. When MC-specific proteases were injected subcutaneously into the back skin of mice, signs of capillary leakage were observed in a dose-dependent manner. MC-specific proteases, chymase, and tryptase were tested in the serum collected at the acute phase of SFTS patients, with the higher level significantly correlated with fatal outcomes. By performing receiver operator characteristic curve (ROC) analysis, chymase was determined as a biomarker with the area under the curve value of 0.830 (95% CI = 0.745 to 0.915) for predicting fatal outcomes in SFTS. Our findings highlight the importance of MCs in SFTSV-induced disease progression and outcome. An emerging role for MCs in the clinical prognosis and blocking MC activation as a potential drug target during SFTSV infection was proposed. IMPORTANCE We revealed a pathogenic role for MCs in response to SFTSV infection. The study also identifies potential biomarkers that could differentiate patients at risk of a fatal outcome for SFTS, as well as novel therapeutic targets for the clinical management of SFTS. These findings might shed light on an emerging role for MCs as a potential drug target during infection of other viral hemorrhagic fever diseases with similar host pathology as SFTS.

The Endless Wars: Severe Fever With Thrombocytopenia Syndrome Virus, Host Immune and Genetic Factors

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging arboviral infectious disease with a high rate of lethality in susceptible humans and caused by severe fever with thrombocytopenia syndrome bunyavirus (SFTSV). Currently, neither vaccine nor specific antiviral drugs are available. In recent years, given the fact that both the number of SFTS cases and epidemic regions are increasing year by year, SFTS has become a public health problem. SFTSV can be internalized into host cells through the interaction between SFTSV glycoproteins and cell receptors and can activate the host immune system to trigger antiviral immune response. However, SFTSV has evolved multiple strategies to manipulate host factors to create an optimal environment for itself. Not to be discounted, host genetic factors may be operative also in the never-ending winning or losing wars. Therefore, the identifications of SFTSV, host immune and genetic factors, and their interactions are critical for understanding the pathogenic mechanisms of SFTSV infection. This review summarizes the updated pathogenesis of SFTS with regard to virus, host immune response, and host genetic factors to provide some novel perspectives of the prevention, treatment, as well as drug and vaccine developments.

The AST/ALT Ratio (De Ritis Ratio) Represents an Unfavorable Prognosis in Patients in Early-Stage SFTS: An Observational Cohort Study

Background

Severe fever with thrombocytopenia syndrome (SFTS), a widely prevalent infectious disease caused by severe fever with thrombocytopenia syndrome virus (SFTSV) that carries with it a high mortality rate, has emerged to be a public health concern. This study aimed to investigate the epidemiological and clinical characteristics of patients infected with SFTSV, seeking novel prognostic risk factors for SFTS.

Methods

In this retrospective and cross-sectional study, confirmed SFTS patients from the First Affiliated Hospital of Anhui Medical University were enrolled from September 1, 2019, to December 12, 2020. Cases were analyzed for epidemiological, demographic, clinical, and laboratory data. Logistic regression models were used to assess the association between predictors and outcome variables. A generalized additive mixed model (GAMM) was conducted to analyze the trending shift of aspartate aminotransferase/alanine transaminase-ratio (AST/ALT-ratio) and platelet (PLT) in SFTS patients treated with ribavirin. p values ≤ 0.05 were considered statistically significant.

Results

Clinical and laboratory results of 107 hospitalized patients with SFTSV infection were retrospectively described. The mean age at onset of disease was 60.38 ± 11.29 years old and the ratio between male and female was 1:1.2. Fever and thrombocytopenia are hallmark features of SFTS. Furthermore, multiple cases also experienced neurological complications, gastrointestinal/skeletal muscle symptoms together with other non-specific clinical manifestations; laboratory dataset outcomes reported dysregulated levels for routine blood biomarkers, coagulation function, and biochemistry. Overall, 107 patients were segregated into two groups according to patient condition at the clinical endpoint (survivors/non-survivors). SFTS survivors had a higher level of PLT- counts, total protein (TP), and estimated glomerular filtration rate (eGFR), while levels of activated partial thromboplastin time (APTT), thrombin time (TT), D-dimer (D-D), fibrinogen degradation products (FDP), ALT, AST, AST/ALT-ratio, creatinine (Cr), creatine phosphokinase (CK) and procalcitonin (PCT) was higher in non-survivors. Results from univariate Cox regression revealed that elevated levels of FDP, TT, AST/ALT-ratio, PCT, as well as decreased eGFR level and presence of central nervous system symptoms (CNS), were significant predictors for SFTS prognostic, results from multivariate logistic regression analysis in three adjusted models showed AST/ALT-ratio and PCT were independent risk factors for the prognosis of SFTS patients. Kaplan–Meier survival analysis showed that SFTS patients with AST/ALT-ratio >2.683 were associated with a shorter futime (means survival time), therefore indicating an unfavorable prognosis. Treatment with ribavirin could increase PLT count while decreasing AST/ALT-ratio within SFTS patients.

