Victorian Infectious Disease Service, Melbourne Health, Parkville, Victoria, Australia.
J Travel Med. 2014 Jul-Aug;21(4):235-9. doi: 10.1111/jtm.12122. Epub 2014 Apr 22.
There can be considerable overlap in the clinical presentation and laboratory features of dengue, malaria, and enteric fever, three important causes of fever in returned travelers. Routine laboratory tests including full blood examination (FBE), liver function tests (LFTs), and C-reactive protein (CRP) are frequently ordered on febrile patients, and may help differentiate between these possible diagnoses.
Adult travelers returning to Australia who presented to the Royal Melbourne Hospital with confirmed diagnosis of dengue, malaria, or enteric fever between January 1, 2000 and March 1, 2013 were included in this retrospective study. Laboratory results for routine initial investigations performed within the first 2 days were extracted and analyzed.
There were 304 presentations including 58 with dengue fever, 187 with malaria, and 59 with enteric fever, comprising 56% of all returned travelers with a febrile systemic illness during the study period. Significant findings included 9-fold and 21-fold odds of a normal CRP in dengue compared with malaria and enteric fever, respectively. The odds of an abnormally low white cell count (WCC) were also significantly greater in dengue versus malaria or enteric fever. Approximately one third of dengue presentations and almost half of the malaria presentations had platelet counts <100 × 10(9) /L. A normal CRP with leukopenia and/or thrombocytopenia occurred in 21% to 30% of dengue presentations, but not in malaria or enteric fever presentations.
There is a wide differential diagnosis for imported fever, but the non-specific findings of a normal CRP with a low WCC and/or low platelet count may provide useful information in addition to clinical clues to suggest dengue over malaria or enteric fever. Further systematic prospective studies among travelers could help define the potential clinical utility of these results in assisting the clinician when deciding for or against commencement of empiric antimicrobial therapy while awaiting confirmatory tests.
登革热、疟疾和肠热病是导致旅行者发热的三个重要原因，它们的临床症状和实验室特征可能存在较大重叠。发热患者通常会接受全血细胞检查（FBE）、肝功能检查（LFTs）和 C 反应蛋白（CRP）等常规实验室检查，这些检查结果可能有助于区分这些可能的诊断。
本回顾性研究纳入了 2000 年 1 月 1 日至 2013 年 3 月 1 日期间，在澳大利亚皇家墨尔本医院就诊且确诊为登革热、疟疾或肠热病的成年旅行者。提取并分析了他们在发病后前 2 天内进行的初始常规检查的实验室结果。
共有 304 例就诊，其中 58 例为登革热，187 例为疟疾，59 例为肠热病，占研究期间所有发热旅行者的 56%。研究发现，与疟疾和肠热病相比，CRP 正常的登革热患者发生的几率分别为 9 倍和 21 倍；与疟疾或肠热病相比，登革热患者白细胞计数（WCC）异常降低的几率也显著更高。大约三分之一的登革热患者和近一半的疟疾患者血小板计数<100×10(9)/L。白细胞减少症和/或血小板减少症伴 CRP 正常的情况在 21%至 30%的登革热患者中出现，但在疟疾或肠热病患者中并未出现。
对于输入性发热，有广泛的鉴别诊断，但除了临床线索外，CRP 正常、WCC 和/或血小板计数降低的非特异性发现也可能提供有用信息，有助于提示医生在等待确诊试验时，针对是否开始经验性抗菌治疗做出决策，特别是在考虑登革热而非疟疾或肠热病时。进一步针对旅行者开展系统性前瞻性研究，有助于明确这些结果在协助临床医生决定是否开始经验性抗菌治疗时的潜在临床应用价值。
