Severe Fever With Thrombocytopenia Syndrome Cases Research Articles

Adenosine Deaminase as a Potential Diagnostic and Prognostic Biomarker for Severe Fever with Thrombocytopenia Syndrome.

Severe fever with thrombocytopenia syndrome (SFTS) is a serious infectious disease caused by the Dabie bandavirus, with a high mortality rate. Currently, there are no effective vaccines or specific treatments for SFTS. Early diagnosis and accurate severity assessment are crucial. This study included 171 cases of SFTS, COVID-19, and hepatitis B virus (HBV) patients and healthy controls. We compared the serum adenosine deaminase (ADA) activity across these groups. The diagnostic and prognostic efficiency of serum ADA for SFTS was evaluated by using receiver operating characteristic (ROC) curve analysis. We also examined the correlation between serum ADA in SFTS patients and clinical lab parameters as well as serum cytokines. SFTS patients had significantly higher serum ADA activity than those of COVID-19, HBV patients, and healthy controls. Nonsurvivor SFTS patients had notably higher ADA than survivors. ROC analysis indicated ADA as an effective SFTS diagnostic and prognostic biomarker. ADA correlated with prognosis, viral load, APTT, PT, AST, ferritin, negatively with HDL-c and LDL-c, and positively with cytokines like IL-6, TNF-α, and IL-1β. Multiorgan failure patients showed significant ADA increase. Elevated serum ADA activity in SFTS patients is linked with disease severity and prognosis, showing potential as a diagnostic and prognostic biomarker for SFTS.

Epidemiological characteristics of severe fever with thrombocytopenia syndrome in China, 2018-2021

Objective: To understand the epidemiological characteristics and incidence trend of severe fever with thrombocytopenia syndrome (SFTS) in China. Methods: The incidence data of SFTS in China from 2018 to 2021 were collected from Chinese Disease Prevention and Control Information System for a statistical and descriptive epidemiological analysis by using software such as Excel 2016, Joinpoint 5.0.2, SPSS 26.0, and GraphPad Prism 8.0, especially, the SFTS cases reported monthly by key provinces were analyzed. Results: From 2018 to 2021, a total of 8 835 SFTS cases were reported in 25 provinces and the annual incidence showed an upward trend. The distribution of SFTS cases showed clustering, but the cases were mainly sporadic ones. The cases began to increase in March, mainly occurred during April to October (96.79%,8 551/8 835), and peaked during May to July. The cases were mainly distributed in middle-aged and old farmers, and slight more cases were women. The average case fatality rate was 5.38%, which varied greatly with areas. The case fatality rate tended to increase with age. Conclusion: From 2018 to 2021, the epidemiological characteristics of SFTS in China remained stable, but the number of reported cases gradually increased and the distribution showed an expanding trend, to which close attention should be paid.

Lethal severe fever with thrombocytopenia syndrome virus infection causes systemic germinal centre failure and massive T cell apoptosis in cats.

Severe fever with thrombocytopenia syndrome (SFTS) is a fatal viral disease characterized by high fever, thrombocytopenia, leukopenia, and multi-organ haemorrhage. Disruption of the humoral immune response and decreased lymphocyte numbers are thought to contribute to the disease severity. These findings have been obtained through the analysis of peripheral blood leukocytes in human patients, whereas analysis of lymph nodes has been limited. Thus, in this study, we characterized the germinal centre response and apoptosis in the lymph nodes of cats with fatal SFTS, because SFTS in cats well mimics the pathology of human SFTS. Lymph node tissue sections collected during necropsy from seven fatal SFTS patients and five non-SFTS cases were used for histopathological analysis. Additionally, lymph node tissue sections collected from cats with experimental infection of SFTS virus (SFTSV) were also analysed. In the lymphoid follicles of cats with SFTS, a drastic decrease in Bcl6- and Ki67-positive germinal centre B cells was observed. Together, the number of T cells in the follicles was also decreased in SFTS cases. In the paracortex, a marked increase in cleaved-caspase3 positivity was observed in T cells. These changes were independent of the number of local SFTS virus-positive cell. Furthermore, the analysis of cats with experimental SFTSV infection revealed that the intrafollicular Bcl6- and CD3-positive cell numbers in cats with low anti-SFTSV antibody production were significantly lower than those in cats with high anti-SFTSV antibody production. These results suggest that dysfunction of the humoral response in severe SFTS was caused by the loss of germinal centre formation and massive apoptosis of T cells in the lymph nodes due to systemically circulating viruses.

