Epidemiological characteristics of patients with severe fever with thrombocytopenia syndrome in Dongyang City / 预防医学

Objective @#To investigate the epidemiological characteristics of severe fever with thrombocytopenia syndrome (SFTS) in Dongyang City, Zhejiang Province from 2017 to 2022, so as to provide insights into SFTS prevention and control. @*Methods@#Data pertaining to patients with SFTS in Dongyang City from 2017 to 2022 were collected from Notifiable Infectious Disease Reporting System of Chinese Disease Prevention and Control Information System. The epidemiological and clinical characteristics of patients with SFTS were descriptively analyzed, and the trends in incidence of SFTS was evaluated using annual percent change (APC). @*Results@#A total of 32 SFTS cases were reported in Dongyang City from 2017 to 2022, with mean annual incidence of 0.63/105, and 8 cases died, with a fatality rate of 25.00%. The incidence of SFTS appeared a tendency towards a rise from 2017 to 2022 (APC=40.697%, P<0.05). The male to female ratio of SFTS cases was 0.78∶1, and farmer was the predominant occupation (31 cases, 96.88%). SFTS predominantly occurred among individuals at ages of 51 to 69 years (20 cases, 62.50%), and the incidence peaked during the period between March and May and between July and August (28 cases, 87.50%). SFTS cases were reported in 11 out of the 18 townships (streets) in Dongyang City, with the highest number found in Zuocun Township (8 cases, 28.13%), and had the lowest platelet count of (41.46±5.19)×109 platelets/L, with the lowest count of (3.00 to 67.00) ×109 platelets/L. All the SFTS cases had a history of mountain forest and farmland activities 2 weeks prior to onset of the disease, and 5 cases (15.63%) had a history of tick bites.@*Conclusions@#The incidence of SFTS appeared a tendency towards a rise in Dongyang City from 2017 to 2022, and SFTS was highly prevalent in spring and summer, with high incidence among farmers. Intensified health education of SFTS is recommended among residents in high-incidence areas.

Expression of Gn protein of severe fever with thrombocytopenia syndrome virus and its immunogenicity / 中国生物制品学杂志

@#Objective To express the Gn protein of severe fever with thrombocytopenia syndrome virus(SFTSV) through adeno-associated virus 9(AAV9) expression system and evaluate its immunogenicity.Methods SFTSV Gn gene was inserted into viral vector pAAV-CMV-FH and the recombinant plasmid was transfected into HEK293T cells to obtain recombinant virus AAV9-Gn.The expression of Gn protein was determined by immunofluorescence and Western blot.Eighteen fernale BALB/c mice were randomly divided into three groups:Mock group(serum-free DMEM),AAV9-GFP group(1 × 10~(11) vg) and AAV9-Gn group(1 × 10~(11) vg),all of which were injected intramuscularly into the right hind limb at a dose of 100 μL per mouse.The body mass,diet,behavior and mental state of mice in each group were monitored continuously for 21 d,and the change rate of body mass was calculated;At 2,4,8 and 16 weeks after immunization,the levels of SFTSV neutralizing antibody in serum of mice in each group were detected by fluorescent reduction neutralization test(FRNT),and the levels of specific IgGl and IgG2a in serum of mice in AAV9-Gn group were detected by ELISA.Results After incubation with specific antibody,Vero cells transfected with AAV9-Gn showed specific green fluorescence under fluorescence microscope,and had specific binding to mouse anti-SFTSV Gn monoclonal antibody,and the specific binding bands were found at a relative molecular mass of about 61 000.The body mass of the three groups showed an increasing trend,there was no significant difference between the three groups(F=0.158—2.621,P> 0.05),and the diet,behavior and mental state were normal.At 2,4,8 and 16 weeks after immunization,the titer of SFTSV neutralizing antibody in serum of mice in AAV9-Gn group was significantly higher than that of Mock group and AAV9-GFP group(H=13.332—14.538,each P <0.001),and the titer peak appeared at 8 weeks;The level of specific IgG1 in serum of mice was significantly higher than that of IgG2a(F=4.373—12.975,each P <0.05) at different time points.Conclusion SFTSV Gn protein can be expressed correctly through AAV9 expression system,and has low toxicity to mice with good immunogenicity,which is expected to be a candidate component of SFTSV vaccine.

