Background: Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease with the high case-fatality rate, and lack of vaccines. We aimed to systematically analysed the epidemiological characteristics, clinical signs, routine laboratory diagnosis, risk factors, and outcomes. Methods: Documents on SFTS were collected by searching the Chinese National Knowledge Infrastructure, Wan Fang Data, PubMed, Embase, and Web of Science databases from 2011 to 2018. Meta-analysis was performed by using Review Manager and Stata software. Results: Twenty-five articles involving 4143 cases were included. Diarrhea (odds ratio (OR) =1.60, 95% confidence interval (CI): 1.06 to 2.42, P = 0.02), and vomiting (OR = 1.56, 95% CI: 1.01 to 2.39, P = 0.04) on admission were associated with the fatal outcomes of SFTS. Compared to patients with mild symptoms, patients with severe symptoms had significantly elevated levels of lactic acid dehydrogenase (standard mean difference (SMD) =1.27, 95% CI: 0.59 to 1.94), alanine aminotransferase (SMD = 0.55, 95% CI: 0.24 to 0.85), aspirate aminotransferase (SMD = 1.01, 95% CI: 0.69 to 1.32), and creatine kinase (SMD = 1.04, 95% CI: 0.74 to 1.33) but had reduced platelet counts (SMD = -0.87, 95% CI: − 1.16 to − 0.58) and albumin levels (SMD = -1.00, 95% CI: − 1.32 to − 0.68). The risk factors for poor prognosis included age (mean difference (MD) =6.88, 95% CI: 5.41 to 8.35) and farming (OR = 2.01, 95% CI: 1.06 to 3.80). For the risk factors of contracting SFTS, the incidence of SFTS related to tick bites was 24% [95% CI: 0.18 to 0.31]. The pooled case-fatality rate of SFTS patients was 18% [95% CI: 0.16 to 0.21]. Conclusions: China is the country with the highest incidence of SFTS. May to July was the peak of the epidemic, and farmers were a high-risk group. The risk factor for SFTS included age (poor prognosis) and tick bites (contracting SFTS). Patients with severe diarrhea and vomiting symptoms on admission should be noted. Clinicians could use routine laboratory parameters and clinical symptoms as references for clinically suspected cases, classification of SFTS, and timely treatment, especially in basic hospitals.

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease caused by severe fever with thrombocytopenia syndrome virus (SFTSV). SFTSV has been found in humans, ticks and animals, and SFTS has high mortality and increasing prevalence in East Asia. In the study, the samples (heart, liver, lung, kidney, spleen, brain tissue and serum) were collected from 374 domestic animals and 241 wild animals in Pingqiao District and Xinxian County of Xinyang in Henan Province, China. 275 (44.72%, 275/615) animals were positive for anti-SFTSV antibodies, the anti-SFTSV antibodies positive ratios of domestic and wild animals were 43.58% (163/374) and 46.47% (112/241), respectively. There was no significant difference in domestic and wild animals, but significant differences were detected among different species of animals (χ2 = 112.59, P < 0.0001). Among 615 animals, 105 (17.07%, 105/615) animals were positive for SFTSV RNA, and only one SFTSV strain was isolated from heart tissue of a yellow weasel. The phylogenetic analysis shows that the sequence from animals belonged to the same group with viral sequences obtained from humans. The animals maybe play a reservoir host in maintaining the life cycle of SFTSV in nature.

Severe fever with thrombocytopenia syndrome (SFTS) is recognized as an emerging infectious disease. This study aimed to investigate the pathogenic mechanism of SFTS. A total of 100 subjects were randomly included in the study. Cytokine levels were detected by enzyme‐linked immunosorbent assay and the viral load was detected by micro drop digital PCR. The results showed that levels of interleukin‐6 (IL‐6), IL‐8, IL‐10, IFN‐inducible protein‐10 (IP‐10), monocyte chemoattractant protein‐1 (MCP‐1), macrophage inflammatory protein‐1α (MIP‐1α), transforming growth factor‐β1 (TGF‐β1), and regulated upon activation normal T cell expressed and secreted factor (RANTES) differed significantly among the SFTS patient group, healthy people group, and asymptomatic infection group (p < .05). Compared to the healthy people group, the patient group had increased cytokine levels (IL‐6, IL‐10, IP‐10, MCP‐1, and IFN‐γ) but reduced levels of IL‐8, TGF‐β1, and RANTES (p < .0167). IL‐6, IL‐8, IL‐10, IP‐10, MCP‐1, MIP‐1α, TGF‐β1, and the RANTES levels had different trends after the onset of the disease. IL‐6, IL‐10, IP‐10, and MCP‐1 levels in severe patients were higher than those in mild patients (p < .05). There was a positive correlation between viral load and IL‐6 and IP‐10 but a negative correlation between viral load and RANTES. SFTSV could cause a cytokine change: the cytokine levels of patients had different degrees of fluctuation after the onset of the disease. The levels of IL‐6 and IL‐8 in the asymptomatic infection group were found between the SFTS patients group and the healthy people group. The levels of IL‐6, IL‐10, IP‐10, and MCP‐1 in the serum could reflect the severity of the disease, and the levels of IL‐6, IP‐10, and RANTES were correlated with the viral load.