Conclusion

SFTS is an emerging infectious disease, possibly leading to multiple-organ injury; AST/ALT-ratio was an independent risk factor for the prognosis of SFTS patients. Further investigation should be performed in order to gain more knowledge on this disease and guide clinical management.

Screening of a Small Molecule Compound Library Identifies Toosendanin as an Inhibitor Against Bunyavirus and SARS-CoV-2

Severe fever with thrombocytopenia syndrome virus (SFTSV) is an emerging tick-borne virus causing serious infectious disease with a high case-fatality of up to 50% in severe cases. Currently, no effective drug has been approved for the treatment of SFTSV infection. Here, we performed a high-throughput screening of a natural extracts library for compounds with activities against SFTSV infection. Three hit compounds, notoginsenoside Ft1, punicalin, and toosendanin were identified for displaying high anti-SFTSV efficacy, in which, toosendanin showed the highest inhibition potency. Mechanistic investigation indicated that toosendanin inhibited SFTSV infection at the step of virus internalization. The anti-viral effect of toosendanin against SFTSV was further verified in mouse infection models, and the treatment with toosendanin significantly reduced viral load and histopathological changes in vivo. The antiviral activity of toosendanin was further expanded to another bunyavirus and the emerging SARS-CoV-2. This study revealed a broad anti-viral effect of toosendanin and indicated its potential to be developed as an anti-viral drug for clinical use.

Metabolic Syndrome in an Aging Society - Role of Oxidant-Antioxidant Imbalance and Inflammation Markers in Disentangling Atherosclerosis

INTRODUCTION

The prevalence of metabolic syndrome among the elderly population is growing. The elements of metabolic syndrome in an aging society are currently being researched. Atherosclerosis is a slow process in which the first symptoms may be observed after many years. The mechanisms underlying the progression of atherosclerosis are oxidative stress and inflammation. Inflammation and oxidative stress are associated with the increased incidence of metabolic syndrome. Taking the above into consideration, metabolic syndrome is thought to be a clinical equivalent of atherosclerosis.

AIM

The aim of this paper is to review the impact of the interplay of oxidant-antioxidant and inflammation markers in metabolic syndrome in general as well as its components in the pathophysiology which underlies development of atherosclerosis in elderly individuals.

METHODS

A systematic scan of online resources designed for elderly (≥65 years) published from 2005 to the end of 2020 were reviewed. This was supplemented with grey literature and then all resources were narratively analyzed. The analysis included the following terms: "atherosclerosis or metabolic syndrome" and "oxidative stress or inflammation" and "elderly" to find reports of atherosclerotic disease from asymptomatic to life-threatening among the elderly population with metabolic syndrome .

RESULTS

The work summarizes articles that were applicable to this study, including systematic reviews, qualitative studies and opinion pieces. Current knowledge focuses on monitoring the inflammation and oxidant-antioxidant imbalance in disentangling atherosclerosis in patients diagnosed with metabolic syndrome. The population-based studies described inflammation, increased oxidative stress and weak antioxidant defense systems as the mechanisms underlying atherosclerosis development. Moreover, there are discussions that these targets could potentially be a point of intervention to reduce the development of atherosclerosis in the elderly, especially those with altered glucose and lipid metabolism. Specific markers may be used as an approach for the prevention and lifestyle modification of atherosclerotic disease in such population.

CONCLUSION

Metabolic syndrome and its components are important contributors in the progression of atherosclerotic disease in the elderly population but constant efforts should be made to broaden our knowledge of elderly groups who are the most susceptible for the development of atherosclerosis complications.

Severe fever with thrombocytopenia syndrome in Hefei: Clinical features, risk factors, and ribavirin therapeutic efficacy

OBJECTIVES

This study described the clinical features, risk factors, factors affecting the outcome of this disease, and ribavirin therapeutic efficacy for severe fever with thrombocytopenia syndrome (SFTS) patients in Hefei.

METHODS

Between April 2020 and July 2020, 62 cases admitted to the First Affiliated Hospital of Anhui Medical University were included in this study. Serum samples were collected from all patients, after which diagnosis was made via reverse transcription-polymerase chain reaction and via the use of a colloidal gold immunochromatography assay approach.