Epidemiological investigation and genomic characterization of the first case of fever with thrombocytopenia syndrome in Puyang / 中华微生物学和免疫学杂志

Objective:To report the first case of sever fever with thrombocytopenia syndrome caused by severe fever with thrombocytopenia syndrome virus (SFTSV) in Puyang city, and to study the epidemiological and molecular characteristics of S, M, L fragments of the SFTSV isolate.Methods:The epidemiological characteristics of this case was analyzed with epidemiological methods. SFTSV was isolated from the patient′s serum sample. Nucleic acid of SFTSV was extracted and detected by fluorescent RT-PCR. A multiplex PCR method was constructed to amplify the nucleic acid sequence of the virus. whole-genome sequencing was performed on the next-generation sequencing platform. MEGA11 and DNAStar was used for homology analysis and a phylogenetic tree was constructed.Results:Epidemiological investigation showed that the patient and his close contacts had no history of travel or tick bite within 14 d, but had a history of fieldwork. The patient′s serum sample was positive for SFTSV nucleic acid. Genetic analysis showed that the S, M, L gene fragments of the first SFTSV isolate in Puyang belonged to genotype E. This isolate shared 94.8%-99.6%, 94.0%-99.8% and 95.7%-99.7% nucleotide sequence homology with the representative strains acquired from GeneBank in S, M, L gene fragments, respectively.Conclusions:This case was the first case of SFTSV-caused severe fever with thrombocytopenia syndrome in Puyang. The SFTSV isolate shared a close homology with domestic isolates, but its genotype was significantly different from the SFTSV strains isolated in Henan in recent years, indicating that it might an imported case from other places in Henan Province or Hubei Province. Disease monitoring and professional training for medical personnel should be strengthened and more attention should be paid to the evolution and mutation of SFTSV.

Construction of a model for early identification of spotted fever and severe fever with thrombocytopenia syndrome / 预防医学

Objective@#To construct a model for clinical identification of spotted fever (SF) and severe fever with thrombocytopenia syndrome (SFTS), so as to provide insights into early identification of SF and SFTS.@*Methods@#The clinical data of laboratory-confirmed SF and SFTS patients in secondary and tertiary hospitals in Lu'an City, Anhui Province from May 2017 to May 2021 were retrieved from Chinese Disease Prevention and Control Information System. Factors affecting SF were identified using a logistic regression model, and the model for early identification of SF and SFTS was created. The model fitting effect was evaluated using Hosmer-Lemeshow test, and the value of the model for identification of SF and SFTS was evaluated using the area under the receiver operating characteristic curve (AUC).@*Results@#Data of 62 SF cases and 115 SFTS cases were included. Multivariable logistic regression analysis showed that rash (β=5.994), C-reactive protein (β=4.409), white blood cell (β=-3.176) and platelet (β=-3.234) were included in the model, which were scored 6, 4, -3 and -3, with a total score ranging from -5 to 10. Hosmer-Lemeshow test revealed a high model fitting effect (χ2=3.245, P=0.662). The AUC of the model was 0.992, and the sensitivity and specificity were 0.935 and 0.991 if the cutoff was 1.@*Conclusion@#A model for early identification of SF and SFTS that includes four variables of rash, C-reactive protein, white blood cell and platelet has been created, which has a high accuracy.

A case of severe fever with thrombocytopenia syndrome with Campylobacter jejuni bacteremia / 中国热带医学

