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.

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.

A Pediatric Case of Severe Fever with Thrombocytopenia Syndrome in Korea

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease and elderly people living in rural areas have the greatest risk of infection. We report the first pediatric case of SFTS in Korea and the clinical characteristics and disease progression in children. A 10-year-old child from Chonnam province visited the hospital with myalgia and a history of fever over the previous 8 days. Her father noticed a tick on her head and removed it before fever developed. Because the symptoms continued, her father consulted the community health center and SFTS virus was detected both from the tick (Haemaphysalis longicornis) and the patient's blood. On hospitalization, fever and severe myalgia were improved and no gastrointestinal and hemorrhagic symptoms were observed. The patient was successfully treated with a combination of steroids, IVIG, and ribavirin. In this report, a pediatric case of SFTS presents a mild clinical course but close attention must be paid to the screening of children with mild symptoms consisting of SFTS.

Clinical analysis of patients with severe fever with thrombocytopenia syndrome bunyavirus infection and hemorrhagic fever with renal syndrome / 中华传染病杂志

Objective To compare the differences of epidemiology, clinical characteristics, laboratory results and prognosis between patients with severe fever with thrombocytopenia syndrome bunyavirus (SFTSV) infection and those with hemorrhagic fever with renal syndrome (HFRS).Methods Medical records of 16 hospitalized cases with SFTSV infection and 28 hospitalized HFRS cases from January 2012 to June 2016 were reviewed in affiliated Yijishan Hospital of Wannan Medical College.In details, the comparative analysis of patients between the two groups were conducted in sex, age, occupation, onset season, contact history, underlying diseases, fever duration, oliguria, bleeding (including petechiae, ecchymoses, gum bleeding, bloody stool and hematuria), secondary infection, consciousness disturbance, dialysis treatment, length of hospital stay, laboratory results and prognosis.Continuous variables of normal, non-normal distribution data were compared using two-sample t test and rank sum test, respectively.Categorical variables were showed in rate and compared using chi-square test.Results The differences between the two groups in age (t=2.585), occupation (χ2=4.914), onset season (χ2=4.325) and contact history (χ2=9.617) were all statistically significant (all P<0.05).In SFTSV infection group, the mean fever duration was (8.81±3.17) d.There were 2 cases of oliguria, 10 cases of bleeding, 7 cases of secondary infection, 5 cases of consciousness disturbance.No patient received dialysis.The average length of hospital stay was (13.44±7.91) d.In HFRS group, the mean fever duration was (5.96±2.20) d.In addition, there were 24 cases of oliguria, 25 cases of bleeding, 9 cases of secondary infection, 3 cases of consciousness disorder.Twelve cases received dialysis treatment in this group.The average length of hospital stay was (18.04±15.75) d.Furthermore, there were significant differences between the two groups in fever duration (t=3.511), oliguria (χ2=22.578), bleeding (χ2=4.490) and dialysis (χ2=7.392) (all P<0.05).The significant differences were also found in white blood cell count, blood urea nitrogen, serum creatinine, albumin, amylase, lipase, creatine kinase, serum sodium, chloride, calcium, carbon dioxide combining power and blood glucose between the SFTSV infection group and HFRS group (all P<0.05).However, there was no significant difference in prognosis between the two groups (Z=1.574, P=0.115).Conclusions There are differences in epidemiological history, clinical manifestations and laboratory findings between the SFTSV infection group and HFRS group, which may help differential diagnosis and treatment of these two diseases.

Risk factors for mortality in patients with severe fever with thrombocytopenia syndrome / 中华传染病杂志

Objective To analyze the clinical features and risk factors for mortality of patients with severe fever with thrombocytopenia syndrome (SFTS) in Zhoushan, the eastern coastal of China with high incidence of severe fever with thrambocytopenia syndrome bunyavirus infection, to provide reference for reducing the mortality rate of SFTS.Methods Clinical data of 107 cases of SFTS from Zhoushan Hospital during June 2011 to June 2016 were retrospectively analyzed.According to the prognosis, patients were divided into survival group and death group.The clinical features and the laboratory results were analyzed with a case-control method to analyze the prognostic factors.Normal distribution data were compared with the independent t test.Kolmogorov-Smirnov Z test were used in data with skewness distribution.Categorical data were analyze by chi-square test.The related risk factors were analyzed with the receiver-operating characteristic (ROC) curve and multivariate unconditioned logistics regression analysis.Results Seventeen cases among 107 STFs patients died, yielding the mortality rate of 15.9%.The proportion of patients suffering from two or more underlying diseases, with disorders of consciousness, activated partial thromboplastin time (APTT), the level of creatine kinase (CK), lactate dehydrogenase (LDH) as well as sepsis-related or sequential organ failure assessment (SOFA) score in death group were all significantly higher than those in the survival group (all P73.45 s, SOFA scores >9 were the independent risk factors for mortality of SFTS (OR=6.947, 8.459 and 11.770, respectively, all P<0.05).Conclusion Ca2+, APTT and SOFA score are the independent risk factors for prognosis of SFTS, which provide reference for prognostic evaluation of SFTS.

