Department of Bacteria, Parasites and Fungi, Statens Serum Institut, Artillerivej 5, Copenhagen, Denmark.
Department of Clinical Microbiology, Slagelse Hospital, Slagelse, Denmark.
BMC Infect Dis. 2018 Jul 11;18(1):325. doi: 10.1186/s12879-018-3210-x.
With a prevalence of 4.7-13% in Danish Ixodes ricinus ticks, Rickettsia helvetica is one of the most frequently detected tick-borne organisms in Denmark. Most reports of human exposure have described asymptomatic seroconversion or a mild, self-limiting flu-like illness but it has also been implicated as a cause of subacute lymphocytic meningitis. Because Borrelia burgdorferi sensu lato (Bbsl) and R. helvetica are both found in the same tick species, potential co-transmission is a possibility. We examined 1) the seroprevalence of anti-rickettsia antibodies in patients investigated for Lyme neuroborreliosis (LNB), and 2) the cerebrospinal fluid (CSF) and sera of same patients for the presence of Rickettsia DNA.
Ninety-nine sera and 87 CSF samples from patients with intrathecal synthesis of anti-Borrelia antibodies and 101 sera and 103 CSF samples from patients with no detectable intrathecal synthesis were retrospectively examined for this study. Sera were analyzed for antibodies against spotted fever group (SFG) rickettsiae and both the CSF and sera were tested for Rickettsia DNA using a genus-specific real-time PCR.
Of the patients tested for LNB, 32% (64/200) had IgG antibodies against SFG rickettsiae. Among patients with confirmed intrathecal synthesis of Borrelia-specific antibodies, 38% (38/99) exhibited IgG antibodies. None of these values were statistically significant when compared with sera from healthy blood donors (p = 0.7 and 0.19). Rickettsia DNA was found in the CSF of 4% (8/190) of patients.
No statistically significant difference was found in the seroprevalence of anti-rickettsia antibodies in patients tested for LNB and healthy blood donors, indicative of a low rate of exposure in this group of patients. Eight patients showed evidence of Rickettsia DNA in the CSF, five of whom had LNB. However, cycle threshold (Ct) values were high, indicating low concentrations of DNA, and no apparent alteration in the clinical manifestations of LNB were noted in the medical records of these patients.
在丹麦的硬蜱中，赫尔维西亚立克次体的流行率为 4.7-13%，是丹麦最常检测到的蜱传病原体之一。大多数人类接触的报告都描述了无症状的血清转化或轻度、自限性流感样疾病，但它也被认为是亚急性淋巴细胞性脑膜炎的原因。由于伯氏疏螺旋体亚种（Bbsl）和赫尔维西亚立克次体都存在于同一种蜱中，因此存在潜在的共同传播的可能性。我们检查了 1）接受莱姆神经Borreliosis（LNB）检查的患者中抗立克次体抗体的血清患病率，以及 2）同一患者的脑脊液（CSF）和血清中是否存在立克次体 DNA。
对 99 份有鞘内合成抗Borrelia 抗体的患者的血清和 87 份脑脊液样本以及 101 份无鞘内合成的患者的血清和 103 份脑脊液样本进行了回顾性检查。血清用于检测斑点热群（SFG）立克次体抗体，CSF 和血清均使用种特异性实时 PCR 检测立克次体 DNA。
在接受 LNB 检查的患者中，有 32%（64/200）的 IgG 抗体对 SFG 立克次体呈阳性。在有确诊的鞘内合成 Borrelia 特异性抗体的患者中，有 38%（38/99）的 IgG 抗体呈阳性。与健康献血者的血清相比，这些值均无统计学意义（p=0.7 和 0.19）。在 190 名患者的 CSF 中发现了 4%（8/190）的立克次体 DNA。
在接受 LNB 检查的患者和健康献血者的抗立克次体抗体血清患病率中未发现统计学差异，表明该组患者的暴露率较低。有 8 名患者的 CSF 中存在立克次体 DNA，其中 5 名患有 LNB。然而，循环阈值（Ct）值较高，表明 DNA浓度较低，并且在这些患者的病历中未观察到 LNB 的临床表现有明显改变。