Epidemiological characteristics and spatio-temporal aggregation of severe fever with thrombocytopenia syndrome in Jinan City, China, 2018-2022.

Severe fever with thrombocytopenia syndrome (SFTS) has become a significant public health issue in Jinan City. However, the analysis of epidemiological characteristics and spatio-temporal clustering of SFTS in Jinan has not been studied yet. SFTS data from 2018-2022 in Jinan City were obtained from the China Information System for Disease Control and Prevention. Global spatial autocorrelation and local spatial autocorrelation analyses were performed using ArcGIS 10.2 software, and spatiotemporal hotspot area detection was carried out using SatScan 9.6 software. Between 2018 and 2022, 680 SFTS cases were reported in Jinan City, resulting in 53 deaths and an average case fatality rate of 7.8%. 99.0% of cases occurred between April and October, 91.9% individuals were over 50 years old, and 87.79% were primarily farmers. A positive spatial correlation of SFTS in Jinan was observed (Moran's I value between 0.135-0.197, P<0.001), indicating spatial aggregation, primarily in Licheng, Zhangqiu, Laiwu, and Gangcheng districts in southeastern Jinan. Spatiotemporal scanning detected one class I and two class II aggregation areas, with the class I aggregation area (RR = 5.66, LLR = 192.547, P<0.001) locating in southeastern Jinan City, comprising 31 towns/streets, and an aggregation time from 13 May 2020 to 13 October 2022. Spatial and temporal aggregation of SFTS is evident in Jinan. Based on the spatial and temporal distribution and epidemiological characteristics, prevention and control measures such as public education, monitoring, and training should target key populations in high-incidence epidemic areas.

High Seroprevalence of Severe Fever with Thrombocytopenia Syndrome Virus Infection among the Dog Population in Thailand.

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging tick-borne zoonotic disease caused by the SFTS virus (SFTSV). In Thailand, three human cases of SFTS were reported in 2019 and 2020, but there was no report of SFTSV infection in animals. Our study revealed that at least 16.6% of dogs in Thailand were seropositive for SFTSV infection, and the SFTSV-positive dogs were found in several districts in Thailand. Additionally, more than 70% of the serum samples collected at one shelter possessed virus-neutralization antibodies against SFTSV and the near-complete genome sequences of the SFTSV were determined from one dog in the shelter. The dog SFTSV was genetically close to those from Thailand and Chinese patients and belonged to genotype J3. These results indicated that SFTSV has already spread among animals in Thailand.

Clinical Characteristics and Diagnostic Prediction of Severe Fever with Thrombocytopenia Syndrome and Rickettsiosis in the Co-Endemic Wakayama Prefecture, Japan.

