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PubMed1995

Seasonal incidence and ecology of the tick Ixodes ricinus (Acari: Ixodidae) on grazing pastures in western France.

A longitudinal survey was carried out during a 2 year period in Western France to assess the infestation level of grazing pastures by Ixodes ricinus ticks. Four farms were visited once a month and each of the grazing pastures was sampled in the centre and at the border using the blanket dragging method. A total of 3562 I. ricinus (34 adults, 900 nymphs and 2628 larvae) were collected and the infestation was significantly higher during the first year (p < 0.0001). The infestation level by I. ricinus varied between grazing pastures and farms. Grazing pastures in the vicinity of forest were more infested than the others, all through the study. The seasonal distribution of ticks showed peaks, with low fluctuations between farms, years and stages. Tick abundance could not be related to vegetation, but only to the vicinity of woods.

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PubMed1994

Cuticular hydrocarbon composition and phenotypic variability in sympatric populations of Ixodes ricinus ticks from Poland.

Gas chromatography of cuticular hydrocarbons was used to assess genetic similarity and heterozygosity between 18 sympatric populations of adult Ixodes ricinus ticks collected from Poland. Sixteen n-alkanes, 45 monomethylalkanes, and 36 dimethylalkanes were identified. Forty-one compounds were detected in 90% of the specimens and nine hydrocarbons were present in all the specimens studied. Visual inspection of chromatograms revealed major differences in the relative abundance of hydrocarbons between populations of I. ricinus. The average proportion of heterozygotic hydrocarbons was 50.68%, while the average genetic similarity among all populations was 0.967. Two other methods were used to measure the intrapopulation variability: the number of isomeric forms for each hydrocarbon and the range of hydrocarbon abundance. It was found that some hydrocarbons manifested an unexpectedly high number of isomeric patterns, such as nonacosane (21 patterns), triacontane (23), pentacosane (26), and hexacosane (28). Our data suggest that I. ricinus ticks from Poland consist of several interbreeding, non-isolated populations, with a high degree of genetic flow between them.

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PubMed1993

The Ixodes ricinus tick as a vector of Borrelia burgdorferi in Slovenia.

In many parts of Slovenia, the vegetation, climate and animals form an ideal natural environment for the persistence of different tick species. In this study, Ixodes ricinus ticks, the prevalent tick species in our country, are identified as the vectors of Borrelia burgdorferi in Slovenia. Ticks were collected by flagging between May and October 1990. All the ticks collected from different parts of Slovenia were I. ricinus and each one was examined individually. The ticks were tested to determine the presence of B. burgdorferi by indirect immunofluorescent assay. Among the 496 ticks examined for borreliae there were 85 adults and 411 nymphs. Twenty (23.5%) adults and 18 (4.4%) nymphs were found positive for Borreliae. This study discusses the importance of I. ricinus ticks in the role of Lyme borreliosis in Slovenia.

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PubMed1989

Repetitive detection by immunoblotting of an integumental 25-kDa antigen in Ixodes ricinus and a corresponding 20-kDa antigen in Rhipicephalus appendiculatus with sera of pluriinfested mice and rabbits.

Mice were pluriinfested with nymphs and rabbits, with adult Ixodes ricinus. As determined by immunoblotting, greater than 50% of sera from these animals reacted against a tick antigen with a molecular weight of 25 kDa, which was detected in total extracts of partially fed I. ricinus females and in tick integumental extract. It was also found in engorged nymphs but was absent from larvae. Sera of I. ricinus-infested rabbits and mice or of rabbits infested with Rhipicephalus appendiculatus adults reacted with a 20-kDa antigen in total extracts of partially fed R. appendiculatus females and the integument of this species.

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PubMed1994

Borrelia burgdorferi in rodents (Apodemus flavicollis and A. sylvaticus): duration and enhancement of infectivity for Ixodes ricinus ticks.

