Ixodes

Abstract: RAPD markers were used to measure the genetic diversity of 119 individuals of Ixodes ricinus collected from Lithuania and Norway. The samples were analysed within and also between the populations. We analysed 74 loci in each of 6 populations. Our results show high levels of diversity within the populations. The percentage of polymorphic loci of the six analysed populations: Birzai, Vilnius, Kretinga, Tjore, Kjosvik and Odderoya were 68.9%, 58.1%, 78.38%, 62.2%, 44.6 % and 68.9%, respectively. The percentage of polymorphic loci in the Lithuanian populations was 93.2%, and in the Norwegian populations 81.08%. The genetic distance ranged from 0.019 to 0.079 within Norwegian populations and from 0.005 to 0.0967 within Lithuanian populations and between the countries from 0.022 to 0.146. The genetic variation of I. ricinus among Norwegian populations was lower than among Lithuanian populations. The highest part of genetic variation in I. ricinus ticks depends on variation withi...

Ticks transmit important pathogens affecting cattle such as intracellular bacteria of the genus Anaplasma or protozoa of the order Piroplasmida. This study aimed at assessing tick species present on pastures and cattle and determining occurrence of the tick-borne pathogens Anaplasma phagocytophilum and Babesia spp. in cattle. During May and June 2013, ticks and EDTA blood were collected from 185 dairy cows at six locations in Serbia. Ticks were also collected directly from the pastures at four of these locations. The occurrence of A. phagocytophilum was investigated by serological (immunofluorescence antibody test (IFAT)) and molecular methods (real-time PCR) and of piroplasms by traditional PCR followed by sequencing. The most prevalent tick species on animals was Ixodes ricinus, (n = 167), followed by Haemaphysalis punctata (n = 146) and Dermacentor marginatus (n = 122). On the pasture, however, the most common species was H. punctata (n = 41), I. ricinus (n = 37), and D. marginat...

The paper describes estimating the tick-born encephalitis incidence rate by meteorological data using linear regression method. The study shows 2 models of TBE incidence. First one describes general dependency between temperatures and TBE incidence (1972-2004). The second one (1994-2004) tries to find out more specific characteristics.

The castor bean tick (Ixodes ricinus) transmits infectious diseases such as Lyme borreliosis, which constitutes an important ecosystem disservice. Despite many local studies, a comprehensive understanding of the key drivers of tick abundance at the continental scale is still lacking. We analyze a large set of environmental factors as potential drivers of I. ricinus abundance. Our multi-scale study was carried out in deciduous forest fragments dispersed within two contrasting rural landscapes of eight regions, along a macroclimatic gradient stretching from southern France to central Sweden and Estonia. We surveyed the abundance of I. ricinus, plant community composition, forest structure and soil properties and compiled data on landscape structure, macroclimate and habitat properties. We used linear mixed models to analyze patterns and derived the relative importance of the significant drivers. Many drivers had, on their own, either a moderate or small explanatory value for the abund...

Anaplasma marginale, a tick-borne rickettsial pathogen of cattle, infects bovine erythrocytes, resulting in mild to severe hemolytic disease that causes economic losses in domestic livestock worldwide. Recently, the Virginia isolate of A. marginale was propagated in a continuous tick cell line, IDE8, derived from embryonic Ixodes scapularis. Development of A. marginale in cell culture was morphologically similar to that described previously in ticks. In order to evaluate the potential of the cell culture-derived organisms for use in future research or as an antigen for serologic tests and vaccines, the extent of structural conservation of the major surface proteins (MSPs) between the cell culture-derived A. marginale and the bovine erythrocytic stage, currently the source of A. marginale antigen, was determined. Structural conservation on the tick salivary-gland stage was also examined. Monoclonal and monospecific antisera against MSPs 1 through 5, initially characterized against er...