Background and Objectives: The Wakayama prefecture is endemic for two types of tick-borne rickettsioses: Japanese spotted fever (JFS) and scrub typhus (ST). Severe fever with thrombocytopenia syndrome (SFTS) is a tick-borne hemorrhagic viral disease with a high mortality rate and is often difficult to differentiate from such rickettsioses. SFTS cases have recently increased in Wakayama prefecture. For early diagnosis, this study aimed to evaluate the clinical characterization of such tick-borne infections in the co-endemic area. Materials and Methods: The study included 64 febrile patients diagnosed with tick-borne infection in Wakayama prefecture between January 2013 and May 2022. Medical records of 19 patients with SFTS and 45 with rickettsiosis (JSF, n = 26; ST, n = 19) were retrospectively examined. The receiver operating curve (ROC) and area under the curve (AUC) were calculated to evaluate potential factors for differentiating SFTS from rickettsiosis. Results: Adults aged ≥70 years were most vulnerable to tick-borne infections (median, 75.5 years; interquartile range, 68.5-84 years). SFTS and rickettsiosis occurred mostly between summer and autumn. However, no significant between-group differences were found in age, sex, and comorbidities; 17 (89%) patients with SFTS, but none of those with rickettsiosis, experienced gastrointestinal symptoms such as vomiting, abdominal pain, and diarrhea. Meanwhile, 43 (96%) patients with rickettsiosis, but none of those with SFTS, developed a skin rash. The AUCs of white blood cells (0.97) and C-reactive protein (CRP) levels (0.98) were very high. Furthermore, the differential diagnosis of SFTS was significantly associated with the presence of gastrointestinal symptoms (AUC 0.95), the absence of a skin rash (AUC 0.98), leukopenia <3.7 × 109/L (AUC 0.95), and low CRP levels < 1.66 mg/dL (AUC 0.98) (p < 0.001 for each factor). Conclusions: Clinical characteristics and standard laboratory parameters can verify the early diagnosis of SFTS in areas where tick-borne infections are endemic.

Seroprevalence and transmission of severe fever with thrombocytopenia syndrome virus in a coastal endemic area in Southeastern China

Severe fever with thrombocytopenia syndrome (SFTS) is a newly emerged tick-borne viral zoonosis and widely prevalent in China, Japan and South Korea. Most reported SFTS cases have been identified in mountainous and hilly areas, with a few in island areas. In this study, we conducted a systematic investigation about natural infection of SFTS virus (SFTSV) among humans, animals and ticks in a coastal endemic prefecture, containing island, plains and mountain settings, in Zhejiang Province, Southeastern China. From July 2020 to June 2021, 1117 participants completed a survey with questionnaire interview and serum testing. Meanwhile, 862 serum samples of domestic animals, 275 spleen tissue samples of wild animals and 829 ticks representing five species (predominantly Haemaphysalis longicornis and Rhipicephalus sanguineus sensu lato) were collected. The seroprevalence of anti-SFTSV total antibody and IgM antibody among the participants was 4.8 % (54/1117) and 0.6 % (7/1117), respectively. Multivariate logistic regression analysis indicated that living in the island area (OR=2.66; 95 %CI: 1.04–6.80; P = 0.041) was significantly associated with seropositivity of total antibody to SFTSV. Furthermore, a higher seroprevalence was observed in domestic animals (36.1 %), while the SFTSV-RNA infection rate was 0.4 % in wild animals and the minimum infection rate (MIR) was 0.8 % for all tick species combined. The only tick species infected with SFTSV was H. longicornis. The prevalence of SFTSV infection in the island area, manifested by anti-SFTSV total antibody (P = 0.012) and IgM antibody (P = 0.004) among humans, anti-SFTSV total antibody (P<0.001) among domestic animals, and SFTSV-RNA among ticks (P = 0.022), was significantly higher than that in the mountainous area and the plain area. Furthermore, phylogenetic analysis showed that SFTSV sequences obtained from ticks in the island area were clustered with reported strains in Japan and South Korea. These results suggest that islands in the study area might be an important natural focus of SFTSV.