Ixodes ricinus is an important vector of Borrelia burgdorferi in Europe, and small rodents (Apodemus flavicollis, A. sylvaticus and Clethrionomys glareolus) are important sources for infecting ticks. In this study, we examined their reservoir role by studying the duration of their infectivity for ticks. A. flavicollis and A. sylvaticus mice captured in nature were exposed to uninfected I. ricinus larvae at different times after their capture: 10 days, and 2, 7, 11, 14 and 40 months. Ticks were examined for spirochaetes after moulting using direct immunofluorescence. All animals remained infective for ticks their life long but the efficiency of transmission from hosts to ticks varied from one individual to the other, presenting a three-fold variation (26.5% to 81.4%). Rodents continously exposed to successive infestations by larval I. ricinus ticks over a period of one month showed an enhancement of infectivity for larval ticks during this period.

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PubMed1979

Passive transfer of resistance in rabbits infested with adult Ixodes ricinus L: humoral factors influence feeding and egg laying.

Parital immunity against the bites of female I. ricinus was transferred to normal rabbits by inoculating immune serum from resistant animals. Transferred humoral factors diminished the weight of the ticks' blood meal by 29% and increased the feeding period by about 1 day in comparison with ectoparasites engorged on controls. They provoked also the failure of egg laying by female I. ricinus. Only 55% of ticks fed on treated rabbits laid eggs (94% on controls). The immunological state of immune serum donors or recipients was studied and the IgG and homocytotropic specific anti-I. ricinus antibodies were identified. The immediate hypersensitivity of rabbits' skin was also controlled.

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PubMed1987

Ricinus communis agglutinin II-reactive glycoproteins from the ascites of patients with hepatocellular carcinoma and their use in enzyme-linked immunosorbent assay.

Ricinus communis agglutinin II-reactive glycoproteins from the ascites of patients with hepatocellular carcinoma were prepared using lectin affinity chromatography. Normal serum- and cirrhotic ascites-components were removed by columns with immobilized antibodies against them. Ricinus communis agglutinin II-reactive glycoproteins thus obtained were supposed to be hepatocellular carcinoma-associated and less than 0.1% of the protein in the starting material. Polyacrylamide gel electrophoresis of these glycoproteins revealed more than 10 major polypeptides with molecular weights ranging from 20K to 200K daltons. The rabbit antiserum raised against them reacted with at least three components of 45, 52 and 55K daltons. The serum level of this antibody-reactive glycoproteins was assessed by an enzyme-linked immunosorbent assay. It was elevated in 91% of cases of hepatocellular carcinoma, 70% of cases of other gastrointestinal carcinoma, 88% of cases of liver cirrhosis, 55% of cases of chronic hepatitis, and 25% of cases of acute hepatitis. The mean value of hepatocellular carcinoma was significantly greater than those of other groups. These results suggest that some of Ricinus communis agglutinin II-reactive glycoproteins in hepatocellular carcinoma patients may be cancer-associated glycoproteins and that their serum levels are increased in hepatocellular carcinoma patients.

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PubMed1998

Expression of outer surface proteins A and C of Borrelia burgdorferi in Ixodes ricinus ticks removed from humans.

A total of 131 Ixodes ricinus (51 females, 1 male and 79 nymphs) removed from persons living in Southern Germany were investigated by immunofluorescence assay for the presence of Borrelia burgdorferi with a polyvalent rabbit immune serum and monoclonal antibodies specific for outer surface proteins (Osp) A or C. Borreliae were detectable in 48 (36.6%) of the ticks. Infection rates of these adults and nymphs were significantly higher than infection rates of unfed ticks from Southern Germany. Borreliae in 31.3% (n=15) of the infected ticks expressed solely OspA, solely OspC in 12.5% (n=6), and both OspA and OspC in 39.6% (n=19) of ticks, while in 16.7% (n=8) of ticks neither were expressed. Presentation of OspC by B. burgdorferi in I. ricinus was correlated with tick weight: in females, OspC was detectable only in ticks with a minimum weight of about 3.5 mg, and in nymphs weighing at least 1 mg. These results indicate that in I. ricinus removed from humans OspC is up-regulated during the blood meal of the tick, but in most ticks OspA is still detectable and might even be present in the absence of OspC expression in the midgut and salivary glands of nearly fully engorged nymphal ticks. Furthermore, we found strong evidence that borreliae expressing solely OspA while in the salivary glands can cause Lyme borreliosis. Our findings indicate that during tick feeding, humans are exposed to borreliae that may express either OspA or OspC or both, or lack both OspA and C. These findings suggests that, at the minimum, both OspA and C should be considered as vaccine candidates for prophylaxis of Lyme borreliosis in Europe.

