Alekseev A N, Dubinina H V, Antykova L P, Dzhivanyan T I, Rijpkema S G, Kruif N V, Cinco M
Zoological Institute, Russian Academy of Sciences, St. Petersburg, Russia.
J Med Entomol. 1998 Mar;35(2):136-42. doi: 10.1093/jmedent/35.2.136.
Two isolated Baltic seashore populations of Ixodes ticks were studied as vectors of different Borrelia genospecies in Russia by using darkfield microscopy and modified polymerase chain reaction (PCR). In the Kalinigrad region (Kurish Spit, forests near the settlements of Lesnoye and Rybachy), 788 Ixodes ricinus (L.) adults and nymphs were collected by flagging and studied by darkfield microscopy during 1995-1996. There were 88 darkfield microscopy positive specimens (11.2%) of which 69 were also analyzed by PCR. Borrelia afzelii and B. garinii were found individually and together in ticks. In this region, on the Kurish Spit, 7 patients with tick borrelioses were observed: 2 in the Russian part of Spit and 5 in the Lithuanian part. A significant difference was found between Borrelia prevalence during the spring and fall peaks of tick abundance. Specimens that were darkfield microscopy positive prevailed in the fall (25.15%) in comparison with the spring peak (7.3%). The number of specimens with identified genospecies prevailed in the spring: 22 out of 35 versus 4 out of 31 in the fall. Among 29 PCR positive I. ricinus, 21 contained B. afzelii, 3 had B. garinii, and 2 had dual infection. In 1995, only B. afzelii infected specimens were observed. In the vicinity of St. Petersburg (the seashore of the northern Gulf of Finland, in forests near Lisy Nos, Morskaja) during 1992-1996, 31 patients with a tick-borne borrelioses were registered. We collected 487 Ixodes persulcatus Schulze by flagging and studied them by darkfield microscopy in 1995-1996 of which 144 ticks (29.6%) were darkfield microscopy positive. Sixty darkfield-positive specimens were analyzed by PCR, and in 88.3% of cases genospecies were identified. B. afzelii and B. garinii were identified individually and together in ticks. In 1995, I. persulcatus with dual infection prevailed with 11 out of 21 (52.4% positive), whereas in 1996, most I. persulcatus ticks contained B. garinii (81.2%). Dual infection was observed in 4 of 32 (12.5%) ticks. Dual infections in I. persulcatus females increased within the seasonal peak of tick activity as was observed in 1995 and in 1996. Many patients not only had erythema migrans, but also exhibited early neurological symptoms that coincided with the number of tick vectors that had dual infections in June, indicating that these patients were bitten by female ticks that had dual infections. A significant difference existed between levels of infection in I. ricinus and I. persulcatus, with all 3 types of Borrelia infection observed 2 times more often in I. persulcatus than in I. ricinus and dual infection occurred in I. persulcatus 3.7 times more often. It appeared that I. persulcatus is a much more dangerous vector of tick-borne borrelioses than I. ricinus.
通过暗视野显微镜检查和改良聚合酶链反应（PCR），对俄罗斯两个孤立的波罗的海沿岸地区的硬蜱种群作为不同伯氏疏螺旋体基因型的传播媒介进行了研究。在加里宁格勒地区（库尔斯沙嘴、列斯诺耶和雷巴奇定居点附近的森林），1995 - 1996年期间通过拖旗法收集了788只蓖麻硬蜱（L.）成虫和若虫，并通过暗视野显微镜检查进行研究。有88个暗视野显微镜检查阳性标本（11.2%），其中69个也进行了PCR分析。在蜱中分别和共同发现了阿氏疏螺旋体和加氏疏螺旋体。在该地区库尔斯沙嘴上，观察到7例蜱传疏螺旋体病患者：2例在沙嘴的俄罗斯部分，5例在立陶宛部分。在蜱数量的春季和秋季高峰期之间，伯氏疏螺旋体的患病率存在显著差异。与春季高峰期（7.3%）相比，秋季暗视野显微镜检查阳性的标本占优势（25.15%）。鉴定出基因型的标本数量在春季占优势：春季35个中有22个，秋季31个中有4个。在29个PCR阳性的蓖麻硬蜱中，21个含有阿氏疏螺旋体，3个含有加氏疏螺旋体，2个有双重感染。1995年，仅观察到感染阿氏疏螺旋体的标本。在圣彼得堡附近（芬兰湾北部海岸，利西诺斯、莫尔斯卡亚附近的森林），1992 - 1996年期间登记了31例蜱传疏螺旋体病患者。1995 - 1996年通过拖旗法收集了487只全沟硬蜱舒尔茨，并通过暗视野显微镜检查进行研究，其中144只蜱（29.6%）暗视野显微镜检查呈阳性。对60个暗视野阳性标本进行了PCR分析，88.3%的病例鉴定出了基因型。在蜱中分别和共同鉴定出了阿氏疏螺旋体和加氏疏螺旋体。1995年，双重感染的全沟硬蜱占优势，21只中有11只（阳性率52.4%），而1996年，大多数全沟硬蜱含有加氏疏螺旋体（81.2%）。在32只蜱中有4只（12.5%）观察到双重感染。如1995年和1996年所观察到的，全沟硬蜱雌蜱中的双重感染在蜱活动的季节性高峰期有所增加。许多患者不仅有游走性红斑，还表现出早期神经症状，这与6月份有双重感染的蜱传播媒介数量一致，表明这些患者被有双重感染的雌蜱叮咬。蓖麻硬蜱和全沟硬蜱的感染水平存在显著差异，所有3种伯氏疏螺旋体感染在全沟硬蜱中出现的频率是蓖麻硬蜱的2倍，双重感染在全沟硬蜱中出现的频率是蓖麻硬蜱中的3.7倍。看来全沟硬蜱作为蜱传疏螺旋体病的传播媒介比蓖麻硬蜱危险得多。