Clinical characteristics of severe fever with thrombocytopenia syndrome (SFTS) sepsis and non-SFTS sepsis

Severe fever with thrombocytopenia syndrome (SFTS) is a new infectious disease caused by bunyavirus, and the critically cases conform to the definition of sepsis. In order to compare the differences between SFTS sepsis and non-SFTS sepsis, a retrospective analysis was performed. Thirty-seven SFTS sepsis and 96 non-SFTS sepsis patients were enrolled. The clinical characteristics, laboratory results were compared between the two groups and independent prognostic risk of mortality were investigated respectively. Compared with non-SFTS sepsis, SFTS cases had lower white blood cell, neutrophil and platelet counts, prolonged activated partial thromboplastin time and decreased fibrinogen, slightly elevated inflammatory indicators. Interleukin-6 (IL-6), and acute physiology and chronic health evaluation Ⅱ (APACHE II) score were independent prognostic risk factors in non-SFTS sepsis. The mortality risk of STFS sepsis was related to the viral clearance. There was no difference in viral load between SFTS survivors and non-survivors on admission. However, the differences were significant on 5th, 7th, 10th, and 14th day, and all SFTS non-survivors died within 14 days. Viral clearance rate on 7th day was an independent risk factor for mortality in SFTS sepsis. The mortality risk of STFS sepsis was related to the viral clearance rate.

Projecting spatiotemporal dynamics of severe fever with thrombocytopenia syndrome in the mainland of China.

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease with increasing incidence and geographic extent. The extent to which global climate change affects the incidence of SFTS disease remains obscure. We use an integrated multi-model, multi-scenario framework to assess the impact of global climate change on SFTS disease in China. The spatial distribution of habitat suitability for the tick Haemaphysalis longicornis was predicted by applying a boosted regression tree model under four alternative climate change scenarios (RCP2.6, RCP4.5, RCP6.0, and RCP8.5) for the periods 2030-2039, 2050-2059, and 2080-2089. We incorporate the SFTS cases in the mainland of China from 2010 to 2019 with environmental variables and the projected distribution of H. longicornis into a generalized additive model to explore the current and future spatiotemporal dynamics of SFTS. Our results demonstrate an expanded geographic distribution of H. longicornis toward Northern and Northwestern China, showing a more pronounced change under the RCP8.5 scenario. In contrast, the environmental suitability of H. longicornis is predicted to be reduced in Central and Eastern China. The SFTS incidence in three time periods (2030-2039, 2050-2059, and 2080-2089) is predicted to be increased as compared to the 2010s in the context of various RCPs. A heterogeneous trend across provinces, however, was observed, when an increased incidence in Liaoning and Shandong provinces, while decreased incidence in Henan province is predicted. Notably, we predict possible outbreaks in Xinjiang and Yunnan in the future, where only sporadic cases have been reported previously. These findings highlight the need for tick control and population awareness of SFTS in endemic regions, and enhanced monitoring in potential risk areas.

Coinfection With Severe Fever With Thrombocytopenia Syndrome and Scrub Typhus in Korea.

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. 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. 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. 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.

SFTSV infection is associated with transient overproliferation of monoclonal lambda-type plasma cells

The impairment of antibody-mediated immunity is a major factor associated with fatal cases of severe fever with thrombocytopenia syndrome (SFTS). By collating the clinical diagnosis reports of 30 SFTS cases, we discovered the overproliferation of monoclonal plasma cells (MCP cells, CD38+cLambda+cKappa-) in bone marrow, which has only been reported previously in multiple myeloma. The ratio of CD38+cLambda+ versus CD38+cKappa+ in SFTS cases with MCP cells was significantly higher than that in normal cases. MCP cells presented transient expression in the bone marrow, which was distinctly different from multiple myeloma. Moreover, the SFTS patients with MCP cells had higher clinical severity. Further, the overproliferation of MCP cells was also observed in SFTS virus (SFTSV)-infected mice with lethal infectious doses. Together, SFTSV infection induces transient overproliferation of monoclonal lambda-type plasma cells, which have important implications for the study of SFTSV pathogenesis, prognosis, and the rational development of therapeutics.

Epidemiological Characteristics and Risk Factors of Severe Fever With Thrombocytopenia Syndrome in Yantai City, Shandong Province.