@#Abstract: Objective　 This article aims to present a rare case of severe fever with thrombocytopenia syndrome (SFTS) complicated by with bacteraemia caused by Campylobacter jejuni, and to discuss the pathogenic characteristics, culture methods, clinical features and treatment points of Campylobacter jejuni and the patient's outcome, with a view to raising clinical awareness of blood culture and providing experience for the treatment of this disease. Methods　The clinical data of a case with SFTS complicated by bacteremia caused by Campylobacter jejuni admitted to Weihai Municipal Hospital were collected and the diagnostic process of the pathogenic bacteria as well as the treatment plan were retrospectively analysed. Results　The patient was a female who had been bitten by a tick bite half a month ago and presented to the hospital on 30th August with a fever, vague pain in the peribulbar abdomen and diarrhea for 5 days. Laboratory tests showed leukopenia and thrombocytopenia, and nucleic acid detection for SFTS was positive, resulting in a diagnosis of SFTS. After a week of antiviral treatment with ribavirin and symptomatic treatment, the patient suddenly experienced high fever at night, with a temperature reaching 39.5 °C. Blood cultures were immediately taken from both sides of the double bottle. Bilateral anaerobic bottles were tested for positive after 53.06 hours, and Gram-negative Campylobacter was cultured anaerobically in a transfer blood plate and further identified as Campylobacter jejuni using mass spectrometry MALDI-TOF MS. Vancomycin was stopped clinically on the basis of bacterial pathogenesis and meropenem was used for anti-infection and symptomatic treatment. During the treatment, blood culture and nucleic acid detection for SFTS turned negative, and the patient's symptoms improved. After normal results were achieved in the follow-up testing, the patient was discharged. Conclusions　This case serves as a reminder that Campylobacter jejuni not only causes intestinal infections, but can also lead to extra-intestinal infections in immunocompromised individuals. Clinical and laboratory personnel should increase their recognition of Campylobacter jejuni, prioritize blood culture methods, and utilize a multidisciplinary approach in diagnosis and treatment.

A comparative study of the clinical characteristics of spotted fever and severe fever with thrombocytopenia syndrome / 中国热带医学

@#Abstract: Objective To investigate the differences in epidemiological and clinical characteristics of patients with spotted fever (SF) and severe fever with thrombocytopenia syndrome (SFTS). Methods A total of 86 patients with SF and 113 patients with SFTS who were laboratory-confirmed in the second-level and above hospitals in Lu'an City from January 2017 to January 2022 were selected. The basic data, epidemiological history, clinical data and laboratory test results of the two diseases were retrospectively analyzed for comparison. Results The proportion of male in SF group was 32.56% (28/86), and the proportion of male in SFTS group was 53.98% (61/113), the difference was statistically significant (χ2=9.067, P<0.01). The proportions of abdominal pain and diarrhea in the SF group were (3.49%, 3/83) and (21.24%, 24/113), which were significantly lower than corresponding (6.98%, 6/86) and (46.90%, 53/113) in the SFTS group (χ2=13.121, 37.322, P<0.01). The incidences of rash and eschar in SF group were 95.35% (82/86) and 20.93% (18/86), which were significantly higher than corresponding 1.77% (2/113) and 0.88% (1/113) in SFTS group (χ2=175.311, 22.721, P<0.01). The levels of leukocytes, platelets and C-reactive protein in the SF group were significantly higher than those in the SFTS group, and the levels of transaminase, lactate dehydrogenase and D-dimer were significantly lower than those in the SFTS group, and the differences were statistically significant (all P<0.05). Conclusions The rash and inflammatory reaction are more obvious in SF patients, while the liver function, myocardial function and coagulation function are significantly impaired in SFTS patients.

Analysis of microbial diversity in the midgut of Haemaphysalis longicornis infected with severe fever with thrombocytopenia syndrome virus / 中国热带医学

