Showing papers on "Ixodes ricinus published in 1996"
TL;DR: The results indicate that the local skin site of tick feeding is an important focus of viral replication early after TBE virus transmission by ticks, and supports the hypothesis that viremia is a product, rather than a prerequisite, of tick-borne virus transmission.
194 citations
TL;DR: Results suggest that a cofeeding transmission occurred between B. burgdorferi-infected ticks and noninfected ones in the absence of a disseminated infection, and the mechanism responsible is being undertaken to determine whether the mechanism is similar to that described previously with virus-infecting ticks.
Abstract: Feeding ticks are generally spatially distributed in clusters on vertebrate hosts To test the effect of clustering on transmission of a tick-borne pathogen, Borrelia burgdorferi Johnson, Schmid, Hyde, Steigerwalt & Brenner-infected Ixodes ricinus L nymphs and uninfected I ricinus larvae were allowed to feed together in retaining chambers on uninfected AKR/N mice Engorged infective nymphs dropped off at days 5, 6, and 7, and the 1st infected larvae that fed in the chambers together with the infected nymphs dropped off at day 5 In contrast, ear biopsies and xenodiagnostic larvae placed on the head remained negative during that period These results suggest that a cofeeding transmission occurred between B burgdorferi-infected ticks and noninfected ones in the absence of a disseminated infection Further investigations are being undertaken to determine whether the mechanism responsible for this cofeeding transmission is similar to that described previously with virus-infected ticks
194 citations
TL;DR: The occurrence of group VS116 in northern Croatia and in an earlier study in The Netherlands, infers that this genomic group may be well established in EuropeanI.
Abstract: We investigated the presence ofBorrelia burgdorferi sensu lato inIxodes ricinus ticks collected in a Lyme borreliosis (LB) endemic region of northern Croatia. Ticks (n=124) were collected at five locations and analysed by the polymerase chain reaction (PCR). A DNA fragment from the internal transcribed spacer (ITS2) ofI. ricinus was detected in all tick lysates, indicating that PCR inhibitors were not present.Borrelia burgdorferi sensu lato DNA was detected in 56 out of 124 ticks (45%). Four genomic groups were identified:Borrelia afzelii (n=26),Borrelia garinii (n=5), group VS116 (n=5) andB. burgdorferi sensu stricto (n=1). Mixed infections ofB. afzelii with group VS116 (n=10) andB. afzelii withB. burgdorferi sensu stricto (n=1) were also detected. Eight ticks containedB. burgdorferi sensu lato, which could not be typed. The detection ofB. afzelii andB. garinii in ticks was in agreement with manifestations of LB found locally. The occurrence of group VS116 in northern Croatia and in an earlier study in The Netherlands, infers that this genomic group may be well established in EuropeanI. ricinus.
172 citations
TL;DR: The efficacy of the mitochondrially encoded cytochrome b gene as a molecular marker for the discrimination of the reservoir host species of the Lyme borreliosis spirochete, Borrelia burgdorferi sensu lato, in its European vector Ixodes ricinus was determined.
Abstract: The efficacy of the mitochondrially encoded cytochrome b gene as a molecular marker for the discrimination of the reservoir host species of the Lyme borreliosis spirochete, Borrelia burgdorferi sensu lato (s.l.), in its European vector Ixodes ricinus (Acari: Ixodidae) was determined. Degenerate PCR primers were designed which amplified orthologous regions of the cytochrome b gene in several animal species which act as B. burgdorferi s.l. reservoirs and hosts for I. ricinus. PCR products were amplified and characterized by hybridization and restriction fragment length polymorphism analysis. Restriction fragment length polymorphism analysis of a 638-bp PCR product with HaeIII and DdeI revealed unique restriction fragment profiles, which allowed the taxonomic identification of animals to the genus level. A system was devised for the detection of the larval host blood meal from the remnants in unfed nymphal I. ricinus ticks by nested PCR amplification. An inverse correlation was demonstrated between amplicon size and successful PCR amplification of host DNA from the nymphal stage of the tick. The stability of the cytochrome b product as a marker for the identification of the larval host species in the nymphal instar was demonstrated up to 200 days after larval ingestion (approximately 165 days after molting) by reverse line blotting with a host-specific probe. This assay has the potential for the determination of the reservoir hosts of B. burgdorferi s.l. by using extracts from the same individual ticks for both the identification of the host species and the detection of the Lyme borreliosis spirochete.