To better understand the epidemiological characteristics and risk factors associated with the incidence of severe fever with thrombocytopenia syndrome (SFTS) in Yantai City, Shandong Province, China. The SFTS data from 2010 to 2019 were obtained from the National Notifiable Disease Reporting System, and visualization was performed using ArcGIS 10. A community-based, 1:2 matched case-control study was conducted to investigate the risk factors for SFTS in Yantai City. Standardized questionnaires were used to collect detailed information about the demographics and risk factors for SFTSV infection. A total of 968 laboratory-confirmed SFTS cases were reported, 155 (16.01%) of which were fatal. The SFTS epidemic curve revealed that most cases occurred from May to August, accounting for 77.27% of all studied cases. The SFTS cases were mainly distributed in Lai Zhou, Penglai, Zhaoyuan, Haiyang, and Qixia from 2010 to 2019 (accounting for 83.47% of all cases). No differences in demographics were observed between the cases and controls. In the multivariate analysis, presence of rats in the household (odds ratio [OR] = 2.89, 95% confidence interval [CI] = 1.94-4.30), bitten by the ticks 1 month before the onset of symptoms (OR = 15.97, 95% CI = 5.36-47.60), and presence of weeds and shrubs around the house (OR = 1.70, 95% CI = 1.12-2.60) were found to be the risk factors for SFTS. Our results support the hypothesis that ticks are important vectors of the SFTS virus. Education on SFTS prevention and personal hygiene should be imparted in high-risk populations, especially among outdoor workers living in SFTS-endemic areas, while vector management should also be considered.

Severe fever with thrombocytopenia syndrome virus from ticks: a molecular epidemiological study of a patient in the Republic of Korea

Severe fever with thrombocytopenia syndrome (SFTS) is a tick-borne infectious disease caused by Dabie bandavirus, commonly called SFTS virus (SFTSV). In the Republic of Korea (ROK), 1,504 cases of SFTS have been reported since the first human case was identified in 2013 until 2021. However, no case exists to provide molecular evidence between questing tick and patients with confirmed SFTS in the same living environment. In this study, we investigated the presence of ticks near the area of a patient infected with SFTSV. Ticks were collected by flagging and dry ice-baited traps at three spots in the vegetation around the patients’ residence in Chuncheon City, Gangwon Province (ROK). Among the tick samples collected, the presence of SFTSV was genetically determined using reverse transcription PCR, followed by the phylogenetic analysis of the tick virus sequences and SFTSV found in the patient. In total 1,212 Haemaphysalis longicornis ticks were collected, and SFTSV was detected at a minimum infection rate of 5.3% (33 pools/618 tested ticks). The sequences of SFTSV in ticks were 99.6–100% identical with the patient’s SFTSV in the M segment. To the best of our knowledge, this study is the first case to provide a molecular correlation between SFTSV in questing ticks collected from residence and patient with SFTS in the ROK. The present results provide useful information for the epidemiological investigation of patients with SFTS using ticks as vectors of SFTSV.

Analysis of spatial-temporal distribution characteristics and natural infection status of SFTS cases in Hefei from 2015 to 2021.

To analyze the prevalence and spatial-temporal characteristics of severe fever with thrombocytopenia syndrome (SFTS), clustering mode of transmission, and the serological dynamic detection results in multiple areas in Hefei from 2015 to 2021, and to provide the basis for SFTS prevention and control. Case data were obtained from the Chinese Disease Control and Prevention Information System. Information on the clustering outbreak was obtained from the outbreak investigation and disposal report. Population latent infection rate information was obtained from field sampling in multiple-incidence counties in 2016 and 2021 by multi-stage random sampling. Epi data3.2 and SPSS 16.0 softwares were used to perform a statistical analysis of the data on SFTS cases, and QGIS 3.26 software was used to draw the incidence map with township (street) as unit. The an average annual reported incidence rate of SFTS in Hefei from 2015 to 2021 was 0.65/100,000, and the case fatality rate was 9.73%. The overall prevalence of SFTS epidemics in Hefei City showed a fluctuating upward trend from 2015 to 2021 (χ2trends = 103.353, P < 0.001). Chaohu City, Feixi County, Feidong County and Lujiang County ranked the top 4 in the city in terms of average annual incidence rate. The number of epidemic-involved towns (streets) kept increasing ((χ2trend = 47.640, P = 0.000)). Co-exposure to ticks accounted for the majority of clustered outbreaks and also human-to-human outbreaks. Population-based latent infection rate surveys were conducted in four SFTS multi-incidence counties, with 385 people surveyed in 2016 and 403 people surveyed in 2021, increasing the population-based latent infection rate from 6.75% to 10.91%, just as the incidence rate increased. The incidence rate of SFTS in Hefei is obviously regional, with an expanding trend in the extent of the epidemic involved. Co-exposure to ticks accounted for the majority of clustered outbreaks and the latent infection rate cannot be ignored.