Bone Marrow Suppression and Hemophagocytic Histiocytes Are Common Findings in Korean Severe Fever with Thrombocytopenia Syndrome Patients

The causes of cytopenia in patients with severe fever with thrombocytopenia syndrome (SFTS) are not fully understood until now. We reviewed the bone marrow (BM) findings of patients with SFTS to unravel the cause of the cytopenia. Three Korean SFTS were enrolled in this study. Thrombocytopenia, neutropenia, and anemia were detected in all three patients. Severe hypocellular marrow (overall cellularity <5%) and a decreased number of megakaryocytes were noted in one patient, and hypo-/normocellular marrow and an increased number of hemophagocytic histiocytes were observed in two patients. Megakaryocytes were relatively preserved in two patients. Although a limited number of cases are available, our observations suggest that both BM suppression and peripheral destruction or sequestration are causes of cytopenia of patients with SFTS. To the best of our knowledge, this is the first well documented pathologic evaluation of Korean SFTS.

Clinical characteristics and risk factors for mortality of patients with severe fever with thrombocytopenia syndrome / 中华传染病杂志

Objective To summarize the clinical and laboratory characteristics of patients with severe fever with thrombocytopenia syndrome (SFTS ) and to identify the related risk factors for mortality .Methods Clinical features and laboratory parameters were collected from 40 SFTS patients (7 deaths and 33 survivors) .Dynamic changes of laboratory data were compared between the two groups , including white blood cell count (WBC ) , platelet count (PLT ) , alanine aminotransferase (ALT ) , aspartate aminotransferase (AST) ,creatine kinase (CK) ,lactate dehydrogenase (LDH) ,prothrombin time (PT) ,activated partial thromboplastin time (APTT) and thrombin time (TT) .Continuous variables with normal distribution were compared with t test ,and those with non‐normal distribution were compared with nonparametric test ;categorical variables were compared with χ2 test .Univariate Logistic regression was used to evaluate the risk factors associated with death .Results For the deceased patients and the survivors ,the APTT were 56 .40 s and 44 .45 s ,respectively (Z=5 .419 ,P=0 .04) at day 1—7 .Those were 66 .25 s and 36 .85 s ,respectively (Z=10 .112 ,P=0 .009) at day 8—10 ,and (125 .06 ± 11 .88) s and (33 .44 ± 6 .50) s ,respectively (t=45 .760 ,P 15 s (OR= 24 .00 ,95% CI:1 .99—289 .60) ,APTT>70 s (OR= 42 .67 ,95% CI:3 .54—514 .85) and TT > 120 s (OR= 0 .14 ,95% CI:0 .02—0 .88) were risk factors for the death of SFTS patients (all P< 0 .05) .Conclusion Prolonged APT T ,T T and PT at early stage and progressively increasing during the disease course suggest poor prognosis of SFTS .

A review on the epidemiologic features of severe fever with thrombocytopenia syndrome / 中华流行病学杂志

Severe fever with Thrombocytopenia Syndrome (SFTS) is an emerging hemorrhagic fever disease in the rural areas of east-central China,which is caused by SFTSV-a newly discovered bunyavirus.SFTSV is most likely transmitted by tick bites but can also be transmitted within human beings.The onset of SFTS is sudden and with rapid progress,with main clinical manifestations as fever,thrombocytopenia,leucopenia and gastrointestinal and hepatorenal dysfunctions.Some patients may die from multiple organ failure,and the case fatality rate is approximately 10％.In this paper,we use the method of literature review to summarize the recent research progress of SFTS which includes the epidemic distribution characteristics,medium of transmission,host animals,transmission routes and susceptibility in the general population.