RESULTS

In multivariate analysis, the following factors were determined as risk factors for SFTS: Being a farmer (odds ratio [OR], 3.033), working in areas with weeds and shrubs (OR, 2.807), and being bitten by a tick (OR, 6.64). The rates of confusion, neck stiffness, viral encephalopathy, and the presence of liver damage were higher in the patients who died than that in the surviving ones. Additionally, the median of alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, creatine phosphokinase, activated partial thromboplastin time, D-dimer, fibrinogen degradation products, creatinine, and urea was also higher in the patients who died. One of the 15 patients treated with ribavirin in the early stage could not survive (6.7%), whereas 11 of the 35 patients treated with ribavirin in the late stage could not survive (31.4%); this difference was statistically significant. However, there was no significant difference in mortality between the untreated group and the other two groups (i.e., patients who started antiviral treatment <5 days from the onset and those who started antiviral treatment ≥5 days from the onset). Moreover, there was no positive effect determined on clinical or laboratory parameters in SFTS patients treated with ribavirin. Also, it was observed that leukocyte levels and platelet levels took longer to return to normal.

CONCLUSIONS

In Hefei, clinical features, prognostic factors, and risk factors associated with SFTS are similar to those in other areas. Patients who were given ribavirin did not have better survival rates than patients who were not given ribavirin.

Risk Factors and Clinical Characteristics of Severe Fever with Thrombocytopenia Syndrome

Purpose

This study was to investigate the clinical characteristics and laboratory parameters of severe fever with thrombocytopenia syndrome (SFTS).

Patients and Methods

A detailed retrospective analysis of clinical records for SFTS patients was conducted. Fifty-one cases confirmed SFTS virus infected were enrolled. The clinical characteristics and laboratory parameters between survivors and non-survivors were analyzed.

Results

All patients aged between 30 and 80 years were farmers or residing in wooded and hilly areas. All patients occurred between April and October. The major clinical manifestations were fever, fatigue, diarrhea, myalgia, nausea and vomiting. Conscious disturbance, lymph node enlargement and hemorrhage were common. Fatal outcome occurred in 31.4% (16/51) of patients. Compared with survivors group, in non-survivors group, the proportion of consciousness disturbance, age, the levels of AST, LDH, Bun, Cr, PT and APTT were significantly increased, and PLT was significantly decreased. The age, PLT, AST, LDH, Cr, PT and APTT were the risk factors for fatal outcomes. Moreover, the age (OR, 1.245; 95% CI, 1.052–1.474) and APTT (OR, 1.095; 95% CI, 1.005–1.192) were the independent risk factors for fatal outcomes. Heteromorphic lymphocyte and hemophagocytosis could be found in SFTS patients, especially the proportion of finding hemophagocytosis was significantly higher in non-survivors group compared with survivors group.

Conclusion

These results suggest SFTS is a systemic infection, the age and APTT can be used as potential predictors referring to severe SFTS cases.

A case of SFTS coinfected with E. coli bacteremia

Background

Severe fever thrombocytopenia syndrome virus (SFTSV) is the causative agent of severe fever thrombocytopenia syndrome (SFTS). SFTS is an emerging infectious disease, characterized by high fever, gastrointestinal symptoms, leukopenia, thrombocytopenia, and a high mortality rate. Until now, little importance has been given to the association of SFTS with leukocytosis and bacterial co-infection.

Case presentation

A 51-year old man visited our hospital with fever and low blood pressure. He was a farmer by occupation and often worked outdoors. He had a Foley catheter inserted due to severe BPH. Laboratory tests revealed thrombocytopenia, elevated liver function, and elevated CRP levels. He had marked leukocytosis, proteinuria, hematuria, and conjunctival hemorrhage. Initially, we thought that the patient was suffering from hemorrhagic fever with renal syndrome (HFRS). However, we confirmed SFTS through PCR and increasing antibody titer. However, his blood culture also indicated E. coli infection.

Conclusion

SFTS displays characteristics of fever, thrombocytopenia, elevated liver function, and leukocytopenia. We described a case of SFTS with leukocytosis due to coinfection with E. coli. Since patients with SFTS usually have leukocytopenia, SFTS patients with leukocytosis are necessarily evaluated for other causes of leukocytosis. Here, we report the first case of an SFTS with concurrent E. coli bacteremia.

