Red cell enzyme polymorphisms in Friuli Venezia Giulia (northeast Italy)

Seven erythrocyte enzyme polymorphisms (ACP1, ADA, ESD, GLO1, PGD, PGM1 and PGM2) were investigated in a sample of 673 unrelated adult individuals from Friuli Venezia Giulia (or Friuli) and Istria. The gene frequencies found in the four provincial samples of Friuli and Istria fall within the range previously reported for Italy, showing a genetic homogeneity among the considered samples. However, comparisons with data from ex-Yugoslavian samples--using the chi 2 test--showed rather marked differences, probably due to a real different genetic structure of the compared samples. A significant association was found assuming a linear relation between the ADA*2 allele frequencies and longitude (r = +0.5503) and between the PGD*C frequencies and latitude (r = -0.6483), suggesting the existence of a clinal trend for these allele frequencies in Italy. These results seem to disagree with foregoing conclusions stated by other authors, probably because these studies were carried out in an area either rather narrow from the geographical point of view or affected by small size migration movements.     

Ultrastructure of spirochetes isolated from Ixodes ricinus and Ixodes dammini

Two strains of Ixodes spirochetes, one isolated in the United States (B31) and the other in Sweden (G25), were examined by electron microscopy. Cells of strain G25 were 11-25 micron long with a wavelength of 2.1-2.4 micron and an amplitude of 0.4 micron. Eleven flagella were inserted subterminally at each end of the cell. Cells of strain B31 were similar but had eleven or seven flagella. Cytoplasmic tubules were not seen in cells of either strain. Although not identical, both strains showed ultrastructural details characteristic of the genus Borrelia.     

Tick-borne encephalitis virus in northern Italy: molecular analysis, relationships with density and seasonal dynamics of Ixodes ricinus

Ixodes ricinus ticks were collected from dragging vegetation and from shot roe deer in the province of Trento and Belluno in northern Italy. Ticks were pooled for analyses and from 1060 pools of ticks collected in the province of Belluno and 12390 tick samples collected in Trentino, four proved positive by immunofluorescence microscopy using a tick-borne encephalitis (TBE)-specific antiserum. The identity of the virus isolates was determined by RT-PCR cycle sequencing and they were all found to be closely similar (> 98% nucleotide identity) to typical western European TBE complex viruses as found in Austria. The isolates from Trentino differed from the Neudorfl strain of western European TBE virus at eight nucleotide positions but as these nucleotide substitutions were all synonymous, there were no amino acid changes. These results imply that the virus isolates in Trentino have changed slightly from the typical European strains isolated in nearby Austria. The abundance of questing ticks and ticks feeding on roe deer was greater in TBE positive hunting districts than in hunting districts where TBE complex viruses were only probable or believed to be absent. In TBE positive and probable districts synchrony in the seasonal dynamics of larvae and nymphs of L. ricinus was observed. This study provides evidence to suggest that roe deer may have an important role to play in the maintenance of tick density and in the persistence of TBE virus.     

Questing behaviour of Ixodes ricinus ticks (Acari: Ixodidae)

The vertical distribution in the vegetation of questing Ixodes ricinus ticks was investigated in two different vegetation types (high and low vegetation) at two localities in south-central Sweden during 1992-1993 (Toro) and 1995 (Bogesund). Significant correlations were found between the vertical distribution of immature ticks and the height of the vegetation. The greatest mean availabilities of the larvae and nymphs in low vegetation were in the intervals 0-9 and 30-39 cm, respectively. The larval numbers were greatest close to the ground (0-29 cm) in both high and low vegetation. The larval : nymphal ratio, at ground level at localities free of ground vegetation, varied between 8 : 1 and 32 : 1. In high vegetation, the greatest mean numbers of nymphal and adult ticks were at height intervals of 50-59 and 60-79 cm, respectively. These ranges are within the estimated height interval (40-100 cm) of the main part of the body surface of their preferred host, the roe deer (Capreolus capreolus). The presence of most questing I. ricinus larvae at ground level would favour the transmission of Borrelia burgdorferi s.l., since this is where the highly reservoir-competent rodents and shrews usually occur.     