@#Abstract: Objective　To investigate the composition and diversity of midgut microbial community of Haemaphysalis longicornis infected with severe fever with thrombocytopenia syndrome virus (SFTSV)． Methods　The midgut DNA of three group Haemaphysalis longicornis infected with SFTSV was extracted, and the 16S rDNA gene of the sample was sequenced by HiSeq platform. The composition and diversity of endosymbiotic microbial community were clarified by OTU cluster analysis and alpha diversity analysis. Results　The midgut microbial clusters of the three groups infected with SFTSV were 143, 113, 163 OTUs respectively; the sparsity curve and abundance grade curve showed that the data had sufficient sequencing depth, and the midgut of Haemaphysalis longicornis infected with SFTSV was rich in microbial composition, but the species distribution was uneven. The analysis of microbial community composition showed that Proteobacteria, Firmicutes and Actinobacteria were the main dominant bacteria at the phyla level. At the class level, Gammaproteobacteria, Bacilli, Betaproteobacteria and Actinomycetia were the main dominant bacteria. At the order level, Legionellales, Bacillales, Burkholderiales and Actinomycetales were the main dominant orders. At the family level, Coxiellaceae, Bacillaceae, Moraxellaceae and Rhodococcaceae were the main dominant families. At the genus level, the relative abundance of Coxiella was the highest, followed by Aeribaillus and Azonexus. Alpha diversity analysis showed that the average Shannon index was 139.67, the average Simpson index was 0.48, the average Chao index was 145.06, and the average ACE index was 147.11. Conclusions　The species diversity of intestinal microorganisms in Haemaphysalis longicornis infected with SFTSV is rich. The results provide a basis for further exploring the interaction between intestinal microbes of Haemaphysalis longicornis and SFTSV and developing new ideas for the prevention and control of ticks and tick-borne diseases.

Establishment and evaluation of a genome-wide multiplex PCR sequencing method for severe fever with thrombocytopenia syndrome virus based on high-throughput sequencing technology / 中华微生物学和免疫学杂志

Objective:To establish a sequencing method for the genome of severe fever with thrombocytopenia syndrome virus (SFTSV) based on next-generation sequencing (NGS).Methods:SFTSV RNA was extracted from serum samples of patients with severe fever with thrombocytopenia syndrome. SFTSV-specific primers were designed using Primer 5.0 software. A multiplex PCR method was constructed and used to amplify the nucleotide sequence of SFTSV. Whole-genome sequencing was performed on the NGS platform.Results:The whole genes of SFTSV isolates in 28 serum samples were amplified by the multiplex PCR with a coverage over 94%. Sequencing and phylogenetic analysis of those strains revealed that the predominant strains ( n=20) belonged to genotype A, followed by genotypes B ( n=4) and E ( n=3). Conclusions:A high-throughput sequencing method for SFTSV based on multiplex PCR was established in this study. This method was characterized by high specificity and good quality and could improve the sequencing efficiency.

Expert consensus on diagnosis and treatment of severe fever with thrombocytopenia syndrome / 中华临床感染病杂志

Since 2010, the incidence of severe fever with thrombocytopenia syndrome (SFTS) has been increased. Owing the progress in diagnosis and treatment, the overall mortality of SFTS in China has decreased, while the mortality in critical SFTS patients is still high. In order to provide guidance and working procedures for clinicians to diagnose and treat critical SFTS, the National Medical Center for Major Public Health Events invited experts to discuss and formulate this consensus based on their experience and up-to-date knowledge on SFTS.

Epidemiological characteristics of severe fever with thrombocytopenia syndrome and association with tick density / 上海预防医学

ObjectiveTo understand the epidemiological characteristics of severe fever with thrombocytopenia syndrome （SFTS）， and the association with seasonal fluctuation in tick density， so as to provide scientific evidence for better control and prevention measures. MethodsDescriptive epidemiological methods were used to analyze the SFTS epidemic situation in Chongyang County from 2013 to 2021. The cloth flag method was used to investigate the seasonal fluctuation in tick density and determine the association with the SFTS. ResultsA total of 71 SFTS cases were reported in Chongyang County from 2013 to 2021 including 8 deaths， with the annual morbidity rate of 1.88/10-5. The majority were mainly from June to August， accounting for 61.97% of the total reported cases. The cases were geographically distributed in 41 administrative villages and 4 urban areas in 11 towns. The highest incidence was in Lukou town （n=26） and Baini town （n=12）， which accounted for 53.52% of the total reported cases. Furthermore， the cases were mainly 50‒69 years old， accounting for 57.75% of the total reported cases. The ratio of male to female was 1.84∶1， and most were farmers. Blood samples during acute phase in 41 cases were collected for examination of SFTS virus， of which 25 cases tested positive （60.98%）. There was a positive association between tick density and the number of reported SFTS cases （r=0.78， P=0.003）. ConclusionSeasonal density of free adult ticks and nymphs is associated with the number of reported SFTS cases in Chongyang County.