A review on the epidemiologic features of severe fever with thrombocytopenia syndrome / 中华流行病学杂志

Severe fever with Thrombocytopenia Syndrome (SFTS) is an emerging hemorrhagic fever disease in the rural areas of east-central China,which is caused by SFTSV-a newly discovered bunyavirus.SFTSV is most likely transmitted by tick bites but can also be transmitted within human beings.The onset of SFTS is sudden and with rapid progress,with main clinical manifestations as fever,thrombocytopenia,leucopenia and gastrointestinal and hepatorenal dysfunctions.Some patients may die from multiple organ failure,and the case fatality rate is approximately 10％.In this paper,we use the method of literature review to summarize the recent research progress of SFTS which includes the epidemic distribution characteristics,medium of transmission,host animals,transmission routes and susceptibility in the general population.

Epidemiological characteristics of severe fever with thrombocytopenia syndrome in Zhoushan, Zhejiang, 2011-2013 / 中华流行病学杂志

Objective To analyze the epidemiological characteristics of severe fever cases,with thrombocytopenia syndrome (SFTS) in Zhoushan,Zhejiang,2011-2013 and to provide evidence for the development of related strategies for prevention and control of the disease.Methods Data was collected from the studies and related demography of the cases with SFTS in Zhoushan,2011-2013.Clinical and epidemiological characteristics of the cases with SFTS were analyzed descriptively.Results During 2011-2013,45 SFTS cases were reported in Zhoushan city,with fatality rate as 11.11％ (5/45),including 41 cases (91.11％) reported in Daishan county.Most cases aged 50 or over,residing in hilly regions (93.33％).The epidemic peak was seen from May to July (84.44％).Incidence rates of the disease did not show significant statistical differences between males and females.Most cases were farmers (42.22％) and housewives (31.11％).Most patients complained of fever (97.78％),anorexia (91.11％),fatigue (62.22％),chill (44.44％) and other non-specific clinical manifestations but all appeared progressive thrombocytopenia and leucopenia.Sanitation condition of the patients was generally poor.68.89％ (31/45) of cases had farmed,mowed or involved in other outdoor activities in the previous two weeks,with some of them reported having exposed to tick bites.Three events were reported,epidemiologically.Conclusion SFTS in Zhoushan was a infectious disease with natural foci and caused by SFTSV.Ticks might serve as the main vectors for SFTSV,and might cause direct transmission between humans.Improving the environment for living and carrying out essential protective measures in outdoor activities seemed to be significant in decreasing the incidence rate of the disease.

Analysis of lymphocyte subsets and interleukin-2 receptor in patients with severe fever with thrombo-cytopenia syndrome in Zhoushan island / 中华微生物学和免疫学杂志

Objective To analyze the characteristics of lymphocyte subsets and interleukin-2 re-ceptor (CD25) in patients with severe fever with thrombocytopenia syndrome (SFTS) in Zhoushan island. Methods Automated blood analyzer , automatic biochemical analyzer and flow cytometry were used to meas-ure hematological parameters , biochemical parameters and lymphocyte subsets in patients with SFTS before and after treatment .The dynamic changes and correlation analysis were statistically analyzed .Results The counts of white blood cells (WBCs), platelets, total T cells and CD4+T cells in patients with SFTS before treatment were significantly lower than those in healthy subjects .The counts of WBCs and platelets were sig-nificantly increased after ten days of treatment , and the level of CD25+cells was higher than that in control group, but the level of total T cells and CD 4+T cells were still lower than those in healthy subjects ( P<0.05).Patients died of SFTS had significantly lower counts of total T cells , CD4+T cells, CD8+T cells and CD25+cells than cured patients (P<0.05).The level of CD25+cells and B cells were positively correlated with WBC level (P<0.05).Platelet level was positively correlated with the percentage of CD 4+T cells (P<0.05).The level of alanine aminotransferase and creatine kinase were positively correlated with the number of CD3+T and CD8+T cells (P<0.05).Conclusion SFTS virus infection affected the percentage of body′s immune cells, especially the level of CD4+T cells.The imbalanced immune system was correlated with the counts of WBCs , platelets and various enzymes in serum and it might be one of the factors causing extensive damage of multiple organs and tissues .