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PubMed1996

Ultrastructural localization of a sialic acid-specific hemolymph lectin in the hemocytes and other tissues of the hard tick Ixodes ricinus (Acari; Chelicerata).

Lectins have been suggested to function as pattern-recognition molecules in invertebrate immune mechanisms. A lectin from the hemolymph of the tick Ixodes ricinus with main specificity for sialic acid was characterized and antibodies directed against this lectin were prepared. In this study, these antibodies were used to localize the lectin in the tissues of I. ricinus. Immunoreactivity with poly- and monoclonal antibodies was detected in the granules of both types of granular hemocytes, at the membrane of hemocytes, and at the basal laminae surrounding the hemocoel. Furthermore, cells attached to the midgut, invaginations of Géné's organ, and granular inclusions of nephrocytes were labeled. The immunoreactivity detected in hemocytes and the hemocoel lining supports the idea that the hemolymph lectin may function as a recognition molecule in the immune system of I. ricinus. Another function could be protection of eggs that are coated with secretions by Géné's organ. The lectin activity could also be involved in transmission of Borrelia burgdorferi, the causative agent of Lyme borreliosis, and the tick-borne encephalitis virus.

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PubMed1996

Mitotic activity of the hemocytes in the tick Ixodes ricinus (Acari; Ixodidae).

The blood cells, or hemocytes, of Ixodes ricinus have been shown to recognize, attack, and phagocytose microorganisms invading the body cavity, or hemocoel, of this tick. Regulated proliferation and differentiation of hemocytes, also referred to as immunocytes, is basic to an effective immune response to invading microorganisms. Therefore, this study dealt with hemopoiesis in I. ricinus, the vector tick of the Lyme disease spirochete Borrelia burgdorferi. Histological evidence for the presence of hemopoietic tissue, a preferential proliferation site of hemocytes, is presented. Mainly the mitotic activity of free-floating hemocytes was examined. By means of microscopical photometry and flow cytometry, all three types of hemocytes in engorging female I. ricinus were found in different stages of the cell cycle. In the engorging tick, up to 40% of the hemocytes counted were in the S phase or the G2/M phase. From this study we conclude that the differentiated hemocyte types do not differentiate from stem cells in the adult tick. Moreover, microorganisms entering the hemocoel of engorging ticks are confronted with high numbers of hemocytes and, therefore, with an effective cellular immune response.

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PubMed2006

Prevalence of Borrelia burgdorferi sensu lato in the tick Ixodes ricinus in the Styrian mountains of Austria.

A total of 691 Ixodes ricinus (22 male, 39 female, 501 nymphs and 129 larvae), the tick vector of Lyme borreliosis, were collected by flagging from vegetation in 11 areas at altitudes between 789 m and 1350 m above sea level in mixed woodland with pasture land (cattle) in the province of Styria in Austria. The ticks were individually examined for presence of Borrelia burgdorferi sensu lato by dark-field microscopy and 107 of them by real-time PCR. Attempts to cultivate borreliae were made in BSK-H medium. The overall positivity rate of all collected ticks (excepting larvae) was 10.9%: 9.1% in males, 17.9% in females and 10.4% in nymphs. The 129 larvae examined showed no presence of B. burgdorferi s.l. The mean infection rate of I. ricinus collected at the highest altitude in this study, Gaberl at 1350 m a.s.l.--and at the same time the highest one reported in Europe--was 6.4%: 1/9 males, 2/18 females and 6/114 (5.3%) nymphs were positive. Culture attempts were positive in 12 cases and species identification showed eight isolates were B. afzelii and four B. garinii. Three additional positive results found by PCR (negative by culture) were identified twice as B. afzelii and once as B. garinii. This study shows that the risk of acquiring Lyme borreliosis in habitats at higher altitudes is limited, because of the lower density of I. ricinus and its lesser infection rate than at lower altitudes in central Europe, but nevertheless the risk does exist.

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PubMed2005

Ontogeny of tick hemocytes: a comparative analysis of Ixodes ricinus and Ornithodoros moubata.

