Showing papers on "Ixodes ricinus published in 1999"
TL;DR: It is concluded that the relatively mild climate of the 1990s in Sweden is probably one of the primary reasons for the observed increase of density and geographic range of I. ricinus ticks.
Abstract: We examined whether a reported northward expansion of the geographic distribution limit of the disease-transmitting tick Ixodes ricinus and an increased tick density between the early 1980s and mid...
515 citations
TL;DR: The application of the assay to DNA extracts from 121 Ixodes ricinus ticks collected from roe deer demonstrated that 45% of these ticks carried EhrlichiaDNA, and more than half of these positive ticks carried species with 16S rRNA gene sequences closely related to those of E. phagocytophila and the human granulocytic ehrlichiosis agent.
Abstract: A sensitive and specific PCR hybridization assay was developed for the simultaneous detection and identification of Ehrlichia and Borrelia burgdorferi sensu lato. In separate assays the 16S rRNA gene of Ehrlichia species and the 23S-5S rRNA spacer region of B. burgdorferi sensu lato were amplified and labeled by PCR. These PCR products were used in a reverse line blot hybridization assay in which oligonucleotide probes are covalently linked to a membrane in parallel lines. Hybridization of the samples with the oligonucleotide probes on this membrane enabled the simultaneous detection and identification of Ehrlichia, B. burgdorferi, and Bartonella species in 40 different samples. The application of the assay to DNA extracts from 121 Ixodes ricinus ticks collected from roe deer demonstrated that 45% of these ticks carried Ehrlichia DNA. More than half of these positive ticks carried species with 16S rRNA gene sequences closely related to those of E. phagocytophila and the human granulocytic ehrlichiosis agent. The majority of the other positive ticks were infected with a newly identified Ehrlichia-like species. In addition, 13% of the ticks were infected with one or more B. burgdorferi genospecies. In more than 70% of the ticks 16S rRNA gene sequences for Bartonella species or other species closely related to Bartonella were found. In five of the ticks both Ehrlichia and B. burgdorferi species were detected.
443 citations
TL;DR: The ratio of larvae to nymphs feeding on rodents thus increases with increasing humidity, contributing to the seasonal and geographical variation in disease transmission dynamics.
Abstract: Rodents play a significant role in enzootic cycles of tick-borne pathogens, notably, in the northern hemisphere, tick-borne encephalitis virus and Lyme borreliosis spirochaetes. The relative numbers of nymphal and larval ticks feeding on rodents are crucial variables in determining the probability of rodent infection and the degree of amplification of infection prevalence in the tick population. Manipulation of the microclimate within quasinatural experimental arenas revealed that under increasingly dry conditions the numbers of unfed nymphal Ixodes ricinus L. questing in upper layers of the herbage decreased, whereas the rate of fat use and the numbers of nymphs feeding on small rodents, both increased. This is consistent with nymphs descending to the moist lower vegetation layers for water replenishment, where they would come into contact with small hosts. Very few larvae quested or fed on rodents under the dry conditions, but many more did so once the humidity increased, suggesting that larvae escape desiccation by becoming quiescent. The ratio of larvae to nymphs feeding on rodents thus increases with increasing humidity, contributing to the seasonal and geographical variation in disease transmission dynamics.
334 citations
TL;DR: The risk for travelers of acquiring TBE is increasing with the recent rise in tourism to areas of endemicity during spring and summer, particularly in rural areas favored by the vector.
Abstract: Tick-borne encephalitis (TBE) is a zoonotic arbovirus infection endemic to Russia and Eastern and Central Europe. Despite being a common and serious life-threatening disease for which a mass vaccination program was implemented in Austria, there is only limited reference to this disease in the English-language literature. TBE is transmitted to humans usually by the bite of a tick (either Ixodes persulcatus or Ixodes ricinus); occasionally, cases occur following consumption of infected unpasteurized milk. Transmission is seasonal and occurs in spring and summer, particularly in rural areas favored by the vector. TBE is a serious cause of acute central nervous system disease, which may result in death or long-term neurological sequelae. Effective vaccines are available in a few countries. The risk for travelers of acquiring TBE is increasing with the recent rise in tourism to areas of endemicity during spring and summer.
304 citations
TL;DR: This work identifies the particular climatic factors that permit such patterns of tick seasonal dynamics as the primary predictors for the focal distribution of TBE.