Epidemiologic and Clinical Characteristics of Patients with Severe Fever with Thrombocytopenia Syndrome at Tertiary Hospital in Jeju for 10 years.

Severe fever with thrombocytopenia syndrome (SFTS), which was first discovered in China in 2009, is an infectious disease with a high mortality rate, particularly in East Asia. This study aimed to investigate the epidemiological and clinical characteristics and risk factors for mortality by analyzing SFTS cases accumulated for up to ten years in Jeju, Korea. Medical records of patients diagnosed with SFTS between March 2013 and August 2022 at a tertiary hospital in Jeju were analyzed retrospectively. We investigated data of patients with SFTS on the epidemiologic and clinical characteristics, laboratory findings, and administered treatments and compared the differences between fatal and non-fatal groups. We enrolled 91 SFTS-confirmed patients. The median age of patients was 62 years, and the fatality rate increased with age (P = 0.004). Fever was the most common symptom (84.6%), and diarrhea (37.4%) was also present in some cases. The overall fatality rate was 10.9%. Dyspnea (20.0% vs. 0.0%, P = 0.009) and changes in mental status (70.0% vs. 11.0%, P <0.001) were more frequent in fatal cases. Risk factor assessment revealed that a high aspartate aminotransferase /alanine aminotransferase ratio (odds ratio [OR]: 39.568, 95% confidence interval [CI]: 1.479 - 1,058.639, P = 0.028) and elevated total bilirubin levels (OR: 53.037, 95% CI: 1.064 - 2,643.142, P = 0.046) were also significantly associated with fatal cases. Plasma exchange (40.7%) was the most commonly administered treatment. SFTS has a high mortality rate; therefore, awareness of SFTS must be raised among physicians and citizens living in tick-inhabited areas, such as Jeju.

Severe fever with thrombocytopenia syndrome incidence could be associated with ecotone between forest and cultivated land in rural settings of central China

Severe fever with thrombocytopenia syndrome (SFTS), an emerging tick-borne disease first reported in rural areas of central China, has become a major public health concern in endemic areas. The epidemic dynamic and ecologic factors of SFTS incidence at a village scale remain unclear. Here we analyzed the epidemiological characteristics of SFTS cases in Shangcheng County, the first reported areas of SFTS in China. A retrospective space-time cluster analysis was conducted to identify the dynamics of hotspot areas, and the negative binomial regression model was conducted to examine potential factors contributing to the incidence of SFTS at the village level. A total of 1,219 SFTS cases were reported in Shangcheng County from 2011 to 2020, with a case fatality rate of 12.0%. The median age of patients was 64 years, and 81.7% of patients were over 50 years old. Women accounted for 60.3% of all cases, and the incidence rate was significantly higher than that of men (Pearson χ2 test, P<0.001). Five spatial-temporal clusters were identified, and mostly distributed in the central part of the county. Higher risk of SFTS incidence was shown in villages with higher percentage coverages of forest and tea plantation, and higher goat density. In villages where the ratio of cultivated land area to forest land area was between 0.2 and 1.2, the risk of SFTS incidence increased significantly, with an incidence rate ratio of 1.33 (95% CI: 1.04‒1.72, p = 0.024). Our findings indicated that ecotone between forest and cultivated land might be the most important risk settings for exposure and infection with SFTS virus in endemic areas of central China. Precise identification of risk factors and high-risk areas at a suitable scale is conducive to carrying out targeted measures and improving the surveillance of the disease.