102 citations
TL;DR: It is suggested that reservoir-incompetent cervids, being more important hosts for adult 1.
Abstract: During 1994-1995 we examined the density of questing Ixodes ricinus (L.) nymphs and their prevalence of infection with Borrelia-like spirochetes at 43 localities in south-central Sweden with median nymphal densities ranging from 0.1 to > 50/100 m2. The general pattern was that the infection prevalence in nymphs increased with nymphal density at 35 nymphs per 100 m2) at the small island of Bedaron was most likely related to the presence of large numbers of fallow deer, Dama dama (L.), which are reservoir-incompetent for Borrelia burgdorferi s.l. Johnson, Schmid, Hyde, Steigerwalt & Brenner. However, because the increase in nymphal density at Bedaron was greater than the decrease in infection prevalence, 5 of the 6 highest densities of infected nymphs occurred in the 5 localities at Bedaron. We suggest that reservoir-incompetent cervids, being more important hosts for adult 1. ricinus than for the larvae, indirectly increase the density of infected nymphal ticks by feeding large numbers of adult ticks, thereby increasing the number of larvae feeding on reservoir-competent shrews, rodents, and hares.
85 citations
TL;DR: In May 1995, 61 Ixodes ricinus larvae were collected from vegetation on the Dutch North Sea island of Ameland and hybridization of the PCR product to genomic group-specific probes revealed that two larvae were infected with Borrelia afzelii and group VS116, respectively and one larval tick carried a mixed infection of B. afzelius and Borrelian.
Abstract: In May 1995, 61 Ixodes ricinus larvae were collected from vegetation on the Dutch North Sea island of Ameland. Fifty-seven lysates (94%) were analysed for the presence of Borrelia DNA by the polymerase chain reaction (PCR), which amplified the intergenic spacer region between the 5S and 23S rRNA genes. Three samples (5%) were positive and hybridization of the PCR product to genomic group-specific probes revealed that two larvae were infected with Borrelia afzelii and group VS116, respectively and one larval tick carried a mixed infection of B. afzelii and Borrelia garinii. Previously, we showed that these three genomic groups were present in adult and nymphal ticks collected on Ameland. Transovarial transmission may be an important factor in the establishment of these genomic groups in the local tick population.
76 citations
TL;DR: Monitoring of D.reticulatus for F.tularensis seems to be a very efficient approach in the surveillance of tularaemia in the flood‐plain forest ecosystems of Europe.
Abstract: . A total of 924 questing Dermacentor reticulatus (Fabricius), 504 Ixodes ricinus (L.), sixty Haemaphysalis concinna Koch and 718 mosquitoes (Aedes spp.) were examined in a floodplain forest ecosystem during the 1994-95 outbreak of tularaemia in South Moravia, Czech Republic. Francisella tularensis was not isolated from H.concinna ticks or Aedes spp. mosquitoes, whereas twenty-one isolates were recovered from the other haematophagous arthropods. Dermacentor reticulatus revealed a significantly higher infection rate (2.6%) than I.ricinus (0.2%). This tick species acts as principal vector for tularaemia in the enzootic focus. Monitoring of D.reticulatus for F.tularensis thus seems to be a very efficient approach in the surveillance of tularaemia in the flood-plain forest ecosystems of Europe.
68 citations
TL;DR: A total of 4803 domestic and wild animals which were presented for examination at a veterinary clinic in north Baden, Germany over a period of 1 year were examined for tick infestation, finding 434 nymphal and adult ticks found belonged to the species Ixodes ricinus, IxODE hexagonus, and Ixode ventalloi.
