Huang Xiaoxia, Wang Shiwen, Wang Xianjun, Lyu Yong, Jiang Mei, Chen Deying, Li Kaichun, Liu Jingyu, Xie Shaoyu, Lyu Tao, Sun Jie, Xu Pengpeng, Cao Minghua, Liang Mifang, Li Dexin
National Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, 155 Changbai Road, Changping District, Beijing, 102206, People's Republic of China.
Shandong Center for Disease Control and Prevention, Jinan, Shandong Province, People's Republic of China.
BMC Infect Dis. 2018 Feb 5;18(1):66. doi: 10.1186/s12879-018-2970-7.
Severe fever with thrombocytopenia syndrome (SFTS) is a severe viral disease caused by SFTSV. It is important to estimate the rate of missed SFTS diagnosis and to further understand the actual incidence in high endemic areas in China.
This study was conducted in two high SFTS endemic provinces in 2015. Patients hospitalized in 2014 or within 1 year before investigation were selected after considering their clinical manifestations, specifically, fever, platelet, and white blood cell. During retrospective investigation, sera were collected to detect SFTSV antibodies to assess SFTSV infection. To further understand SFTSV infection, acute phase sera were detected; SFTSV infection rate among a healthy population was also investigated to determine the basic infection level.
In total, 246 hospitalized cases were included, including 83 cases (33.7%) with fever, thrombocytopenia and leukopenia, 38 cases (15.4%) with fever and thrombocytopenia but without leukopenia, and 125 cases (50.8%) without fever but with thrombocytopenia and leukopenia. In total, 13 patients (5.3%) were SFTSV IgM antibody-positive, 48 (19.5%) were IgG-positive. Of the 13 IgM-positive cases, 11 (84.6%) were IgG-positive (9 with titres ≥1:400). Seropositive rates of antibodies were high (8.4% for IgM and 30.1% for IgG) in patients with fever, thrombocytopenia and leukopenia. Furthermore, among IgG-positive cases in this group, 76% (19/25) of patients' IgG antibody titres were ≥1:400. Additionally, 28 of 246 cases were initially diagnosed with suspected SFTS and were then excluded, and 218 patients were never diagnosed with SFTS; the seropositive rates of IgM and IgG in these two groups were 25% and 67.9% and 2.8% and 13.3%, respectively. These rates were 64.3% and 21.4% in 14 sera collected during acute phase of the 28 cases mentioned above. Seropositive rate of SFTSV IgG was only 1.3% in the patient-matched healthy group, and no IgM antibody was detected. A preliminary estimate of 8.3% of SFTS cases were missed in SFTS high endemic provinces.
The actual SFTS incidence was underestimated. Effective measures such as adding a new SFTS case category - "SFTS clinical diagnosis cases" or using serological detection methods during acute phase should be considered to avoid missed diagnoses.
发热伴血小板减少综合征（SFTS）是由SFTS病毒引起的一种严重病毒性疾病。在中国高流行地区，评估SFTS漏诊率并进一步了解实际发病率很重要。
本研究于2015年在两个SFTS高流行省份开展。选取2014年或调查前1年内住院的患者，考虑其临床表现，特别是发热、血小板和白细胞情况。在回顾性调查期间，采集血清检测SFTS病毒抗体以评估SFTS病毒感染。为进一步了解SFTS病毒感染情况，检测急性期血清；还调查了健康人群中的SFTS病毒感染率以确定基本感染水平。
共纳入246例住院病例，其中83例（33.7%）有发热、血小板减少和白细胞减少，38例（15.4%）有发热和血小板减少但无白细胞减少，125例（50.8%）无发热但有血小板减少和白细胞减少。共有13例患者（5.3%）SFTS病毒IgM抗体阳性，48例（19.5%）IgG阳性。在13例IgM阳性病例中，11例（84.6%）IgG阳性（9例滴度≥1:400）。发热、血小板减少和白细胞减少患者的抗体血清阳性率较高（IgM为8.4%，IgG为30.1%）。此外，该组IgG阳性病例中，76%（19/25）患者的IgG抗体滴度≥1:400。另外，246例病例中有28例最初被诊断为疑似SFTS，随后被排除，218例患者从未被诊断为SFTS；这两组的IgM和IgG血清阳性率分别为25%和67.9%以及2.8%和13.3%。上述28例病例急性期采集的14份血清中，这两个比例分别为64.3%和21.4%。患者匹配的健康组中SFTS病毒IgG血清阳性率仅为1.3%，未检测到IgM抗体。初步估计SFTS高流行省份中8.3%的SFTS病例被漏诊。
SFTS实际发病率被低估。应考虑采取有效措施，如增加新的SFTS病例分类——“SFTS临床诊断病例”或在急性期使用血清学检测方法以避免漏诊。