Correlation between thrombocytopenia and host response in severe fever with thrombocytopenia syndrome

Severe Fever with Thrombocytopenia Syndrome (SFTS) is an emerging infectious disease caused by a novel bunyavirus, SFTS virus (SFTSV), with fatal outcome developed in approximately 17% of the cases. Thrombocytopenia is a hallmark feature of SFTS, and associated with a higher risk of fatal outcome, however, the pathophysiological involvement of platelet in the clinical outcome of SFTS remained under-investigated. In the current study, by retrospectively analyzing 1538 confirmed SFTS patients, we observed that thrombocytopenia was associated with enhanced activation of the cytokine network and the vascular endothelium, also with a disturbed coagulation response. The platelet phenotypes were also extensively altered in the process of thrombocytopenia development of SFTS patients. More importantly, all these disturbed host responses were related to the severity of thrombocytopenia, thus were considered to play in a synergistic way to influence the disease outcome. Moreover, the clinical effect of platelet transfusion was assessed by comparing two groups of patients with or without receiving this therapy. As a result, we observed no therapy effect in altering frequencies of fatal outcome, clinical bleeding development, or dynamic change of platelet count during the hospitalization. It’s suggested that platelet supplementation alone acted a minor role in improving disease outcome, therefore new therapeutic intervention to regulate host response should be proposed. The current results revealed some evidence of interrelationship between platelet count and clinical outcome of SFTS disease from the perspective of activation of the cytokine network, the vascular endothelium, and the coagulation/fibrinolysis system. These evaluations might help to attain a better understanding of the pathogenesis and therapy choice in SFTS.

Thrombocytopenia in SFTSV is a multifactor-process involving a combination of platelet size or morphology alterations, fibrinolysis activation and coagulation abnormalities, increased inflammatory response and endothelial injury. Platelet supplementation alone shows minor role in improving disease, therefore new therapeutic intervention to regulate host response should be proposed.

Vascular Leak and Hypercytokinemia Associated with Severe Fever with Thrombocytopenia Syndrome Virus Infection in Mice

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging viral hemorrhagic fever (VHF) endemic to China, South Korea, Japan, and Vietnam. Here we characterize the pathogenesis and natural history of disease in IFNAR^-/- mice challenged with the HB29 strain of SFTS virus (SFTSV) and demonstrate hallmark features of VHF such as vascular leak and high concentrations of proinflammatory cytokines in blood and tissues. Treatment with FX06, a natural plasmin digest product of fibrin in clinical development as a treatment for vascular leak, reduced vascular permeability associated with SFTSV infection but did not significantly improve survival outcome. Further studies are needed to assess the role of vascular compromise in the SFTS disease process modeled in IFNAR^-/- mice.

Preexisting chronic conditions for fatal outcome among SFTS patients: An observational Cohort Study

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease that is caused by a novel bunyavirus SFTSV. Currently our knowledge of the host-related factors that influence the pathogenesis of disease is inadequate to allow prediction of fatal outcome. Here we conducted a prospective study of the largest database on the SFTS patients, to identify the presence of comorbidities in SFTS, and estimate their effect on the fatal outcome. Among 2096 patients eligible for inclusion, we identified nine kinds of comorbidities, from which hyperlipidemia (12.2%; 95% CI: 10.8%–13.6%), hypertension (11.0%; 95% CI: 9.6%–12.3%), chronic viral hepatitis (CVH) (9.3%; 95% CI: 8.1%–10.5%), and diabetes mellitus (DM) (6.8%; 95% CI: 5.7%–7.9%) were prevalent. Higher risk of death was found in patients with DM (adjusted OR = 2.304; 95% CI: 1.520–3.492; P<0.001), CVH (adjusted OR = 1.551; 95% CI: 1.053–2.285; P = 0.026) and chronic obstructive pulmonary diseases (COPD) (adjusted OR = 2.170; 95% CI: 1.215–3.872; P = 0.009) after adjusting for age, sex, delay from disease onset to admission and treatment regimens. When analyzing the comorbidities separately, we found that the high serum glucose could augment diseases severity. Compared to the group with max glucose < 7.0 mmol/L, patients with glucose between 7.0–11.1 mmol/L and glucose ≥11.1 mmol/L conferred higher death risk, with the adjusted OR to be 1.467 (95% CI: 1.081–1.989; P = 0.014) and 3.443 (95% CI: 2.427–4.884; P<0.001). Insulin therapy could effectively reduce the risk of severe outcome in DM patients with the adjusted OR 0.146 (95% CI: 0.058–0.365; P<0.001). For CVH patients, severe damage of liver and prolongation of blood coagulation time, as well as high prevalence of bleeding phenotype were observed. These data supported the provocative hypothesis that treating SFTS related complications can attain potentially beneficial effects on SFTS.

SFTS now brings about a substantial global public health concern. Preexisting chronic conditions were thought to increase risk of severe SFTSV infections, however with sparse data mining efforts. In this study, we quantified the frequency of chronic comorbidities in SFTS, estimated their contribution to disease severity, and separately evaluated the effect from diabetes mellitus and chronic viral hepatitis on resulting in fatal outcome.