Vector-borne diseases are exceptionally sensitive to climate change. Predicting vector occurrence in specific regions is a challenge that disease control programs must meet in order to plan and execute control interventions and climate change adaptation measures. Recently, an increasing number of scientific articles have applied ecological niche modelling (ENM) to study medically important insects and ticks. With a myriad of available methods, it is challenging to interpret their results. Here we review the future projections of disease vectors produced by ENM, and assess their trends and limitations. Tropical regions are currently occupied by many vector species; but future projections indicate poleward expansions of suitable climates for their occurrence and, therefore, entomological surveillance must be continuously done in areas projected to become suitable. The most commonly applied methods were the maximum entropy algorithm, generalized linear models, the genetic algorithm for rule set prediction, and discriminant analysis. Lack of consideration of the full-known current distribution of the target species on models with future projections has led to questionable predictions. We conclude that there is no ideal 'gold standard' method to model vector distributions; researchers are encouraged to test different methods for the same data. Such practice is becoming common in the field of ENM, but still lags behind in studies of disease vectors.

Ixodes ricinus ticks are vectors of numerous human and animal pathogens. They are host generalists able to feed on more than 300 vertebrate species. The prevalence of tick-borne pathogens is influenced by host-vector-pathogen interactions that results in spatial distribution of infection risk. Broad-range polymerase chain reaction electrospray ionization mass spectrometry (PCR/ESI-MS) was used to analyze 435 I. ricinus nymphs from four localities in the south of the Czech Republic for the species identification of tick-borne pathogens. Borrelia burgdorferi sensu lato spirochetes were the most common pathogen detected in the ticks; 21% of ticks were positive for a single genospecies and 2% were co-infected with two genospecies. Other tick-borne pathogens detected included Rickettsia helvetica (3.9%), R. monacensis (0.2%), Anaplasma phagocytophilum (2.8%), Babesia venatorum (0.9%), and Ba. microti (0.5%). The vertebrate host of the ticks was determined using PCR followed by reverse li...

Cyclic dimeric GMP (c-di-GMP) is a bacterial second messenger that modulates many biological processes. Although its role in bacterial pathogenesis during mammalian infection has been documented, the role of c-di-GMP in a pathogen's life cycle within a vector host is less understood. The enzootic cycle of the Lyme disease pathogen Borrelia burgdorferi involves both a mammalian host and an Ixodes tick vector. The B. burgdorferi genome encodes a single copy of the diguanylate cyclase gene (rrp1), which is responsible for c-di-GMP synthesis. To determine the role of c-di-GMP in the life cycle of B. burgdorferi, an Rrp1-deficient B. burgdorferi strain was generated. The rrp1 mutant remains infectious in the mammalian host but cannot survive in the tick vector. Microarray analyses revealed that expression of a four-gene operon involved in glycerol transport and metabolism, bb0240-bb0243, was significantly downregulated by abrogation of Rrp1. In vitro, the rrp1 mutant is impaired in g...

The European hedgehog (Erinaceus europaeus) is known to host several ectoparasites and also tick-borne pathogens, but there is scant information on its eastern relative, the Northern white-breasted hedgehog (Erinaceus roumanicus). We have studied ...

Rapid and sensitive detection of resistance to insecticides in arthropods is needed. In the cattle tick. Boophilus microplus, resistance to a variety of acaricides is widespread. The most commonly used assay for resistance, the larval packet test, takes at least two, but generally six weeks for a one-host tick like B. microplus to complete and may take up to three months to complete for three-host ticks. Here we describe a test for resistance to organophosphate acaricides that can be used on larvae and adult ticks which takes less than 24 hours. The test measures the difference in acetylcholinesterase (AChE) activity in homogenates of ticks in the presence and absence of propoxur, a carbamate acaricide. We found clear discrimination of organophosphate-susceptible and organophosphate-resistant adults with 100 microM propoxur. AChE from susceptible ticks had almost no activity at this concentration of propoxur whereas AChE from resistant ticks had 67% of its potential activity. AChE f...