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging disease that was first reported in China in 2011. It is caused by SFTS virus (SFTSV) which is a member of the Phlebovirus genus in the Bunyaviridae family. SFTSV has been classified as a BSL3 pathogen. There is a need to develop safe and affordable serodiagnostic methods for proper clinical management of infected patients. The full length nucleocapsid (N) gene of SFTSV Yamaguchi strain was amplified by RT-PCR and cloned to an expression vector pQE30. The recombinant (r) SFTSV-N protein was expressed by using Escherichia coli (E. coli) expression system and purified under native conditions. rSFTSV-N protein based indirect IgG and IgM enzyme linked immunosorbent assay (ELISA) systems were established to detect specific human IgG and IgM antibodies, respectively. One hundred fifteen serum samples from clinically suspected-SFTS patients were used to evaluate the newly established systems and the results were compared with the total antibody detecting sandwich ELISA system. The native form of recombinant (r) SFTSV-N protein was expressed and purified. Application of the rSFTSV-N protein based indirect IgG ELISA to the 115 serum samples showed results that perfectly matched those of the total antibody sandwich ELISA with a sensitivity and specificity of 100 %. The rSFTSV-N protein based indirect IgM ELISA missed 8 positive samples that were detected by the total antibody sandwich ELISA. The sensitivity and specificity of rSFTSV-N-IgM capture ELISA were 90.59 and 100 %, respectively. The rSFTSV-N protein is highly immunoreactive and a good target for use as an assay antigen in laboratory diagnosis. Its preparation is simpler in comparison with that used for the total antibody sandwich system. Our rSFTSV-N protein-based IgG and IgM ELISA systems have the advantage of distinguishing two types of antibodies and require small volume of serum sample only. They are safe to use for diagnosis of SFTS virus infection and especially fit in large-scale epidemiological investigations.

Human noroviruses are a major cause of viral gastroenteritis and are the main etiological agents of acute gastroenteritis outbreaks. An increasing number of outbreaks and sporadic cases of norovirus have been reported in China in recent years. There was a large acute gastroenteritis outbreak at a university in Henan Province, China in the past five years. We want to identify the source, transmission routes of the outbreak by epidemiological investigation and laboratory testing in order to provide the effective control measures. The clinical cases were investigated, and analysed by descriptive epidemiological methods according to factors such as time, department, grade and so on. Samples were collected from clinical cases, healthy persons, the environment, water, and food at the university. These samples were tested for potential bacteria and viruses. The samples that tested positive for norovirus were selected for whole genome sequencing and the sequences were then analysed. From 4 March to 3 April 2015, a total of 753 acute diarrhoea cases were reported at the university; the attack rate was 3.29%. The epidemic curve showed two peaks, with the main peak occurring between 10 and 20 March, accounting for 85.26% of reported cases. The rates of norovirus detection in samples from confirmed cases, people without symptoms, and environmental samples were 32.72%, 17.39%, and 9.17%, respectively. The phylogenetic analysis showed that the norovirus belonged to the genotype GII.17. This is the largest and most severe outbreak caused by genotype GII.17 norovirus in recent years in China. The GII.17 viruses displayed high epidemic activity and have become a dominant strain in China since the winter of 2014, having replaced the previously dominant GII.4 Sydney 2012 strain.

Severe fever with thrombocytopenia syndrome (SFTS) is a disease with a high case-fatality rate that is caused by infection with the SFTS virus (SFTSV). Five electronic databases were systematically searched to identify relevant articles published from 1 January 2011 to 1 December 2019. The pooled rates with 95% confidence interval (CI) were calculated by a fixed-effect or random-effect model analysis. The results showed that 92 articles were included in this meta-analysis. For the confirmed SFTS cases, the case-fatality rate was 0.15 (95% CI 0.11, 0.18). Two hundred and ninety-six of 1384 SFTS patients indicated that they had been bitten by ticks and the biting rate was 0.21 (95% CI 0.16, 0.26). The overall pooled seroprevalence of SFTSV antibodies among the healthy population was 0.04 (95% CI 0.03, 0.05). For the overall seroprevalence of SFTSV in animals, the seroprevalence of SFTSV was 0.25 (95% CI 0.20, 0.29). The infection rate of SFTSV in ticks was 0.08 (95% CI 0.05, 0.11). In conclusion, ticks can serve as transmitting vectors of SFTSVs and reservoir hosts. Animals can be infected by tick bites, and as a reservoir host, SFTSV circulates continuously between animals and ticks in nature. Humans are infected by tick bites and direct contact with patient secretions.