旅行者登革热的临床特征及实验室诊断中的陷阱
Clinical features and pitfalls in the laboratory diagnosis of dengue in travellers.
作者信息
Wichmann Ole, Stark Klaus, Shu Pei-Yun, Niedrig Matthias, Frank Christina, Huang Jyh-Hsiung, Jelinek Tomas
机构信息
Berlin Institute of Tropical Medicine, Spandauer Damm 130, 14050 Berlin, Germany.
出版信息
BMC Infect Dis. 2006 Jul 21;6:120. doi: 10.1186/1471-2334-6-120.
BACKGROUND
Several enzyme-linked immunosorbent assay (ELISA)-kits are commercially available for the rapid diagnosis of dengue infection, and have demonstrated good sensitivity and specificity in paired serum samples. In practice, however, often only one blood sample is available from febrile travellers returning from dengue endemic areas.
METHODS
To evaluate the diagnostic value of positive dengue antibody-titres performed by a standard ELISA (PanBio IgM- and IgG-ELISA) in single serum samples (regarded as "probable infection"), 127 positive samples were further analyzed using envelope/membrane IgM-, and nonstructural protein 1 IgM- and IgG-ELISAs, immunofluorescence assays, and real-time reverse transcription polymerase chain reaction assays (RT-PCR). A combination of the test-results served as the diagnostic "gold standard". A total of 1,035 febrile travellers returning from dengue-endemic countries with negative dengue-serology and RT-PCR served as controls to compare clinical and haematological features.
RESULTS
Overall, only 64 (positive predictive value = 50%) of the probable cases were confirmed by additional analysis and 54 (42.5%) were confirmed to be "false-positive". Rash was the only clinical feature significantly associated with confirmed dengue fever. The combination of thrombocytopenia and leucopenia was present in 40.4% of confirmed and in 6.1% of false-positive cases. Thus, the positive predictive value for the combination of positive PanBio-ELISA plus the two haematological features was 90.5%.
CONCLUSION
The examination of paired serum samples is considered the most reliable serodiagnostic procedure for dengue. However, if only one blood sample is available, a single positive ELISA-result carries a high rate of false-positivity and should be confirmed using a second and more specific diagnostic technique. In the absence of further testing, platelet and white blood cell counts are helpful for the correct interpretation.
背景
有几种酶联免疫吸附测定（ELISA）试剂盒可用于登革热感染的快速诊断，并且在配对血清样本中已显示出良好的敏感性和特异性。然而，在实际操作中，从登革热流行地区返回的发热旅行者通常仅提供一份血样。
方法
为了评估标准ELISA（PanBio IgM和IgG ELISA）检测单一血清样本中登革热抗体阳性滴度的诊断价值（视为“可能感染”），使用包膜/膜IgM、非结构蛋白1 IgM和IgG ELISA、免疫荧光测定以及实时逆转录聚合酶链反应测定（RT-PCR）对127份阳性样本进行了进一步分析。将检测结果的组合用作诊断“金标准”。共有1035名从登革热流行国家返回且登革热血清学和RT-PCR检测结果为阴性的发热旅行者作为对照，以比较临床和血液学特征。
结果
总体而言，通过进一步分析仅确诊了64例可能病例（阳性预测值=50%），54例（42.5%）被确认为“假阳性”。皮疹是与确诊登革热显著相关的唯一临床特征。血小板减少和白细胞减少同时存在于40.4%的确诊病例和6.1%的假阳性病例中。因此，PanBio ELISA阳性加上这两种血液学特征的组合的阳性预测值为90.5%。
结论
配对血清样本检测被认为是登革热最可靠的血清学诊断方法。然而，如果只有一份血样，单一的ELISA阳性结果假阳性率很高，应使用第二种更特异的诊断技术进行确认。在没有进一步检测的情况下，血小板和白细胞计数有助于正确解读。
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