Analysis of the spatial-temporal components driving transmission of the severe fever with thrombocytopenia syndrome in Shandong Province, China, 2016-2018.

Existing models about the spatial-temporal distribution of the severe fever with thrombocytopenia syndrome (SFTS) entirely concentrate on aggregation, which provides limited knowledge to develop effective measures to control the epidemic of SFTS. This study aimed to identify the main spatial-temporal components and heterogeneity in different regions in Shandong Province, China. We applied the spatial-temporal multicomponent model to detect the spatial-temporal component values. A total of 2814 cases were reported from 2016 to 2018 in Shandong Province. The prevalence rate was 0.627 per 100,000, with an overall case fatality rate of 8.99%. SFTS cases were mostly clustered in central and eastern regions of Shandong Province. The total effect values of the autoregressive component, the spatiotemporal component and the endemic component were 0.586, 0.244 and 0.084, respectively, which demonstrated that the autoregressive component was the main factor driving the incidence of SFTS, followed by the spatiotemporal component. Gross domestic product per capita and weekly mean atmospheric pressure contributed to the incidence of SFTS with inverse effects. Obvious heterogeneity across regions for the autoregressive component and the spatiotemporal component was identified. In conclusion, the autoregressive and spatiotemporal components play a key role in driving the transmission of SFTS in Shandong Province. Based on the main component values, targeted measures should be formulated to control SFTS epidemics in different regions.

Spatiotemporal analysis of severe fever with thrombocytopenia syndrome in Shandong Province, China, 2014–2018

BackgroundDue to recent emergence, severe fever with thrombocytopenia syndrome (SFTS) is becoming one of the major public health problems in Shandong Province, China. The numbers of reported SFTS cases in general and the area with reported SFTS cases are both continuously increasing in recent years. However, spatiotemporal patterns and clusters of SFTS in Shandong Province have not been investigated yet.MethodsThe surveillance data of SFTS in Shandong Province, China, during 2014–2018 were extracted from China Information System for Disease Control and Prevention (CISDCP). Geoda software was used to explore spatial autocorrelation analysis, and Satscan software was used to identify spatio-temporal clustering of cases. The results were presented in ArcMap.ResultsThe annual average incidence was 0.567/100,000 in Shandong Province during 2014–2018. Results showed that the distribution of SFTS was not random but clustered in space and time. A most likely cluster including 15 counties was observed in the northeastern region of Shandong Province from January 1, 2015 to December 31, 2015 (Relative risk = 5.13, Log likelihood ratio = 361.266, P < 0.001).ConclusionsThe number of SFTS cases in Shandong Province increased overall. Geographic information system analysis coupled with spatial analysis illustrated regions with SFTS clusters. Our results provide a sound evidence base for future prevention and control programs of SFTS such as allocation of the health resources, surveillance in high-risk regions, health education, improvement of diagnosis and so on.

Antiviral Treatment Options for Severe Fever with Thrombocytopenia Syndrome Infections.

Severe fever with thrombocytopenia syndrome virus (SFTSV) is a tick-borne virus that produces severe fever with thrombocytopenia syndrome (SFTS). It is widespread in Japan, South Korea, and Central and Eastern China. The epidemic has developed rapidly through China in recent years. SFTS cases have been reported in 25 provinces in China, mainly distributed in rural areas in mountainous and hilly areas. The infection has a high case fatality rate and no specific treatments or vaccinations. Therefore, early diagnosis and treatment of SFTS infection is important to survival and disease control. In this article, we provide an overview on different aspects of SFTS with an emphasis on management, to explore the current treatment and prophylactic measures further.

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.