Süss Jochen, Klaus Christine, Diller Roland, Schrader Christina, Wohanka Nikolaus, Abel Ulrich
National Reference Laboratory for Tick-Borne Diseases, Friedrich-Loeffler-Institute, Federal Research Institute for Animal Health, Naumburger Strasse 96a, D-07743 Jena, Germany.
Int J Med Microbiol. 2006 May;296 Suppl 40:63-8. doi: 10.1016/j.ijmm.2005.12.005. Epub 2006 Feb 21.
Traditionally, the classification of risk areas of tick-borne encephalitis (TBE) is based on the recording of autochthonous cases of the disease. In Germany, an extension of these areas over the years and an increasing virus prevalence in ticks have been observed in recent years. Registration of foci with autochthonous TBE cases, recording of disease incidence and virus prevalence in ticks are all proven epidemiological methods to characterize TBE risk areas. These data are necessary for a scientifically proven recommendation of TBE vaccines, and they need to be updated regularly. These epidemiological methods have advantages and disadvantages with respect to the risk assessment of TBE areas. Despite the fact that these methods are suitable for risk assessment in practice, disease incidence (new cases per year/100,000 inhabitants) and virus prevalence in questing ticks did not correlate. Using nested RT-PCR we were able to demonstrate that the prevalence of TBE virus (TBEV) in ticks removed from humans was significantly higher than in unfed, free-living Ixodes ricinus of the same area. The 561 ticks collected from humans in doctors' surgeries in Bavaria in 2002 were examined by nRT-PCR. The estimated overall virus prevalence in tested ticks was 8.8% (95% CI: 6.45-11.57%). The removed ticks examined were classified according to the sites of exposure of the patients in the individual districts. Peak values were measured in the district of Regen with 20.6% and in the district of Freyung-Grafenau with 18.3%. In recent studies on unfed I. ricinus (nymphs, adults), the average TBEV prevalence in ticks in Bavarian risk areas was between 0.5% and 2%.
传统上，蜱传脑炎（TBE）风险区域的划分是基于对该疾病本土病例的记录。在德国，近年来已观察到这些区域逐年扩大，蜱中病毒流行率也不断上升。记录有本土TBE病例的疫源地、记录蜱中的疾病发病率和病毒流行率，都是用于描述TBE风险区域的经过验证的流行病学方法。这些数据对于科学地推荐TBE疫苗是必要的，并且需要定期更新。这些流行病学方法在TBE区域的风险评估方面有优点也有缺点。尽管这些方法在实践中适用于风险评估，但疾病发病率（每年新发病例数/10万居民）与搜索蜱中的病毒流行率并无关联。通过巢式逆转录聚合酶链反应（nested RT-PCR），我们能够证明从人体采集的蜱中TBE病毒（TBEV）的流行率显著高于同一区域未进食的自由生活蓖麻硬蜱（Ixodes ricinus）。2002年在巴伐利亚州医生诊所从人体采集的561只蜱，通过nRT-PCR进行了检测。检测的蜱中估计的总体病毒流行率为8.8%（95%置信区间：6.45 - 11.57%）。根据患者在各个地区的暴露部位对采集的蜱进行分类。在雷根区测得峰值为20.6%，在弗赖翁 - 格拉费瑙区为18.3%。在最近对未进食的蓖麻硬蜱（若虫、成虫）的研究中，巴伐利亚风险区域蜱中TBEV的平均流行率在0.5%至2%之间。
