Fifth Branch, Centers for Disease Control, Department of Health, No. 180 Tz-You 2nd Rd., Tzo-Ying Dist., Kaohsiung City, Taiwan, ROC.
J Infect. 2011 Jan;62(1):39-44. doi: 10.1016/j.jinf.2010.10.008. Epub 2010 Oct 27.
The aim of this study was to assess the clinical significance of serological profiles suggestive of chronic Q fever after acute infection.
A prospective follow-up study consisting of two separate cohorts was conducted to monitor the serological evolution of Q fever. The first cohort comprised subjects with acute Q fever diagnosed in 2004-2007 and the second enrolled subjects whose infection occurred in 2009. The indirect immunofluorescence assay was used for serological monitoring, with serum PCR testing added for subjects whose serological profiles revealed high titers of anti-phase I IgG≥800, titers suggestive of chronic Q fever.
In the first cohort of 92 persons, seventeen (18%) subjects had serological profiles suggestive of chronic Q fever (titers of anti-phase I IgG: 1280-5120, median: 1280) after a median follow-up period of 606.5 days. After a further follow-up (median period: 592 days) exclusively for those seventeen subjects, serological resolution with fourfold decrease of titers of anti-phase I IgG was noted in five of them. In the second cohort, only one (4%) of the twenty-eight subjects had high levels of anti-phase I IgG 180 days after acute infection. All the eighteen subjects with high levels of anti-phase I IgG were asymptomatic and had negative serum PCR testing. The different prevalence of subjects with high titers of anti-phase I IgG in the two cohorts was associated with duration of follow-up period (P < .01).
Subjects with high titers of anti-phase I IgG≥800 was not uncommon and might not be detected until more than six months after acute Q fever infection. Asymptomatic subjects with high levels of anti-phase I IgG alone should not be treated as chronic Q fever and might not need continued serological monitoring in the absence of predisposing factors to chronic Q fever.
本研究旨在评估急性感染后提示慢性 Q 热的血清学特征的临床意义。
进行了一项前瞻性随访研究，包括两个独立的队列，以监测 Q 热的血清学演变。第一队列包括 2004-2007 年诊断为急性 Q 热的患者，第二队列包括 2009 年感染的患者。采用间接免疫荧光法进行血清学监测，对于血清学特征显示高滴度抗相 I IgG≥800（提示慢性 Q 热的滴度）的患者，增加血清 PCR 检测。
在第一队列的 92 名患者中，17 名（18%）患者在中位随访 606.5 天后出现血清学特征提示慢性 Q 热（抗相 I IgG 滴度：1280-5120，中位数：1280）。在对这 17 名患者进行进一步随访（中位随访期：592 天）后，5 名患者的抗相 I IgG 滴度出现了四倍下降，血清学特征得到了缓解。在第二队列中，仅 1 名（4%）的 28 名患者在急性感染后 180 天出现高滴度抗相 I IgG。所有 18 名抗相 I IgG 水平高的患者均无症状且血清 PCR 检测结果为阴性。两个队列中高滴度抗相 I IgG 患者的不同患病率与随访时间有关（P<.01）。
高滴度抗相 I IgG≥800 的患者并不少见，可能要在急性 Q 热感染后超过 6 个月才能发现。仅有高滴度抗相 I IgG 且无症状的患者不应被视为慢性 Q 热，并且在没有慢性 Q 热的诱发因素的情况下，可能不需要继续进行血清学监测。