Hemocytes of two tick species, Ixodes ricinus and Ornithodoros moubata, were investigated with the aim to determine their ultrastructural characteristics and developmental relationships. Only a limited number of ultrastructural features was shown to be unequivocally homological across all hemocyte types. The two species, representing distant groups of ticks, differ in the composition of their circular cell populations. In I. ricinus, three groups of distinct morphological types of hemocytes could be determined according to well-defined ultrastructural features: a typical non-phagocytic granular cell with electron-dense granula and homogeneous cytoplasm (Gr II), and two different types of phagocytic hemocytes, namely plasmatocytes with a low number of granula and phagocytic granolocytes, designated as Gr I. In contrast, an additional cell type resembling insect spherulocytes was determined in O. moubata. This cell type does not seem to be homologous to any I. ricinus hemocyte and may represent a cell type typical of soft ticks only. Possible ontogenetic lineages of the hemocytes of both tick-species were inferred.

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PubMed2006

Genetic variation of ticks (Ixodes ricinus L.) in the Lithuanian and Norwegian populations.

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 within Kretinga (Lithuania) and Odderoya (Norway) populations situated in coastal areas where many migratory and sea birds are aggregated.

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PubMed1986

A computer simulation of the effects of specific environmental factors on the development of the sheep tick Ixodes ricinus L.

A previously developed technique for predicting field development rates of the tick, Ixodes ricinus, has been modified and used in an attempt to test interpretations of field data and to gain further insight into the population dynamics of I. ricinus. The results of this study have provided encouraging evidence of the validity of the predictive technique, identified certain areas in the biology of I. ricinus which require further investigation and, in general, supported the suggestion that in Ireland a continuous interchange of ticks between spring and autumn populations occurs. This technique requires further refinement but it appears to have considerable potential for predicting the behaviour of tick populations in different localities and under the influence of different weather conditions.

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PubMed2006

Prevalence of Borrelia burgdorferi s.l. OspA types in Ixodes ricinus ticks from selected localities in Slovakia and Poland.

In this study, 746 questing Ixodes (I.) ricinus ticks from eastern Slovakia and 187 ticks from southern Poland were investigated for infection with Borrelia (B.) burgdorferi sensu lato and different outer surface protein A (OspA) types by an improved restriction fragment length polymorphism (RFLP) analysis of the ospA gene. The method enables differentiation of both single and multiple infections with B. burgdorferi s.s. (OspA type 1), B. afzelii (OspA type 2), B. garinii (OspA types 3-8), B. valaisiana (subgroups I and II), B. lusitaniae, B. bissettii, and the recently described genospecies A14S. Broad heterogeneity in B. burgdorferi s.l. was found including all species and subtypes except for B. lusitaniae, B. bissettii, and genospecies A14S. Regional prevalence of B. burgdorferi s.l. varied between 8% and 22.5%. The most frequent species were B. garinii (45.4%) and, notably, B. burgdorferi s.s. (31.3%). I. ricinus nymphs harbored almost exclusively B. burgdorferi s.s. and B. garinii OspA type 4, while in adults a broad variety of B. burgdorferi s.l. types was found. Mixed infections were significantly more often in nymphs than in adult ticks. In all mixed infected nymphs, B. burgdorferi s.s. with OspA type 4 was present. These data strongly suggest that B. burgdorferi s.s. and B. garinii OspA type 4 are maintained in these areas by specific transmission cycles involving a so far undetermined vertebrate host which is frequently fed on by I. ricinus larvae. This improved method provides a reliable tool for epidemiological studies on the heterogeneity of B. burgdorferi species and OspA types, an important prerequisite for improved local risk assessment and for test- and vaccine development for Europe.

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PubMed2006

Babesia microti: prevalence in wild rodents and Ixodes ricinus ticks from the Mazury Lakes District of North-Eastern Poland.

