Koetsveld Joris, Tijsse-Klasen Ellen, Herremans Tineke, Hovius Joppe W R, Sprong Hein
Centre for Experimental and Molecular Medicine, Academic Medical Center, Meibergdreef 9, 1105AZ Amsterdam, The Netherlands.
Centre for Infectious Disease Control, Institute for Public Health and Environment, Antonie van Leeuwenhoeklaan 9, 3721 MA Bilthoven, The Netherlands.
Ticks Tick Borne Dis. 2016 Mar;7(2):371-7. doi: 10.1016/j.ttbdis.2015.12.010. Epub 2015 Dec 17.
Only a few reported cases indicate that Rickettsia helvetica and Rickettsia monacensis can cause disease in humans. Exposure to these two spotted fever group (SFG) rickettsiae occurs through bites of Ixodes ricinus, also the primary vector of Lyme borreliosis in Europe. To date, it is unclear how often exposure to these two microorganisms results in infection or disease. We show that of all the Borrelia burgdorferi s.l.-positive ticks, 25% were co-infected with rickettsiae. Predominantly R. helvetica was detected while R. monacensis was only found in approximately 2% of the ticks. In addition, exposure to tick-borne pathogens was compared by serology in healthy blood donors, erythema migrans (EM)-patients, and patients suspected of Lyme neuroborreliosis (LNB). As could be expected, seroreactivity against B. burgdorferi sensu lato was lower in blood donors (6%) compared to EM patients (34%) and suspected LNB cases (64%). Interestingly, seroreactivity against SFG Rickettsia antigens was not detected in serum samples from blood donors (0%), but 6% of the EM patients and 21% of the LNB suspects showed anti-rickettsial antibodies. Finally, the presence of B. burgdorferi s.l. and Rickettsia spp. in cerebrospinal fluid samples of a large cohort of patients suspected of LNB (n=208) was investigated by PCR. DNA of B. burgdorferi s.l., R. helvetica and R. monacensis was detected in seventeen, four and one patient, respectively. In conclusion, our data show that B. burgdorferi s.l. and SFG rickettsiae co-infection occurs in Dutch I. ricinus and that Lyme borreliosis patients, or patients suspected of Lyme borreliosis, are indeed exposed to both tick-borne pathogens. Whether SFG rickettsiae actually cause disease, and whether co-infections alter the clinical course of Lyme borreliosis, is not clear from our data, and warrants further investigation.
仅有少数报告病例表明，瑞士立克次体和蒙氏立克次体可导致人类发病。接触这两种斑点热群（SFG）立克次体是通过蓖麻硬蜱叮咬发生的，蓖麻硬蜱也是欧洲莱姆病螺旋体病的主要传播媒介。迄今为止，尚不清楚接触这两种微生物后感染或发病的频率有多高。我们发现，在所有携带伯氏疏螺旋体狭义种呈阳性的蜱中，25%同时感染了立克次体。检测到的主要是瑞士立克次体，而蒙氏立克次体仅在约2%的蜱中被发现。此外，通过血清学方法比较了健康献血者、游走性红斑（EM）患者以及疑似莱姆神经疏螺旋体病（LNB）患者接触蜱传病原体的情况。不出所料，与EM患者（34%）和疑似LNB病例（64%）相比，献血者（6%）对狭义伯氏疏螺旋体的血清反应性较低。有趣的是，在献血者的血清样本中未检测到针对SFG立克次体抗原的血清反应性（0%），但6%的EM患者和21%的疑似LNB患者显示出抗立克次体抗体。最后，通过聚合酶链反应（PCR）研究了一大群疑似LNB患者（n = 208）的脑脊液样本中狭义伯氏疏螺旋体和立克次体属的存在情况。分别在17例、4例和1例患者中检测到了狭义伯氏疏螺旋体、瑞士立克次体和蒙氏立克次体的DNA。总之，我们的数据表明，狭义伯氏疏螺旋体和SFG立克次体在荷兰的蓖麻硬蜱中存在共同感染，并且莱姆病螺旋体病患者或疑似莱姆病螺旋体病患者确实接触了这两种蜱传病原体。我们的数据尚不清楚SFG立克次体是否真的会导致疾病，以及共同感染是否会改变莱姆病螺旋体病的临床病程，这值得进一步研究。