Prevalence and homology analysis on human and animals severe fever with thrombocytopenia syndrome virus infection in Yantai of Shandong province / 中华流行病学杂志

Objective To learn the prevalence of infection of human and animals severe fever with thrombocytopenia syndrome bunyavirus(SFTSV)in Yantai,Shandong province,and to analyze the pathogenic features of SFTSV as well as its relationship between human and animal hosts. Methods From April to November in 2011,3 576 serum samples were collected from domesticated animals,including sheep,cattle,pigs,dogs,chickens,in Laizhou and Penglai areas where fever with thrombocytopenia syndrome frequently occured among local residents. Total SFTSV antibodies and virus-specific nucleic acids of the serum were tested by ELISA and Real time RT-PCR,respectively. SFTSV infection on each animal was observed in different months. 2 590 human serum samples were also collected in Laizhou and Penglai areas,with IgG antibodies tested by ELISA. Virus was isolated with Vero cells from the serum which SFTSV viral nucleic acids were positive. S fragments were amplified by RT-PCR and sequenced,with homology analysis conducted on these sequences. Results The overall positive rate of serum samples from animals on the total SFTSV antibodies was 40.24%(1 439/3 576)while the positive rate for specific nucleic acids was 4.56%(163/3 576). The positive rates for SFTSV antibodies were 62.78%,52.97%,45.56%,28.73%,1.45%and the positive rates for specific nucleic acids were 5.72%,4.63%,3.02%,5.25%and 3.73%,in sheep,cattle,chickens,dogs, pigs,respectively. The antigens/antibodies for SFTSV in animals changed seasonally. The overall positive rate for SFTSV IgG antibody from 2 590 human samples was 5.41%. Thirteen virus strains were isolated from these serum samples(10 strains from human and 3 strains from animals). The nucleotide homology of 13S fragments’sequences ranged from 95.23%to 100.00%and the nucleotide homology with the isolates from other provinces were between 94.72%and 99.13%. The homology was considered to be high. Conclusion High prevalence of SFTSV infections occured both in human and domestic animals in Yantai city. The nucleotide sequences of SFTSV were highly homologous among human and domestic animals. The findings suggested that domesticated animals might serve as SFTSV proliferation and the hosts for transmission thus should be attached great importance.

Prevalence and homology analysis on human and animals severe fever with thrombocytopenia syndrome virus infection in Yantai of Shandong province / 中华流行病学杂志

Objective To learn the prevalence of infection of human and animals severe fever with thrombocytopenia syndrome bunyavirus(SFTSV)in Yantai,Shandong province,and to analyze the pathogenic features of SFTSV as well as its relationship between human and animal hosts. Methods From April to November in 2011,3 576 serum samples were collected from domesticated animals,including sheep,cattle,pigs,dogs,chickens,in Laizhou and Penglai areas where fever with thrombocytopenia syndrome frequently occured among local residents. Total SFTSV antibodies and virus-specific nucleic acids of the serum were tested by ELISA and Real time RT-PCR,respectively. SFTSV infection on each animal was observed in different months. 2 590 human serum samples were also collected in Laizhou and Penglai areas,with IgG antibodies tested by ELISA. Virus was isolated with Vero cells from the serum which SFTSV viral nucleic acids were positive. S fragments were amplified by RT-PCR and sequenced,with homology analysis conducted on these sequences. Results The overall positive rate of serum samples from animals on the total SFTSV antibodies was 40.24%(1 439/3 576)while the positive rate for specific nucleic acids was 4.56%(163/3 576). The positive rates for SFTSV antibodies were 62.78%,52.97%,45.56%,28.73%,1.45%and the positive rates for specific nucleic acids were 5.72%,4.63%,3.02%,5.25%and 3.73%,in sheep,cattle,chickens,dogs, pigs,respectively. The antigens/antibodies for SFTSV in animals changed seasonally. The overall positive rate for SFTSV IgG antibody from 2 590 human samples was 5.41%. Thirteen virus strains were isolated from these serum samples(10 strains from human and 3 strains from animals). The nucleotide homology of 13S fragments’sequences ranged from 95.23%to 100.00%and the nucleotide homology with the isolates from other provinces were between 94.72%and 99.13%. The homology was considered to be high. Conclusion High prevalence of SFTSV infections occured both in human and domestic animals in Yantai city. The nucleotide sequences of SFTSV were highly homologous among human and domestic animals. The findings suggested that domesticated animals might serve as SFTSV proliferation and the hosts for transmission thus should be attached great importance.