51 citations
TL;DR: The seasonal pattern of prevalence of Borrelia infection in questing nymphs was similar during all 3 yr, with a peak infection prevalence in late spring or early summer, followed by lower infection prevalences in late summer and autumn.
Abstract: Seasonal variations in the density of questing Ixodes ricinus (L.) nymphs and their prevalence of infection with Borrelia burgdorferi s.l. Johnson, Schmid, Hyde, Steigerwalt & Brenner were studied during 1991-1993 at a locality in southcentral Sweden. The seasonal pattern of the density of questing I. ricinus nymphs was variable; there was a bimodal pattern with peaks of similar magnitude in 1991, a bimodal pattern with a small spring peak and a greater autumn peak in 1992, and a unimodal pattern with a spring peak and lower values during summer and autumn in 1993. The seasonal pattern of prevalence of Borrelia infection in questing nymphs was similar during all 3 yr, with a peak infection prevalence in late spring or early summer, followed by lower infection prevalences in late summer and autumn. There was a significant correlation between the monthly density of Borrelia-infected nymphs and the monthly density of nymphs. This suggests that, within a certain range of nymphal densities, it may be possible to assess the density of Borrelia-infected I. ricinus nymphs without examining nymphs for B. burgdorferi s.l.
51 citations
TL;DR: A family outbreak of tick-borne encephalitis involving 7 people, all of them hospitalized, was observed in the district of Považská Bystrica (central Slovakia), where the disease was associated with the drinking of unboiled goat milk and ticks recovered from places where goats were grazing.
Abstract: A family outbreak of tick-borne encephalitis involving 7 people, all of them hospitalized, was observed in the district of Povazska Bystrica (central Slovakia). The disease was associated with the drinking of unboiled goat milk and tick-borne encephalitis virus was recovered from Ixodes ricinus ticks collected from places where goats were grazing.
47 citations
TL;DR: Molecular polymorphism of the studied borrelia isolates suggests a complex enzootic potential of B. garinii in northern Europe and implies a novel, seabird tick I. uriae-associated enzootics focus of Lyme disease borReliae in the North Atlantic.
Abstract: Lyme disease Borrelia species are distributed in temperate areas of North America and Eurasia. To elucidate the distribution of borreliae in subarctic regions, strains isolated from Ixodes ricinus and Ixodes uriae ticks found on islands in the northern Atlantic and Baltic Sea were molecularly characterized. All isolates were verified as Borrelia garinii by 16S rRNA gene analysis and immunoblotting with monoclonal antibodies specific for the outer surface proteins A and C. Three ribotypes (RTs) of B. garinii were delineated. I. ricinus complex-associated RT1 was phenotypically most heterogeneous. Two newly identified ribotypes were shared by different tick species and conformed to two established OspA serotypes. RT2 was restricted to the islands in the northern Baltic Sea, whereas RT3 was recovered also from ticks found in the North Atlantic. In conclusion, molecular polymorphism of the studied borrelia isolates suggests a complex enzootic potential of B. garinii in northern Europe and implies a novel, seabird tick I. uriae-associated enzootic focus of Lyme disease borreliae in the North Atlantic.
TL;DR: The CART model discriminates 2 variables that appear to have the greatest effect on the mesoscale occurrence of ticks: altitude and geological substratum, with a drastic decrease of tick frequency above an altitude of approximately 1,100 m and on volcanic substrata.
Abstract: Cases of Lyme disease and tick-borne encephalitis were recognized recently in the Province of Trento, Italian Alps. Assessment of areas of potential risk for these tick-borne diseases is carried out by a model based on classification and regression trees (CART), using both discrete and continuous variables. Data on Ixodes ricinus (L.) occurrence resulted from extensive sampling carried out by standard methods in 99 sites over an area of ≍2,700 km2 in the Province of Trento. A series of environmental parameters were recorded from each site and population densities of roe deer, Capreolus capreolus (L.), were considered. The CART model discriminates 2 variables that appear to have the greatest effect on the mesoscale occurrence of ticks: altitude and geological substratum, with a drastic decrease of tick frequency above an altitude of ≍1,100 m and on volcanic substrata. The model is effective in identifying the mesoscale areas at greater potential risk, with a relatively low sampling effort.
