2010年湖北省发热伴血小板减少综合征的流行病学分析

Epidemiologic analysis on severe fever with thrombocytopenia syndrome in Hubei province, 2010

目的探讨湖北省新发传染病——发热伴血小板减少综合征（SFTS）的流行特征和危险因素。方法2010年在湖北省随州、黄冈、武汉市乡镇卫生院和二级以上综合医院设置监测点，培训全省县级及以上医疗机构感染科医生，开展报告病例的流行病学个案调查，采集血样检测和分离病毒，在高发地区开展健康人群和家畜抗体水平调查及媒介蜱监测。结果2010年湖北省报告病例来自11个市（州）、32个县（区）和100个乡镇，共报告188例，其中死亡21例，报告发病率为0．33／10万，病死率为11．2％。流行病学调查显示，病例报告地区为丘陵地带（海拔28～940m）；报告发病时间为4—12月，高峰在5—9月；病例年龄11～81（M=56）岁；农民占95．3％；病例发病前两周内均无外出史，93．6％从事与农业生产相关工作，64．2％有皮肤破损，52．8％有明显蜱暴露史，22．0％有明确蜱叮咬史。采集病例血液标本129例（68．6％），87例（67．4％）Realtime-PCR检测发热伴血小板减少综合征病毒（SFTSV）阳性；用微量中和试验检测急性期和恢复期血标本，11份SFTSV中和抗体阳转或呈4倍增高；2例血标本分离到SFTSV。健康人群总抗体阳性率为3．8％，犬、羊和牛总抗体阳性率分别为55．0％（6／11）、36．7％（2／3）和80．0％（4／5）；草蜱、牛蜱、羊蜱PCR检测阳性。结论湖北省SFTS疫区内人和家畜感染SFTSV。蜱可能是传播媒介，人群劳作中皮肤破损、接触蜱或被蜱叮咬可能是该病的危险因素之一。

Objective To identify the epidemic characteristics and risk factors of an emerging infectious disease--severe fever with thrombocytopenia syndrome （SFTS） in Hubei province. Methods Active surveillance program on SFTS was set up in monitoring sites--hospitals, at the township level or above, in Suizhou, Huanggang and Wuhan from January to December, 2010. Specific surveillance program on SFTS was launched across the province in hospitals above the county level. Cases that matched the definition of surveillance case were identified and reported to Centers for Disease Control and Prevention （CDCs）. Cases were interviewed and their blood samples collected and detected using PCR and virus isolation. We also conducted serum antibody surveys among healthy population and livestock and surveillance on vector ticks in those high-epidemic areas. Results 188 cases that matched the definition of surveillance case and 21 deaths were reported in 11 cities, 32 countries and 100 towns in 2010, with an incidence rate of 0.33/106. The fatality rate was 11.2%. Data showed that the patients were from hilly areas at the altitude elevated between 28-940 meters. The epidemic period was between April and December with the peak from May to September. The youngest case was an ll-year old, while the eldest was 81 with median age as 56-year old. 95.3% of the patients were farmers. All Patients did not have the history of traveling, two weeks before the onset of SFTS. 93.6% of the patients engaged in different kind of work which was associated with agriculture. 52.8% of the patients had been exposed to ticks. 22.0% of the patients had been bitten by ticks. Skin injury was found in 64.2% of the patients. Samples from 129 cases （68.6%） were collected and detected, with 67.4% of them （87 cases） showed positive by Real time-PCR for SFTS virus. An elevation in antibody titer by a factor of four or evidence of sero-conversion was observed in 11 patients; SFTS virus was isolated from 2 patients. The total antibody positive rates were 3.8%, 55.0% （6/11 ）, 36.7% （2/3） and 80.0% （4/5） respectively in healthy population, dogs, sheep and cows. Ticks from grass, cattle and sheep were detected positive by Real time-PCR. Condusion Most cases of SFTS in Hubei were infected by SFTS virus, and cases of livestock were infected by SFTS virus. Ticks might serve as an important vector. Skin injury, exposure to tick bites seemed to be the risk factors.