Development of monoclonal antibody based IgG and IgM ELISA for diagnosis of severe fever with thrombocytopenia syndrome virus infection

ABSTRACT Introduction: Severe fever with thrombocytopenia syndrome virus (SFTSV) is a newly emerged virus that poses a great threat to human health because of high fatality rate. Methods: To develop sensitive and specific sero-diagnostic systems for SFTSV infections, monoclonal antibodies (MAbs) against recombinant SFTSV nucleocapsid (rSFTSV-N) protein were developed by immunizing BALB/C mice with rSFTSV-N protein and fusing the spleen cells with SP2/0 myeloma cells. Three hybridoma cell lines secreting MAbs against rSFTSV-N were obtained. MAb based IgG sandwich enzyme linked immunosorbent assay (ELISA) and IgM capture ELISA systems were established by using the newly developed MAbs. One hundred fifteen clinical suspected SFTS patients serum samples were used to evaluate the newly established systems by comparing with the total antibody detecting sandwich ELISA system and indirect ELISA systems. Results: The MAbs based sandwich IgG ELISA was perfectly matched with that of the total antibody sandwich ELISA and the indirect IgG ELISA. IgM capture ELISA results perfectly matched with that of the total antibody sandwich ELISA while detecting eight additional positive samples missed by the indirect IgM ELISA. Conclusions: The MAbs against rSFTSV-N protein offer new tools for SFTSV studies and our newly developed MAb-based IgG and IgM capture ELISA systems would offer safe and useful tools for diagnosis of SFTS virus infections and epidemiological investigations.

Analysis of epidemiological characteristics of severe fever with thrombocytopenia syndrome in Yiyuan of Shandong Province，from 2014 to 2019 / 上海预防医学

ObjectiveTo understand the epidemiological characteristics of severe fever with thrombocytopenia syndrome （SFTS） in Yiyuan County， and provide scientific evidence for prevention and control strategies. MethodsDescriptive epidemiological methods were used to analyze the incidence of SFTS in Yiyuan County during 2014—2019. ResultsA total of 130 SFTS cases were documented in Yiyuan County during 2014—2019， of which four were death cases. The annual incidence was determined to be 3.79/105 and the mortality was 3.08%， showing an upward trend in the incidence （ χ T r e n d 2 =9.06， P=0.003）. Majority of the cases occurred between May and August （88.46%）， were more than 50 years old （81.54%）， and farmers （94.62%）. The median duration of time from onset to diagnosis was five days. ConclusionSFTS was widely distributed in Yiyuan County with seasonal pattern. Middle aged and elderly farmers were mainly susceptible. It warrants strengthening prevention and control of SFTS and health education in elderly.

Analysis of epidemiological characteristics of severe fever with thrombocytopenia syndrome in Yiyuan of Shandong Province，from 2014 to 2019 / 上海预防医学

ObjectiveTo understand the epidemiological characteristics of severe fever with thrombocytopenia syndrome （SFTS） in Yiyuan County， and provide scientific evidence for prevention and control strategies. MethodsDescriptive epidemiological methods were used to analyze the incidence of SFTS in Yiyuan County during 2014—2019. ResultsA total of 130 SFTS cases were documented in Yiyuan County during 2014—2019， of which four were death cases. The annual incidence was determined to be 3.79/105 and the mortality was 3.08%， showing an upward trend in the incidence （ χ T r e n d 2 =9.06， P=0.003）. Majority of the cases occurred between May and August （88.46%）， were more than 50 years old （81.54%）， and farmers （94.62%）. The median duration of time from onset to diagnosis was five days. ConclusionSFTS was widely distributed in Yiyuan County with seasonal pattern. Middle aged and elderly farmers were mainly susceptible. It warrants strengthening prevention and control of SFTS and health education in elderly.