Use of DNA sequences for Rickettsia identification in Ixodes ricinus ticks: the first detection of Rickettsia monacensis in Poland

The cosmopolitan tick Ixodes ricinus inhabiting Europe, including Poland, is a vector for many pathogens, such as various Rickettsia species, which spread to new territories. They are present mainly in the Mediterranean countries, but have also been found in Central Europe at increasing frequency. In the present study, the gltA gene, encoding citrate synthase, and an internal transcribed spacer (ITS) were employed to detect the DNA and identify the species of tick-borne pathogens of the Rickettsia genus. The presence of bacterial DNA was detected in 9.5% of the examined I. ricinus individuals. Based on the nucleotide sequences of the analysed genomic fragments, most pathogens were identified as Rickettsia helvetica, while Rickettsia monacensis was revealed in one case. We have described for the first time, to our knowledge, the occurrence of this species in Poland. Both markers employed in the experiments were successful in species identification of R. helvetica. The newly described species R. monacensis may be identified by the protein-coding gene, but the ITS nucleotide sequences proved insufficient.     

Autochthonous and migratory birds as a dispersion source for Ixodes ricinus in southern Italy

The present study was carried out in a protected wooded area, which is part of the Parco Regionale Gallipoli Cognato Piccole Dolomiti Lucane, one of the most important ecological reserves in southern Italy. From April 2010 to April 2011, 212 birds, comprising 22 species from 12 families, were captured and examined for ticks. A total of 75 (35.4?%) birds were found infested by ticks, with 451 ticks being collected. All ticks were identified as Ixodes ricinus, of which 241 (53.4?%) were larvae and 210 nymphs (46.6?%). The highest intensity of infestation was found in April 2010, when 117 ticks were retrieved on 25 birds. No ticks were found on birds (n?=?5) netted in December 2010. High infestation rates were recorded on blackbirds (Turdus merula) (90 %; 29 birds examined) and on mistle thrushes (Turdus viscivorus) (100?%; 2 birds examined). The highest intensity of infestation by larvae was found on wrens (5.6 larvae/bird) and by nymphs on mistle thrushes (11.5 nymphs/bird). Temperature and number of hours of light showed to influence the activity of larvae and nymphs. These data support the notion that birds may be responsible for the heterogeneous distribution of I. ricinus in Europe, thus playing a role in the epidemiology of certain tick-borne pathogens.     

Lacerta bilineata (Reptilia,Lacertidae) as a host of Ixodes ricinus (Acari,Ixodidae) in a protected area of northern Italy

A survey on the importance of Lacerta bilineata as host of Ixodes ricinus was conducted in Northern Italy over a three-year period. A total of 202 western green lizards were captured and a total of 2349 ticks were collected. All ticks were identified as I. ricinus; 53.2% and 46.7% were at the larval and nymphal stages, respectively. Tick number and prevalence were higher in males than in females, especially from April to June during the host breeding period. The level of tick infestation increased with lizard age and size. The number of ticks collected on adult lizards peaked in June and in August. Infestation levels appear to be related to lizard activity patterns and behaviour. Tick number and prevalence also varied in relation to host habitat, infestation being higher in lizards from areas with hard vegetation cover.     

Borrelia burgdorferi infection in Ixodes ricinus from habitats in Denmark

A total of 2647 ticks of the genus Ixodes was sampled by flagging the vegetation in thirty-one sites in eastern Jutland, Denmark. All ticks were identified as Ixodes ricinus Linnaeus. A total of 317 ticks (202 nymphs and 115 adults) from three different sites were examined for the spirochaete Borrelia burgdorferi Johnson et al. by indirect fluorescent antibody staining; the frequency of infection varied from 7% to 22%. It is concluded that I. ricinus, known to be the most common tick in Denmark, is the vector largely responsible for the transmission of B. burgdorferi in this country.     

Ixodes ricinus tick saliva modulates tick-borne encephalitis virus infection of dendritic cells

Tick-borne encephalitis virus is an important human pathogen, naturally delivered into host skin via a tick bite. To examine the effects of the virus on dendritic cell biology, we cultured dendritic cells with two tick-borne encephalitis virus strains of different virulence in the presence of Ixodes ricinus tick saliva. Tick saliva treatment increased proportion of virus-infected cells, led to a decrease in virus-induced TNF-α and IL-6 production and to reduced virus-induced apoptosis. Our data indicate that tick saliva modulate virus-mediated alterations in dendritic cells, thus probably being involved in the early infection process in the host.     