Transmission from the vertebrate host to the arthropod vector is a critical step in the life-cycle of any vector-borne pathogen. How the probability of host-to-vector transmission changes over the duration of the infection is an important predictor of pathogen fitness. The Lyme disease pathogen Borrelia afzelii is transmitted by Ixodes ricinus ticks and establishes a chronic infection inside rodent reservoir hosts. The present study compares the temporal pattern of host-to-tick transmission between two strains of B. afzelii. Laboratory mice were experimentally infected via tick bite with one of two strains of B. afzelii: A3 and A10. Mice were repeatedly infested with pathogen-free larval Ixodes ricinus ticks over a period of 4 months. Engorged larval ticks moulted into nymphal ticks that were tested for infection with B. afzelii using qPCR. The proportion of infected nymphs was used to characterize the pattern of host-to-tick transmission over time. Both strains of B. afzelii follow...

Borrelia miyamotoi, a relapsing fever spirochete, has been found recently in Ixodes ricinus ticks; however, little is known about its spatial distribution and potential local impact on human health. A total of 640 ticks (447 nymphs and 193 adults) collected throughout Portugal were analyzed using two nested PCR protocols, one targeting the flagellin gene and the other the internal transcribed space region between the 5S and the 23S rRNA. As a result, B. miyamotoi was detected, for the first time, in one guesting I. ricinus nymph collected in the Lisboa district. In addition, a prevalence of 11% (71/640) for B. burgdorferi sensu lato was obtained. Even though no human relapsing fever cases due to infection by B. miyamotoi have been reported yet in Portugal, surveillance must be improved to provide better insight into the prevalence and distribution of this spirochete in ticks.

Lyme borreliosis is the most common zoonotic disease transmitted by ticks in Europe and North America. Despite having multiple tick vectors, the causative agent Borrelia burgdorferi sensu lato, is vectored mainly by Ixodes ricinus in Europe. In the present study, we aimed to review and summarize the existing data published from 2010 to 2016 concerning the prevalence of B. burgdorferi s.l. spirochetes in questing I. ricinus The primary focus was to evaluate the infection rate of these bacteria in ticks, accounting for tick stage, adult tick gender, region and detection method, as well as to investigate any changes in prevalence over time. The obtained data was compared to findings of a previous meta-study. The literature search identified data from 24 countries with 115,028 ticks in total inspected for infection with B. burgdorferi s.l. We showed that the infection rate was significantly higher in adults than in nymphs and in females than in males. We found significant differences be...

Anaplasma phagocytophilum is a worldwide distributed bacterium with a significant medical and veterinary importance. It grows within the phagosome of infected neutrophils and is responsible for human granulocytic anaplasmosis (HGA), tick-borne fever (TBF) of small ruminants and cattle, canine and equine granulocytic anaplasmosis, but infects also a great variety of wildlife species. Wild ungulates and rodents are considered reservoirs of infection in natural foci. The objective of this study was to determine the spectrum of animal species involved in the circulation of A. phagocytophilum in Slovakia and to analyze the variability of obtained nucleotide sequences, in order to determine whether genotypes from Slovakia cluster according to host-species or geographical location. Several animal species and vector ticks were screened for the presence of members of the family Anaplasmataceae using PCR based methods. Additional data on the molecular evidence of Anaplasma ovis and Candidatus Neoehrlichia mikurensis are presented. These pathogens were detected in tested sheep flocks and rodents with the mean infection rates of 8.16% and 10.75%, respectively. A. phagocytophilum was genotyped by 16S rRNA and groEL gene sequencing. Bacterial DNA was confirmed in questing ixodid ticks, in domesticated canine, wild rodents and several species of wild ungulates. In European isolates, 16S rRNA gene does not seem to be an appropriate locus for the analyses of heterogeneity as it is too conservative. Similarly, 16S rRNA isolates from our study did not reveal any polymorphisms. All isolates were identical in overlapped region and showed identity with sequences from ticks, horses or ruminants previously isolated elsewhere in the world. On the other hand, the groESL heat shock operon is widely used for determination of diversity and the analyses have already revealed considerable degree of heterogeneity. Tested ungulates were infected with A. phagocytophilum to a considerable extent. High proportions of red and roe deer tested positive and the rates of infection reached over 60.0%. GroEL sequences from canine, wild ungulates and ticks from Slovakia clustered within a clade together with isolates from horses, humans, wild ungulates and ticks from Slovakia or elsewhere in the world. Sequences from rodents clustered apart from those obtained from wild ungulates, ticks and humans. These results suggest that European rodents do not harbour A. phagocytophilum strains with strong zoonotic potential such as those from United States.