TL;DR: Evidence is provided that tick-borne encephalitis virus and Borrelia burgdorferi s.l. are accumulated in the cement plug in the host skin within the first few hours after tick attachment, and extirpation of the tick without the cementplug did not prevent the transmission by Ixodes ricinus, Ixode persulcatus or Dermacentor reticulatus to mice.
Abstract: We provide evidence that tick-borne encephalitis virus and Borrelia burgdorferi s.l. are accumulated in the cement plug in the host skin within the first few hours after tick attachment. Extirpation of the tick without the cement plug, even very soon after the attachment, did not prevent the transmission by Ixodes ricinus, Ixodes persulcatus or Dermacentor reticulatus to mice. This was within 1 hour in the case of the TBE virus and after 20-22 h of attachment, in the case of Borrelia and I. persulcatus. The epidemiological significance of these findings is discussed.
TL;DR: Of 411 forest birds of 33 species examined near Valtice, Czech Republic, 29% were infested with Ixodes ricinus, and 2.2% were parasitized by Haemaphysalis concinna Koch, which suggested free-living birds may be involved in the circulation of B. burgdorferi sensu lato principally as disseminators of infected ixodid ticks to new area.
Abstract: Of 411 forest birds of 33 species examined near Valtice, Czech Republic, 29% were infested with Ixodes ricinus (L.); 2.2% were parasitized by Haemaphysalis concinna Koch. Borreliae were detected in 5.1 and 11.7% of larval and nymphal I. ricinus , respectively. None of the 13 H. concinna tested was infected. In total, 3.2% of the birds examined were parasitized by I. ricinus immatures infected by borreliae. Borreliae-containing ticks parasitized European robin, Erithacus rubecula (L.); Eurasian blackbird, Turdus merula L.; Blackcap, Sylvia atricapilla (L.); Eurasian chiffchaff, Phylloscopus collyhita (Vieillot); Great tit, Parus major L.; and Eurasian jay, Garrulus glandarius (L.). The isolate BR-34 from a nymphal I. ricinus off a Eurasian blackbird had a sodium dodecyl sulfate-polyacrylamide gel electrophoresis protein pattern, reactions to monoclonal antibodies, and fragments of Hin dIII digested DNA probed with fla and ospA genes that suggested to us that it belongs to the genospecies Borrelia garinii . Free-living birds may be involved in the circulation of B. burgdorferi sensu lato principally as disseminators of infected ixodid ticks to new areas.
TL;DR: Investigation of isolated ecosystems to determine if Lyme borreliosis is maintained in the absence of reservoir-competent small mammals concludes that L. timidus serves as a maintenance host for B. burgdorferi s.l. and its vector, I. ricinus, on both islands.
Abstract: We investigated isolated ecosystems to determine if Lyme borreliosis is maintained in the absence of reservoir-competent small mammals. Human cases of Lyme disease have been reported on the isolated islands of Gotska Sandon and Stora Karlso in the Baltic Sea. The varying hare, Lepus timidus, is the only terrestrial vertebrate species capable of serving as a host for all stages of Ixodes ricinus (L.) on these islands. In August, mean larval infestation on 5 hares from each island was 548 with a maximum of 2,276 larvae on 1 hare. Smaller numbers of nymphal and female ticks were also engorging on the hares. During August-September, B. burgdorferi s.l. was detected in 11-24% of nymphal I. ricinus fed as larvae on hares and in 8-19% of host-seeking nymphal I. ricinus collected from the vegetation. We conclude that L. timidus serves as a maintenance host for B. burgdorferi s.l. and its vector, I. ricinus, on both islands.