Analysis of three family clusters of severe fever with thrombocytopenia syndrome by exposure risk matrix / 预防医学

Objective@#To analyze three events of severe fever with thrombocytopenia syndrome （SFTS） among family members by exposure risk matrix, so as to provide reference for SFTS prevention and control.@*Methods @#The field investigation and clinical data of seven confirmed cases with SFTS reported in Linhai from 2014 to 2016 were collected. Exposure risk matrix was used to list the risk of exposure two weeks before the onset, such as the environment, duration of activity and protection, and evaluate the possible routes of transmission. @*Results@#The first event involved three sisters. Two of them had plucked tea together on a hill, and the possibility of infection through tick bites were 60% and 75%, respectively. Another sister was more likely to be infected by ticks in her residence after visiting her sister （no physical contact with the sick sister）, with a possibility of 74%. The second event involved two cases （mother and son）. They were more likely to be infected by ticks in the current residential area, and the possibility were 100% and 80%, respectively. The third event involved two cases （husband and wife）. The wife had 60% possibility of being infected by the ticks on the hill she picked arbutus, and 40% by the ticks in her residence. The husband was most likely to be infected through contacting with body fluids or blood of his wife （44%）, then through the ticks on the hill he picked arbutus （33%）. @*Conclusion@#Among seven cases with SFTS reported in Linhai from 2014 to 2016, six cases have more than 50% possibility of being infected by tick bites; one case has higher possibility of being infected by contacting with body fluids or blood of a patient, but tick bites could not be ruled out.

Clinical Score System to Differentiate Severe Fever with Thrombocytopenia Syndrome Patients from Patients with Scrub Typhus or Hemorrhagic Fever with Renal Syndrome in Korea

BACKGROUND: Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease with high mortality in East Asia. This study aimed to develop, for primary care providers, a prediction score using initial symptoms and basic laboratory blood tests to differentiate between SFTS and other endemic zoonoses in Korea.METHODS: Patients aged ≥ 18 years diagnosed with endemic zoonoses during a 3-year period (between January 2015 and December 2017) were retrospectively enrolled from 4 tertiary university hospitals. A prediction score was built based on multivariate logistic regression analyses.RESULTS: Of 84 patients, 35 with SFTS and 49 with other endemic zoonoses were enrolled. In multivariate logistic regression analysis, independent predictors of SFTS included neurologic symptoms (odds ratio [OR], 12.915; 95% confidence interval [CI], 2.173–76.747), diarrhea (OR, 10.306; 95% CI, 1.588–66.895), leukopenia (< 4,000/mm3) (OR, 19.400; 95% CI, 3.290–114.408), and normal C-reactive protein (< 0.5 mg/dL) (OR, 24.739; 95% CI, 1.812–337.742). We set up a prediction score by assigning one point to each of these four predictors. A score of ≥ 2 had 82.9% sensitivity (95% CI, 71.7%–87.5%) and 95.9% specificity (95% CI, 88.0%–99.2%). The area under the curve of the clinical prediction score was 0.950 (95% CI, 0.903–0.997).CONCLUSION: This study finding suggests a simple and useful scoring system to predict SFTS in patients with endemic zoonoses. We expect this strategic approach to facilitate early differentiation of SFTS from other endemic zoonoses, especially by primary care providers, and to improve the clinical outcomes.

Vector biological monitoring and strategy to prevent and control severe fever with thrombocytopenia syndrome bunyavirus (SFTSV) in Daishan Country Zhoushan Islands 2011-2018 / 上海预防医学