Infections of Babesia microti (Apicomplexa, Piroplasmida), a common erythroparasitic protozoon of Holarctic rodents, are not widely acknowledged in Poland. The presence of this parasite in various species of wild rodents has been well documented throughout the northern temperate zone of North America, Europe, and Eurasia. However, human babesiosis attributable to infection with B. microti has been reported only from the north-eastern and upper midwestern United States and Japan. We recently carried out an epizootiological survey investigating the prevalence of B. microti both in the tick Ixodes ricinus and in wild rodents in North-Eastern Poland. Blood samples were collected from a total of 483 animals comprising three species: Apodemus flavicollis, Microtus arvalis, and Microtus oeconomus trapped at Urwitałt near Mikołajki in the Mazury Lakes District. Questing adult I. ricinus ticks were collected in the study sites by blanket dragging of vegetation in heterogeneous, deciduous woodland, and, in addition, rodents were carefully examined for feeding larvae and nymphs. Altogether, B. microti was detected in 9 out of 1513 I. ricinus ticks (0.6%) examined by PCR. This included 163 adults (92 females and 71 males), 50 nymphs, and 1300 larvae 3%, 8%, and 0% of which were PCR-positive, respectively. Of 85 A. flavicollis, 374 M. arvalis and 24 M. oeconomus, 1%, 12.8%, and 42% were parasitaemic, respectively, as determined by microscopic examination of blood smears stained with Giemsa. B. microti DNA, extracted from 53 M. arvalis and 5 M. oeconomus and examined by nested PCR, targeting a piroplasm-specific portion of the 18S ribosomal DNA, revealed 72% and 40%, respectively, to be PCR positive. Sequence analysis showed that all PCR-positive samples had rDNA sequences identical (100% homology) to that of the Munich B. microti strain isolated from Mus musculus. The results of this study indicate that the B. microti commonly encountered among Microtus spp. rodents is probably not a zoonotic strain and, therefore, that it is most unlikely to represent a risk to public health in the Mazury Lakes District of North-Eastern Poland.

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PubMed2006

A comparison of Chryseobacterium indologenes pathogenicity to the soft tick Ornithodoros moubata and hard tick Ixodes ricinus.

A yellow-pigmented Gram-negative bacterium, Chryseobacterium indologenes, was found in the gut contents of about 65% of soft ticks Ornithodoros moubata from a perishing laboratory colony. The isolated putative pathogen, C. indologenes, was susceptible to cotrimoxazol and addition of this antibiotic (Biseptol 480) to the blood meal significantly decreased the tick mortality rate. The artificial infection of healthy O. moubata by membrane feeding on blood contaminated with C. indologenes was lethal to all ticks at concentrations 10(6) bacteria/ml. On the contrary, a similar infection dose applied to the hard tick Ixodes ricinus by capillary feeding did not cause significant mortality. Examination of guts dissected from infected O. moubata and I. ricinus revealed that C. indologenes was exponentially multiplied in the soft tick but were completely cleared from the gut of the hard ticks within 1 day. In both tick species, C. indologenes were found to penetrate from the gut into the hemocoel. The phagocytic activity of hemocytes from both tick species was tested by intrahaemocoelic microinjection of C. indologenes and evaluated by indirect fluorescent microscopy using antibodies raised against whole bacteria. Hemocytes from both tick species displayed significant phagocytic activity against C. indologenes. All O. moubata injected with C. indologenes died within 3 days, whereas the increase of the mortality rate of I. ricinus was insignificant. Our results indicate that hard ticks possess much more efficient defense system against infection with C. indologenes than the soft ticks. Thus, C. indologenes infection has the potential to be a relevant comparative model for the study of tick immune reactions to transmitted pathogens.

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PubMed2004

A symbiont of the tick Ixodes ricinus invades and consumes mitochondria in a mode similar to that of the parasitic bacterium Bdellovibrio bacteriovorus.

We have recently performed molecular characterisation of an intracellular alpha-proteobacterium, named IricES1, which resides in the ovarian tissue of female Ixodes ricinus ticks from Italy. A unique characteristic of this bacterium is its ability to invade the mitochondria of the cells in which it resides. Although some ultrastructural studies have been performed on close relatives of this bacterium from I. ricinus in England and Switzerland, a number of questions remain about its movement within ovarian tissues and mitochondria. We have performed the first detailed ultrastructural examination of IricES1 in engorged female adult I. ricinus. Among our findings was that the bacterium enters mitochondria in a similar way to that employed by the 'predatory' bacterium Bdellovibro bacteriovorus, that is, between the inner and outer membranes. It then appears to multiply, with the new 'colony' consuming the mitochondrial matrix. Despite having many of their mitochondria consumed, oocytes appear to develop normally, and the bacteria are likely to be vertically transferred to all eggs.

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