TL;DR: The cuticular hydrocarbon composition and a stepwise discriminant analysis are used to elucidate the phenotypic relationships of 66 populations of Ixodes ricinus in Europe and Poland are inseparable from samples collected in Germany, Switzerland and the Italian Alps.
Abstract: 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.
TL;DR: Residents of Europe have been exposed to diverse Lyme disease spirochetes at least since 1884, concurrent with the oldest record of apparent human infection.
Abstract: To determine whether the characteristics of the Lyme disease spirochete (Borrelia burgdorferi) in Europe may have changed during the past century, DNA was amplified from archived Ixodes ricinus ticks. Tick DNA could be amplified, even when ticks had been stored under museum conditions for nearly a century. Spirochetal DNA was detected by polymerase chain reaction in 6 ticks preserved for as long as a century ; the oldest was collected in 1884. Borrelia garinii, which predominates in modern ticks in the region, infected 3 of these older ticks, and the presently infrequent B. burgdorferi sensu stricto infected 2. These data indicate that residents of Europe have been exposed to diverse Lyme disease spirochetes at least since 1884, concurrent with the oldest record of apparent human infection.
TL;DR: The assessment of a widespread distribution of the zoonosis in France which was, until now, exclusively based on an approximate distribution of limited human cases observed in the country is confirmed.
Abstract: Ixodes ricinus is considered as the main vector of Lyme Borreliosis in France. The aim of our investigations was to obtain a comprehensive view of the spatial risk linked to the distribution of the species in our country. Previous studies [1] have provided strong evidence that the species populations are widely distributed, so the objective of the present work was to ascertain the bacteriological infection of the tick by the agent of the zoonosis (Borrelia burgdorferi, sensu lato), over the French territory, whatever the ecological conditions may be. For this purpose, we kept the same framework as that used in our acarological investigation, a phytoecological zoning of the territory into 54 geographically separate and ecologically distinct units distributed into three climatic zones. Batches of ticks, picked up in these different phytoecological units (only two thirds of which were sampled), were submitted for bacteriological investigation. A total of 4,673 ticks were examined, individually, for the presence of Borrelia burgdorferi, by immunofluorescence. Percentages of infection according to the various stages of Ixodes ricinus free stages, collected by flagging, were as follows: 4.95% in 3,247 nymphs, 11.2% in 699 males, 12.5% in 727 females. Larvae were ignored. Practically all the tested units harboured the bacterium. The percentage of tick samples (25 ticks or more) absolutely free of Borrelia, wherever they came from, is very low (not exceeding 10 percent of the sampled forests). Our study confirms the assessment of a widespread distribution of the zoonosis in France which was, until now, exclusively based on an approximate distribution of limited human cases observed in the country.
TL;DR: 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.
Abstract: 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 Gene’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 Gene’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.
TL;DR: The sequential developmental events of Borrelia burgdorferi in histological sections of Ixodes ricinus nymphs before, during and after feeding are reported and the variation in the number of infected ticks was significant, but only during the blood meal.
Abstract: We report the sequential developmental events of Borrelia burgdorferi in histological sections of Ixodes ricinus nymphs before, during and after feeding. During the blood meal a decrease of approximately 50% in the number of infected ticks was recorded (eight out of 76, 11%) in comparison with the infection rate of unfed ticks (12 out of 56, 21%). Spirochetes were detected in tick salivary glands only after 2 days of attachment. From day 3 until drop-off, the number of infected ticks increased to 31% (15 out of 49). A quadratic logistic regression analysis showed that the variation in the number of infected ticks was significant, but only during the blood meal. The drop in the percentage of infected ticks during the first hours following attachment to the host is explained by our observation of spirochetes in the faeces of the ticks. The increase in the infection rate of replete ticks may be due to an uptake of spirochetes from the host skin at the feeding site.
