A clear and present danger: tick-borne diseases in Europe

Ticks can transmit a variety of viruses, bacteria or parasites that can cause serious infections or conditions in humans and animals. While tick-borne diseases are becoming an increasing and serious problem in Europe, tick-borne diseases are also responsible for major depressions in livestock production and mortality in sub-Saharan Africa, Latin America and Asia. This review will focus on the most important circulating tick-transmitted pathogens in Europe (Borrelia spp., Anaplasma phagocytophilum, Babesia spp., tick-borne encephalitis virus, Rickettsia spp. and Crimean-Congo hemorrhagic fever virus).     

新疆伊犁地区无形体流行病学调查及病原16SrRNA序列分析

目的调查新疆地区人、家畜动物包括羊、牛、马及野生动物旱獭、大尾黄鼠及家养马鹿等无形体感染及病原16SrRNA序列特征。方法采集伊犁地区正常人、牛、马、羊及野生啮齿动物大尾黄鼠、旱獭血液。 微量间接免疫荧光检测方法（mIFA）检测血清无形体IgM、IgG抗体。巢氏PCR扩增无形体16SrRNA基因并分析序列特征。结果当地人群无形体IgG抗体阳性率为5.3%;羊、牛及马为6.9%、6.3%及9.1%。 PCR结果发现羊、牛及马无形体16SrRNA基因检出率为38.9%、37.5%及36.4%。16SrRNA（228bp）序列分析显示存在明显变异株,同源比较结果提示这些变异株在我国其他地区及周边国家媒介及动物宿主中均有广泛分布。结论新疆伊犁地区存在人及家畜无形体感染。 开展发热病人无形体实验室调查及进一步人群、媒介种类、宿主与无形体生态学关系研究十分必要。     

人粒细胞无形体致病机制研究进展

人粒细胞无形体(Anaplasma phagocytophilum)是新发蜱传病原体,主要引起人无形体病.人粒细胞无形体感染以中性粒细胞为主,其次为嗜酸性粒细胞,急性期90%的粒细胞受到感染.病原体在宿主细胞内聚集,被囊膜包裹成小体,称为包涵体[1].该病主要表现发热、头痛、精神萎靡、肌痛等感冒样症状,部分患者有关节痛、胃肠道(恶心、呕吐和腹泻)、呼吸道、肝脏、中枢神经等症状,很少出现皮疹.实验室检测结果显示血小板和白细胞减少、贫血、肝转氨酶升高[1].     

Wild rodents and novel human pathogen candidatus Neoehrlichia mikurensis, Southern Sweden

We examined small mammals as hosts for Anaplasmataceae in southern Sweden. Of 771 rodents, 68 (8.8%) were infected by Candidatus Neoehrlichia mikurensis, but no other Anaplasmataceae were found. Candidatus N. mikurensis has recently been found in human patients in Germany, Switzerland, and Sweden, which suggests that this could be an emerging pathogen in Europe.     

Babesiosis in immunocompetent patients, Europe

We report 2 cases of babesiosis in immunocompetent patients in France. A severe influenza-like disease developed in both patients 2 weeks after they had been bitten by ticks. Diagnosis was obtained from blood smears, and Babesia divergens was identified by PCR in 1 case. Babesiosis in Europe occurs in healthy patients, not only in splenectomized patients.     

浙江省啮齿动物、牛和羊感染的无形体种属

目的 鉴定浙江省啮齿动物和家畜中存在的无形体种属,分析其16S rRNA基因变异。方法 在浙江省部分山区,采集啮齿动物肝脾和家畜全血,巢式PCR扩增无形体属16S rRNA片段并测序,多序列比对和系统发生分析。结果 浙江省啮齿动物、牛和山羊中检测到的16S rRNA基因序列分布在6个无形体种群中,包括嗜吞噬细胞无形体、牛无形体、边缘无形体、血小板无形体,而新被认识的山羊无形体新种被证实一直存在于牛和羊中。啮齿动物除了存在嗜吞噬细胞无形体感染外,本文首次报道社鼠、黄毛鼠和青毛鼠中还存在牛无形体感染。另外,发现广泛存在于野鼠中与牛无形体相关但不同的一个无形体新种。结论 浙江省的啮齿动物和家畜中至少存在6个无形体种,推测存在潜在的变异和新种,还不清楚基因多样性是否会导致发病率、致病性或临床特征上的一些变化。     

Frontline: control of Anaplasma phagocytophilum, an obligate intracellular pathogen, in the absence of inducible nitric oxide synthase, phagocyte NADPH oxidase, tumor necrosis factor, Toll-like receptor (TLR)2 and TLR4, or the TLR adaptor molecule MyD88

Anaplasma phagocytophilum is an obligate intracellular bacterium that is related to rickettsial organisms and replicates in the hostile environment of neutrophils. Previous studies with SCID mice suggested that T and/or B cells are required for its control in vivo. Here, we used mice deficient for Toll-like receptor (TLR)2 and TLR4, MyD88, tumor necrosis factor, inducible nitric oxide synthase, or phagocyte NADPH oxidase (gp91(phox-/-)) to define the pathways that are critical for the recognition and the killing of this pathogen. Whereas SCID mice developed a 60-fold higher bacterial load in the blood compared to wild-type mice and succumbed to infection, all other gene-deficient mouse strains were fully capable in overcoming a systemic infection with A. phagocytophilum. From these data we conclude that effector mechanisms that are crucial to the defense against numerous other intracellular pathogens are dispensable for the control of A. phagocytophilum.     

The seroprevalence of Anaplasma phagocytophilum in global human populations: A systematic review and meta‐analysis

The tick‐borne pathogen Anaplasma phagocytophilum is an emerging infectious disease threat, but the overall A. phagocytophilum seroprevalence in humans is unclear. We performed a systematic search of English databases for literature published from 1994 to 2018. Studies reporting serological evidence of A. phagocytophilum infection in humans were included, and the information was extracted by two authors independently. As the study heterogeneity was significant, a random‐effects model was used to calculate the overall pooled seroprevalence. Data from 56 studies involving 28,927 individuals from four continents were included. The seroprevalence reported by the studies ranged from 0% to 37.26%. The overall pooled A. phagocytophilum seroprevalence in humans was 8.4% (95% CI: 6.6%–10.4%). The seroprevalence was highest in high‐risk population (13.8%) and lowest in healthy population (5.0%). The estimated A. phagocytophilum seroprevalence of febrile patient, tick‐bitten and tick‐borne diseases populations was 6.4%, 8.0% and 9.0%, respectively. This meta‐analysis demonstrated first A. phagocytophilum seroprevalence estimates in different populations (healthy, febrile patient, high‐risk, tick‐bitten and tick‐borne diseases populations); it seems likely that present surveillance efforts are missing mild or asymptomatic infections of humans.