Objective To study the severe fever with thrombocytopenia syndrome bunyavirus (SFTSV)-related vector biological monitoring in Daishan County, Zhoushan Island of Zhejiang Province, and to explore the prevention and control strategies. Methods The monitoring was conducted as follows:squirrel-cage method was used for rodents from 2012 to 2014;the Buqi method for free tick density in villages and towns with confirmed cases in Daishan County from 2015 to 2018;and body surface comb method for parasitic ticks.RT-PCR method was used to detect SFTSV in ticks and rat specimens.Epidemiological survey followed by extensive health education was conducted from 2011 to 2015.Comprehensive health prevention and control measures, such as precision health education and chemical elimination of vectors were taken from 2016 to 2018. Results A total of 327 rodents were captured, including 172 stinking shrews, accounting for 52.60%, and 92 yellow mice, accounting for 28.13%.The main species of ticks was Haematopsus longicortus, accounting for 94.20%.Among them, there were 135 parasitic ticks in three species:Haematopsus longicorum, S.scallopus, and T.nigra. There were 382 free ticks in 6 species, including Haematopsichum longicorum, Sickle fan tick, Hemophilus fannicus, Ixodes ovaliformis, Ixodes granulata, and Ixodes sinensis.From May to October in 2015, the density of field ticks was ≥50 per cloth flag.From May 2016 to 2018, after the elimination application of chemical agents for elimination, the density of ticks was ≤50 per cloth flag.All ticks and rodent specimens tested by RT-PCR were negative for SFTSV.Since precision education in 2016, the awareness rate of SFTS in rural areas has increased from 32.05% to 83.33%.Approximately 70 early warning notices for the epidemic situation were issued in advance.Since 2017, the number of SFTS has been declining year by year, and only 8 cases occurred in 2018. Conclusion In the field environment, chlorothalonil is the dominant mouse species and long horn blood ticks are the dominant ticks.The government leadership, cooperation among departments, technical service provided by professional organization, health education, reduction of tick density in residential environment, timely risk early warning notice, and other comprehensive prevention and control hand strategy all contribute to the achieved result of prevention and control.

Co-Infection of Scrub Typhus and Human Granulocytic Anaplasmosis in Korea, 2006

BACKGROUND: Scrub typhus, severe fever with thrombocytopenia syndrome (SFTS) and human granulocytic anaplasmosis (HGA) are important arthropod-borne infectious diseases in Korea and share a common point that they are transmitted by arthropod bites mostly during outdoor activities and there are considerable overlaps of epidemiologic and clinical features at presentation. We investigated the co-infection of these infections. METHODS: The study subjects were patients with laboratory-confirmed scrub typhus who were enrolled retrospectively in 2006. SFTS virus (SFTSV) infection was confirmed by a reverse transcriptase polymerase chain reaction (PCR) to amplify partial L segment of SFTSV for molecular diagnosis. HGA was confirmed by a nested PCR to amplify 16S rRNA gene of Anaplasma phagocytophilum. Direct sequencing of the positive PCR products was performed. Clinical features of co-infected subjects were described. RESULTS: One-hundred sixty-seven patients with scrub typhus were included in the analysis. Co-infection of A. phagocytophilum was identified in 4.2% of scrub typhus patients (7/167). The route of co-infection was uncertain. The co-infected patients had not different clinical manifestations compared to the patients with scrub typhus only. All the study subjects were negative for SFTSV. CONCLUSION: We found retrospective molecular evidence of the co-infection of scrub typhus and HGA in Korea. HGA may be more prevalent than expected and need to be considered as an important differential diagnosis of febrile patients in Korea.

Four Year Surveillance of the Vector Hard Ticks for SFTS, Ganghwa-do, Republic of Korea

The seasonal abundance of hard ticks that transmit severe fever with thrombocytopenia syndrome virus was monitored with a collection trap method every April to November during 2015–2018 and with a flagging method every July and August during 2015–2018 in Ganghwa-do (island) of Incheon Metropolitan City, Republic of Korea. This monitoring was performed in a copse, a short grass field, coniferous forest and broad-leaved forest. A total of 17,457 ticks (8,277 larvae, 4,137 nymphs, 3,389 females, and 1,654 males) of the ixodid ticks comprising 3 species (Haemaphysalis longicornis, H. flava, and Ixodes nipponensis) were collected with collection traps. Of the identified ticks, H. longicornis was the most frequently collected ticks (except larval ticks) (94.26%, 8,653/9,180 ticks (nymphs and adults)), followed by H. flava (5.71%, 524/9,180) and Ix. nipponensis (less than 0.04%, 3/9,180). The ticks collected with collecting traps were pooled and assayed for the presence of SFTS virus with negative results. In addition, for monitoring the prevalence of hard ticks, a total of 7,461 ticks (5,529 larvae, 1,272 nymphs, 469 females, and 191 males) of the ixodid ticks comprising 3 species (H. longicornis, H. flava, and Ix. nipponensis) were collected with flagging method. H. longicornis was the highest collected ticks (except larval ticks) (99.53%, 1,908/1,917 ticks (nymphs and adults)), followed by H. flava (1.15%, 22/1,917).