TL;DR: Most animals were infested by only a single tick, but one M. agrestis harboured 43 I. ricinus larvae, and small numbers of Ixodes (Exopalpiger) trianguliceps were also recovered from each farm.
Abstract: Data collected from a longitudinal survey carried out over 2 years on four farms in western France were used to assess the incidence and infestation of Ixodes ricinus on rodents. Once a month, on each farm, 25 Sherman live traps were set in hedges bordering selected pastures. A total of 799 micromammals were examined, including Apodemus sylvaticus, Clethrionomys glareolus, Microtus agrestis, Microtus arvalis, and Crocidura spp. Larvae and nymphs of I. ricinus were found. Small numbers of Ixodes (Exopalpiger) trianguliceps were also recovered from each farm. The mean infestation rate of the I. ricinus larvae (1.6-5.9) among all animals examined varied between farms Most animals were infested by only a single tick, but one M. agrestis harboured 43 I. ricinus larvae. Larvae or nymphs were found throughout the year, with peaks from March to October.
Journal Article•
TL;DR: The engorgement weight was found to be the best criterion for differentiation of male and female nymphs of ixodid ticks.
Abstract: Unfed nymphs of Ixodes ricinus (L.) can be divided into two morphological groups according to the length of idiosoma, scutum, hypostome and palpal segment III, and the number of dorsal alloscutal setae. Specimens of greater body dimensions and more numerous dorsal alloscutal setae moulted predominantly into females. The frequency of different nymphal length categories in field-collected ticks followed a normal distribution. The length of unfed nymphs correlates well with the length (r = 0.7248 +/- 0.0711, P < 0.001) and weight (r = 0.6519 +/- 0.0782, P < 0.001) of engorged nymphs, however, it varies in ticks of different origin. In field-collected ticks, freshly engorged female nymphs were 2.30-2.94 mm long, male nymphs 2.14-2.46 mm long. Feeding period (P < 0.05) and premoulting period (P < 0.001) were significantly longer in female nymphs both in field-collected and laboratory-derived I. ricinus. The engorgement weight was found to be the best criterion for differentiation of male and female nymphs of ixodid ticks. In field-collected nymphs engorged on BALB/c mice, 98.6% of females moulted from nymphs weighting more than 3.60 mg, while in laboratory-derived ticks, 98.4% of females emerged from nymphs of 3.42 mg body mass or more.
01 Jan 1996
TL;DR: Biochemical properties of isolated strain has strongly suggested that these bacteria belong to genus Bartonella (Rochalimaea) and further identification of bacterial DNA with RFLP-PCR has shown characteristics of Bart onella bacilliformis species not recognised in Poland until recently.
Abstract: Ticks Ixodes ricinus have been harvested in park down-town Walcz in June 1994. Presence of Borrelia burgdorferi and rickettsiae has been tested with PCR. B. burgdorferi and Coxiella burnetii have not been detected in any tick whereas characteristic for other rickettsiae DNA fragment of gene encoding citrate-synthase has been found. Bacterial strain has been cultured from the tick. Biochemical properties of isolated strain has strongly suggested that these bacteria belong to genus Bartonella (Rochalimaea). Further identification of bacterial DNA with RFLP-PCR (restriction fragment length polymorphism-PCR) has shown characteristics of Bartonella bacilliformis species not recognised in Poland until recently.
01 Jan 1996
TL;DR: Clinically, babesial infections appeared suddenly with a non periodic high fever, shaking chills, sweat, headache, myalgia and jaundice induced by intravascular hemolysis, and the mortality rate was higher than 50%.
