Department of Tropical Medicine, Infectious Diseases and Nephrology, University of Rostock Medical School, Ernst-Heydemann-Straße 6, 18057 Rostock, Germany.
Health Department of the State of Mecklenburg-West Pomerania, 18055 Rostock, Germany.
Biomed Res Int. 2014;2014:308371. doi: 10.1155/2014/308371. Epub 2014 Jul 8.
The incidence of tick-borne encephalitis has risen in Europe since 1990 and the tick-borne encephalitis virus (TBEV) has been documented to be spreading into regions where it was not previously endemic. In Mecklenburg-West Pomerania, a federal state in Northern Germany, TBEV was not detectable in over 16,000 collected ticks between 1992 and 2004. Until 2004, the last human case of TBE in the region was reported in 1985. Following the occurrence of three autochthonous human cases of TBE after 2004, however, we collected ticks from the areas in which the infections were contracted. To increase the chance of detecting TBEV-RNA, some of the ticks were fed on mice. Using nested RT-PCR, we were able to confirm the presence of TBEV in ticks for the first time after 15 years. A phylogenetic analysis revealed a close relationship between the sequences we obtained and a TBEV sequence from Mecklenburg-East Pomerania published in 1992 and pointed to the reemergence of a natural focus of TBEV after years of low activity. Our results imply that natural foci of TBEV may either persist at low levels of activity for years or reemerge through the agency of migrating birds.
自 1990 年以来，欧洲的蜱传脑炎发病率上升，蜱传脑炎病毒 (TBEV) 已被证实正在传播到以前非地方性流行的地区。在德国北部的梅克伦堡-前波美拉尼亚州，1992 年至 2004 年间采集的超过 16000 只蜱虫中未检测到 TBEV。直到 2004 年，该地区最后一例 TBE 人感染病例报告于 1985 年。2004 年之后，当地发生了三例本土人类 TBE 病例，我们开始从感染发生地采集蜱虫。为了增加检测 TBEV-RNA 的机会，我们给部分蜱虫喂了老鼠。通过巢式 RT-PCR，我们首次在 15 年后在蜱虫中确认了 TBEV 的存在。系统进化分析显示，我们获得的序列与 1992 年在梅克伦堡-前波美拉尼亚州发表的 TBEV 序列密切相关，表明 TBEV 的自然疫源地在多年低活动后重新出现。我们的研究结果表明，TBEV 的自然疫源地可能会多年来保持低活动水平，或者通过迁徙鸟类的活动重新出现。