Effects of severe fever with thrombocytopenia syndrome virus infection on the expression of TLR2 and inflammatory cytokines in mouse peritoneal macrophages / 医学研究生学报

Objective The secretion level of inflammatory factors is closely related to the severity of severe fever with thrombocytopenia syndrome (SFTS). This paper mainly discussed the effect of SFTSV infection on the expression of Toll-like receptor 2（TLR2） and inflammatory factors in macrophages in mice. Methods The expression of TLR2 andTNF-α, IFN-β, IL-6, IL-10 and other inflammatory factors were observed at 0, 6, 12, 24, 36, 48, 72 hours after SFTSV infected mice macrophages by qPCR, Western blot and ELISA. Results QPCR results showed that the mRNA levels of TNF-α at 0, 6, 12, 24, 36, 48, 72 h were 0.85±0.14, 15.23±2.45, 28.67±1.59, 94.52±7.05, 55.86±1.82, 23.55±6.15, 9.76±2.03, and the mRNA levels of IFN-β were 0.93±0.21, 1.55±0.33, 14.51±1.98, 55.16±3.64, 26.57±1.49, 9.22±0.51, 5.18±1.06. QPCR results showed that the mRNA levels of TNF-α and IFN-β produced by abdominal macrophages in the infected mice showed a trend of first increasing (the highest at the 24 hour) and then decreasing, and the difference of TNF-α and IFN-β mRNA levels at other time points was statistically significant compared with that at the 0 hour (P<0.05). However, IL-6 and IL-10 mRNA levels continued to increase, and the difference at other time points was statistically significant (P<0.05). ELISA results showed that the expression of four inflammatory factors showed a trend of gradual increase: TNF-α 0 and 72 h were (38.31±4.25, 140.41±23.45) pg/mL; IFN-β 0th and 72th were (17.56±0.66, 1084.93±111.42) pg/mL; IL-6 protein 0 and 72 h were (113.30±0.07, 2302.32±134.09) pg/mL; IL-10 protein 0 and 72 h were (515.00±21.21, 2590.40±226.19) pg/mL, respectively, with significant increases at the 24, 36, 48 and 72 hours compared with that at the 0 hour (P<0.05). The expression of TLR2 mRNA generated by mouse peritoneal macrophages showed a trend of first increasing and then decreasing, and increased to the highest level at 24 h, and the difference between each time point and 0 h was statistically significant (P<0.01). The expression of TLR2 gradually increased after infection with time extension. Conclusion SFTSV infection can up-regulate the expression of TLR2 in macrophages, thereby leading to the increased secretion of the cytokines.

Analysis on the epidemiology and etiologic characteristics of first imported severe fever with thrombocytopenia syndrome case in Shenzhen / 中华实验和临床病毒学杂志

Objective@#To study the epidemiology and the etiology characteristics of first imported severe fever with thrombocytopenia syndrome (SFTS) case reported in Shenzhen city in 2017.@*Methods@#Data on descriptive epidemiology was collected to study the characteristics to the epidemic. The serum sample collected from the suspect SFTS case was detected for IgM, IgG by ELISA and severe fever with thrombocytopenia syndrome bunyavirus (SFTSV) nucleic acid by real-time RT-PCR. The samples were further inoculated in Vero cell for virus isolation. The partial fragements of L and S gene were amplified by RT-PCR and sequenced to construct homology comparison and phylogenetic tree with the strains isolated from other areas.@*Results@#The case was laboratory confirmed imported SFTS case in Shenzhen on May 2017. IgM antibody and RNA of SFTSV were detected in the serum sample. SFTSV named GDSZ01/2017/China was successfully isolated from the serum sample. The high nucleotide homology of L and S genome segments were found at 95.3%-98.2% and 93.8%-98.8% with other representative strains from the popular provinces, respectively. The phylogenetic tree indicated that GDSZ01 was most close to SDTA_3 strain, next to strains in Hubei procince. The isolated SFTSV belonged to genotype C3 with HB29, HB154.@*Conclusions@#The virological, serological and molecular features showed that the imported case of SFTS in 2017 was caused by SFTSV C3 genotype.