Abstract: The tick transmission of Babesia from infected animals to human has been clearly demonstrated. Including the first case described by Skaraballo in 1957 in Yugoslavia, 22 cases of human babesiosis have been reported in Europe. B. divergens, which is the most common pathogen for cattle, was involved in 17/22 cases. France, British Isles and Ireland accounted for more than half of the cases, occurring especially between May and October, the period of maximal activity of Ixodes ricinus, considered as the major vector. Splenectomy was the main factor of risk which was found in 86% of the patients. Clinically, babesial infections appeared suddenly with a non periodic high fever, shaking chills, sweat, headache, myalgia and jaundice induced by intravascular hemolysis. The mortality rate was higher than 50%. Treatment should be promptly initiated with a massive blood exchange, followed by intravenous clindamycin (600 mg) three time daily. For prophylaxis, attenuated vaccines could provide effective protection in cattle, but no vaccine is available for human protection.
TL;DR: Host preference and biotope usage of H. punctata seems, in general, to prevent this tick from feeding on highly infective Borrelia reservoirs, such as Apodemus mice.
Abstract: The prevalence of infection with Lyme borreliosis spirochetes in nymphal Ixodes ricinus and Haemaphysalis punctata was examined on three Swedish islands in the Baltic Sea. The proportion of H. punctata nymphs infected with Borrelia spirochetes (≈2%) was lower than that of I. ricinus nymphs (11–16%), even on the island of Stora Karlso where both tick species feed on the single mammalian host present, the varying hare, Lepus timidus. Ten of the 12 infected questing H. punctata nymphs harboured very few spirochetes, whereas the remaining two harboured as many as 30–40 spirochetes. However, it remains to be seen whether H. punctata nymphs are capable of transmitting spirochetes during their blood meal and, thus, serving as vectors for Lyme borreliosis spirochetes. On Gotland and Faro, I. ricinus was more abundant than H. punctata in deciduous and coniferous forest, whereas H. punctata was equally or more abundant than I. ricinus in juniper brush areas on open land. Host preference and biotope usage of H. punctata seems, in general, to prevent this tick from feeding on highly infective Borrelia reservoirs, such as Apodemus mice.
TL;DR: Free-living nymphs and adults from Rambouillet and Fontainebleau, 2 major forests of Ile de France, were collected to determine the infection rates of Ixodes ricinus L. by Borrelia burgdorferi.
Abstract: Free-living nymphs and adults from Rambouillet and Fontainebleau, 2 major forests of Ile de France, were collected to determine the infection rates of Ixodes ricinus L. by Borrelia burgdorferi (Johnson, Schmid, Hyde, Steigerwalt & Brenner). Field-collected I. ricinus nymphs and adults were screened for the presence of B. burgdorferi using direct fluorescent antibody assay. The infection rates of nymph, male and female were 12.4% (314), 2.8% (35), and 2.9% (34). No difference in infection rates of nymphs among sites were detected. Spirochetes was isolated from both sites. Isolates from Rambouillet and Fontainebleau were identified as B. burgdorferi sensu stricto and B. garinii, respectively (Baranton, Postic, Saint-Girons, Boerlin, Piffaretti, Assous, and Grimont).
TL;DR: The results confirm that proteins of 22/23 kDa are differentially expressed duringin vitro subcultures and in ticks, and show that proteins which are not detectable afterin vitro culture may be reexpressed after reexposure of B. burgdorferi to its former environment in the tick.
Abstract: A Borrelia garinii isolate (NE11H) was obtained from the hemolymph of infed Ixodes ricinus NE11H expressed four major proteins of 33 kDa, 32 kDa, 23 kDa and 22 kDa During in vitro culture, NE11H successively lost the expression of the 22 kDa and 23 kDa proteins and the NE11H variant (NE11Hp15) was not recognized by an immune serum specific for the OspC protein (anti-OspC IS) However, when reintroduced into tick midguts, NE11Hp15 spirochetes present in the midgut again reacted with anti-OspC IS A clone derived from the wild type line, cNE11H, lacked the 22 kDa but not the 23 kDa protein The 23 kDa protein of cNE11H was recognized by anti-OspC IS In addition, the two descendant lines (NE11Hp15 and cNE11H) lost their capacity to induce clinical arthritis in SCID mice When cNE11H was reintroduced into ticks and reisolated from various tick organs, most reisolates presented the same reaction with anti-OspC IS as cNE11H Interestingly, two reisolates obtained from the tick midgut reexpressed large amounts of the 22 kDa protein which was recognized by anti-OspC IS and these two reisolates induced clinical arthritis in SCID mice The results confirm that proteins of 22/23 kDa are differentially expressed during in vitro subcultures and in ticks, and show that proteins which are not detectable after in vitro culture may be reexpressed after reexposure of B burgdorferi to its former environment in the tick The data suggest that the pathogenicity of B burgdorferi for mice might be influenced by environmental factors via differential expression of 22/23 kDa proteins
01 Jan 1996
TL;DR: Peptide mapping and mab binding studies of virus strains isolated from ticks, man, and mammals over the last 40 years from various parts of Europe revealed a remarkably high degree of homogeneity with respect to their E protein.