森林脑炎自然疫源地样本的监测及病毒的分离研究

为了解森林脑炎疫源地的分布变化趋势及样本分离病毒的特性,采集了森林脑炎高发区周边的森林全沟硬蜱、血蜱样本及森林脑炎患者的脑组织样本,用小白鼠脑内接种法检测、分离病毒分离的病毒经鉴别试验证明为森林脑炎病毒：蜱、脑两种标本检测的阳性率分别为50％和100％、结果表明森林脑炎的疫区有从林区向农业区扩散的趋势,且全沟硬蜱的带毒率较高;森脑患者的脑组织样本与蜱标本病毒的性状育差异     

Variability in cuticular hydrocarbons and phenotypic discrimination of Ixodes ricinus populations (Acarina: Ixodidae) from Europe

The cuticular hydrocarbon composition and a stepwise discriminant analysis are used to elucidate the phenotypic relationships of 66 populations of Ixodes ricinus in Europe. The method correctly allocates Ixodes persulcatus (outgroup) populations away from the main cluster of I. ricinus samples and separates the samples into ten relatively defined clusters of specimens. Populations from Poland are inseparable from samples collected in Germany, Switzerland and the Italian Alps, while individuals from Slovakia and the Czech Republic come into separate groups of phenotypic similarity. Irish and British specimens are separated but highly related and Spanish populations show an unexpectedly high distance from the remaining clusters.     

First report of Anaplasma phagocytophilum and its co-infections with Borrelia burgdorferi sensu lato in Ixodes ricinus ticks (Acari: Ixodidae) from Republic of Moldova

We examined 198 questing Ixodes ricinus ticks collected in Chisinau City, Republic of Moldova by PCR assays for Anaplasma phagocytophilum, Borrelia burgdorferi sensu lato and co-infection of both pathogens, which were detected in 9%, 25.2% and 2.5% of tested ticks, respectively. B. burgdorferi s.l. genotyping revealed the presence of five genospecies with dominance of B. garinii. Our preliminary study provides evidence about occurrence of both pathogens in this populated area, which represent a potential health risk for inhabitants.     

Diversity of Ixodes ricinus tick-associated bacterial communities from different forests

Nymphal Ixodes ricinus ticks (n=180) were collected from three different areas in the Netherlands to investigate the effect of forest composition on tick-associated microbial communities. Sampled habitats differed in thickness of leaf litter and humus layers and vegetation associations and were located near Amsterdam (Beech-Oak), Ede (Birch-Oak) and Veldhoven (Birch-Oak). Analysis of nine 16S rRNA gene clone libraries made from individual ticks showed nearest matches with presumed pathogens Candidatus Neoehrlichia mikurensis and Rickettsia australis and arthropod endosymbionts Wolbachia pipientis and Candidatus Midichloria mitochondrii. Total bacterial species diversity (Shannon index) and Borrelia species infections were determined in I. ricinus by, respectively, PCR-denaturing gradient gel-electrophoresis and PCR-reverse line blot with probes specific for Borrelia burgdorferi sensu stricto, Borrelia afzelii, Borrelia garinii, Borrelia valaisiana, Borrelia lusitaniae and Borrelia ruski. Bacterial diversity differed significantly per area and was lowest in Ede. In contrast, Borrelia species-infected ticks were more abundant in Ede, Candidatus Neoehrlichia mikurensis-infected ticks in Ede and Veldhoven, and R. australis-infected ticks in Amsterdam. Borrelia afzelii was the most common Borrelia species found in all three areas. Bacterial tick diversity was influenced by local differences in forest structure, which is proposed to modulate animal populations that are commonly parasitized by I. ricinus.     

Development of the salivary glands in embryos of Ixodes ricinus (Acari: Ixodidae)

We examined Ixodes ricinus embryos between 18 and 28 days of development with light, scanning and transmission electron microscopy. The differences in inner structure attested to establish three successive developmental stages: days 18-20, day 23, and days 26-28. Between 18 and 20 days the embryos are at early stages of organogenesis. Salivary glands cannot be identified at that stage. In 23-day-old embryos salivary glands are already outlined but the structure of alveoles is still different from that in larvae in which the embryonic development has been completed. Gland cells start to form alveoles and become active between 26 and 28 days of the development.     

The detection of rickettsia-like microorganisms within the ovaries of female Ixodes ricinus ticks

An ultrastructural study of tick-borne fever (TBF)-infected Ixodes ricinus ticks revealed the presence of rickettsia-like microorganisms within the ooplasm and the mitochondria of developing oocytes. These microorganisms are similar in appearance to the TBF agent and it is possible that although transovarial transmission of the TBF agent apparently does not occur, the rickettsiae are at least able to establish themselves in the ovaries of infected ticks.