Ixodes ricinus is the main tick vector of the microbes that cause Lyme disease and tick-borne encephalitis in Europe. Pathogens transmitted by ticks have to overcome innate immunity barriers present in tick tissues, including midgut, salivary glands epithelia and the hemocoel. Molecularly, invertebrate immunity is initiated when pathogen recognition molecules trigger serum or cellular signalling cascades leading to the production of antimicrobials, pathogen opsonization and phagocytosis. We presently aimed at identifying hemocyte transcripts from semi-engorged female I. ricinus ticks by mass sequencing a hemocyte cDNA library and annotating immune-related transcripts based on their hemocyte abundance as well as their ubiquitous distribution. De novo assembly of 926,596 pyrosequence reads plus 49,328,982 Illumina reads (148 nt length) from a hemocyte library, together with over 189 million Illumina reads from salivary gland and midgut libraries, generated 15,716 extracted coding sequ...

A novel bacterium that infects laboratory rats was isolated from wild Rattus norvegicus rats in Japan. Transmission electron microscopy of the spleen tissue revealed small cocci surrounded by an inner membrane and a thin, rippled outer membrane in a membrane-bound inclusion within the cytoplasm of endothelial cells. Phylogenetic analysis of the 16S rRNA gene sequence of the bacterium found in R. norvegicus rats and Ixodes ovatus ticks in Japan revealed that the organism represents a novel clade in the family Anaplasmataceae, which includes the Schotti variant found in Ixodes ricinus ticks in the Netherlands and the Ehrlichia-like Rattus strain found in R. norvegicus rats from China. The novel clade was confirmed by phylogenetic analysis of groESL sequences found in R. norvegicus rats and Ixodes ovatus ticks in Japan. No serological cross-reactivity was detected between this bacterium and members of the genera Anaplasma, Ehrlichia or Neorickettsia in the family Anaplasmataceae. It is...

Ixodes scapularis is the principle vector of Lyme disease in the East coast and upper Midwest regions of the United States, yet the tick is also present in the Southeast, where Lyme disease is absent or rare. A closely related species, I. affinis also carries the pathogen in the South but does not seem to transmit to humans. In order to better understand the geographic diversity of the tick, we analyzed the microbiota of 104 adult I. scapularis and 13 adult I. affinis ticks captured in 19 locations in South Carolina, North Carolina, Virginia, Connecticut and New York. Initially ticks from 4 sites were analyzed by 454-pyrosequencing. Subsequently, ticks from these sites plus 15 others were analyzed by Illumina MiSeq. By both analyses female tick microbiomes were significantly less diverse than those of male ticks. The dissimilarity between tick microbiomes increased with distance between sites and the state in which a tick was collected could be inferred from its microbiota. The genu...

Aeromonas veronii is a gram-negative pathogen capable of infecting both fish and mammals, including humans, and natural infection in fish results in irreparable damage to the aquaculture industry. Lactic acid bacteria (LAB) have a number of properties that make them attractive candidates as delivery vehicles for presentation to the mucosa sites of compounds with pharmaceutical interest, in particular vaccines. In this study, we generated two recombinant Lactobacillus casei (surface-displayed or secretory) expressing the OmpAI of A.veronii and evaluated the effect on immune responses in fish model. A 1022 bp gene fragment of the 42 kDa OmpAI antigen of A.veronii was cloned into pPG-1 (surface-displayed) and pPG-2 (secretory) and electrotransformed into Lactobacillus casei CC16. The recombinant plasmid in L.casei could be stably inherited over 50 generations, and production of OmpAI protein had slight limited effects on cells growth. Treatment of common carp with the recombinant vacci...