Abstract: Tick-borne encephalitis (TBE) virus is one of the most important flavi- viruses causing severe disease in man. Flaviviruses are small enveloped viruses consisting of three proteins termed E (envelope), C (capsid), and M (membrane). The glycoprotein E mediates virus entry and it induces neutralizing antibodies and a protective immunity [1]. Based on agar gel diffusion and antibody adsorption experiments, two different subtypes of TBE virus have been described [2]: a European subtype, which is mainly transmitted by Ixodes ricinus, and a Far Eastern subtype with Ixodes persulcatus as the principal vector. This classification has been confirmed at the molecular level by the use of monoclonal antibodies (mabs) and peptide mapping [3, 4] and, more recently, also by nucleotide sequencing of a European [5] and a Far Eastern virus strain [6]. Peptide mapping and mab binding studies of virus strains isolated from ticks, man, and mammals over the last 40 years from various parts of Europe revealed a remarkably high degree of homogeneity with respect to their E protein [7]. Studies on the molecular epidemiology of TBE virus showed that strains of both the Western and the Far Eastern subtype can be found in the European and Asian regions of the former Soviet Union [8]. In addition, the authors also reported that no statistically significant difference in the degree of protection was detected when mice were immunized with the Austrian vaccine (strain Neudorfl) and challenged with Asian isolates of TBE virus. Clinical Features
Journal Article•
TL;DR: Data collected from a longitudinal survey carried out over a 2 year period in four herds located in western France were used to assess the infestation level in cattle by female ixodes ricinus and to describe its seasonality.
Abstract: Data collected from a longitudinal survey carried out over a 2 year period in four herds located in western France were used to assess the infestation level in cattle by female ixodes ricinus and to describe its seasonality. Farms were visited once a month. The population studied consisted of calves, heifers and dairy cows (of Holstein and Norman de breeds). The total number of animals monitored varied from 207 to 173 throughout the study, because of the culling of dairy cows and birth of calves. The infestation level by l ricinus varied from one herd to another. Heifers were found to have a greater level of infestation than dairy cows and calves. The infestation rate appeared to be low, ie, most animals (between 47 and 83%) were infested by only one tick in the axilla. The seasonal distribution of ticks showed two peaks, one in spring and a second lower one in autumn, with slight fluctuations between herds and years. The number of ticks on cattle and the percentage of infested animals showed a parallel seasonality.
TL;DR: It was found that annual incidence of human Lyme borreliosis in the region correlated better with the proportion of heavily infected ticks than with the overall infection rate of the ticks.
Abstract: The proposed method consists in examining individual host-seeking vector ticks of the Ixodes ricinus complex by microscopy for borreliae and evaluating the proportion of ticks with more than 100 borreliae The investigations were carried out in a deciduous oak forest habitat in South Moravia, Czech Republic, over four years (1991-1994) In May (ie, at the peak of seasonal activity of I ricinus), about 150 nymphal and 200 adult ticks were examined each year It was found that annual incidence of human Lyme borreliosis in the region correlated better with the proportion of heavily infected ticks than with the overall infection rate of the ticks