Abstract: Tick-borne encephalitis (TBE) virus has a highly focal distribution through Eurasia. Endemic cycles appear to depend on the transmission of non-systemic infections between ticks co-feeding on the same rodent hosts. The particular features of seasonal dynamics and infestation patterns of larval and nymphal Ixodes ricinus, but not Dermacentor reticulatus, from 4 regions within TBE foci in Slovakia, are such as to promote TBE virus transmission. The distributions of larvae and nymphs on their principal rodent hosts are highly aggregated and, rather than being independent, the distributions of each stage are coincident so that the same ca. 20% of hosts feed about three-quarters of both larvae and nymphs. This results in twice the number of infectible larvae feeding alongside potentially infected nymphs compared with the null hypothesis of independent distributions. Overall, co-feeding transmission under these circumstances brings the reproductive number (R0) for TBE virus to a level that accounts quantitatively for maintained endemic cycles. Essential for coincident aggregated distributions of larvae and nymphs is their synchronous seasonal activity. Preliminary comparisons support the prediction of a greater degree of coincident seasonality within recorded TBE foci than outside. This identifies the particular climatic factors that permit such patterns of tick seasonal dynamics as the primary predictors for the focal distribution of TBE.
300 citations
TL;DR: Each rodent species showed different host infection, different host infectivity and contributed differently to the moulting success of feeding ticks, which influence differentially the pattern of transmission of B. afzelii from Clethrionomys voles and Apodemus mice to I. ricinus ticks.
Abstract: This study deals with the ecology of Lyme borreliosis in Europe. The relationships between Borrelia burgdorferi sensu lato spirochetes, Clethrionomys and Apodemus rodent reservoirs and the Ixodes ricinus tick vector were investigated during 16 consecutive months in an enzootic area in Switzerland. Cultivation of ear skin biopsies was used to isolate spirochetes from C. glareolus, A. sylvaticus, A. flavicollis and Glis glis. Borrelia infection was more frequently observed in Clethrionomys than in Apodemus. Tick xenodiagnosis was used to determine the infectivity of rodents. The infection rate in ticks fed on Clethrionomys was higher than that in ticks fed on Apodemus, but Apodemus yielded more infected ticks than Clethrionomys because of a better tick moulting success. Xenodiagnostic ticks were placed into BSK medium to obtain isolates. Isolates from rodents and rodent-feeding ticks were all identified as B. afzelii. The follow-up of the infectivity status of repeatedly recaptured rodents clearly demonstrated that these hosts remained infective for ticks during winter till the following spring. Comparing C. glareolus and A. sylvaticus, each rodent species showed different host infection, different host infectivity and contributed differently to the moulting success of feeding ticks. These factors influence differentially the pattern of transmission of B. afzelii from Clethrionomys voles and Apodemus mice to I. ricinus ticks.
189 citations
TL;DR: It is concluded that Lyme borreliosis can be contracted even in urban environments not populated with large mammals like deer or elk, and the use of measures to improve the awareness of the general population and health care officials of the risk of contracting the disease is warranted.
Abstract: Lyme borreliosis, an infection caused by the tick-borne spirochete Borrelia burgdorferi, is a major health problem for populations in areas of endemicity in the Northern Hemisphere In the present study we assessed the density of ticks and the prevalence of B burgdorferi sensu lato among ticks in popular urban recreational areas of Helsinki, Finland Altogether 1,688 Ixodes ricinus ticks were collected from five areas located within 5 km of the downtown section of Helsinki, and 726 of them (303 nymphs, 189 females, and 234 males) were randomly chosen for laboratory analysis The midguts of the ticks were divided into three pieces, one for dark-field microscopy, one for cultivation in BSK-II medium, and one for PCR analysis Ticks were found in all the study areas; their densities varied from 1 to 36 per 100 m along which a cloth was dragged The rate of tick infection with B burgdorferi sensu lato varied from 19 to 55%, with the average being 32% Borellia afzelii was the most predominant genospecies in all the areas, and no B burgdorferi sensu stricto isolates were detected Only two ticks were concurrently infected with both B afzelii and Borrelia garinii Dark-field microscopy gave more positive results for B burgdorferi than did cultivation or PCR analysis However, the agreement between all three methods was fairly good We conclude that Lyme borreliosis can be contracted even in urban environments not populated with large mammals like deer or elk The disease should be taken into account in the differential diagnosis of certain symptoms of patients from these areas, and the use of measures to improve the awareness of the general population and health care officials of the risk of contracting the disease is warranted
128 citations
TL;DR: Rickettsia isolated from Ixodes ricinus ticks in Sweden showed that it has 100% homology with the deposited sequence of the citrate synthase gene of Rickettsia helvetica, which conforms to those of other studies of spotted fever group rickettsiae in hard ticks in Europe.
Abstract: In the present study further characterization of the amplified sequence of the citrate synthase gene of the spotted fever group Rickettsia isolated from Ixodes ricinus ticks in Sweden showed that it has 100% homology with the deposited sequence of the citrate synthase gene of Rickettsia helvetica. The restriction fragment length polymorphism (RFLP) pattern of an amplified 382-bp product of the citrate synthase sequence, defined by primers RpCS877 and RpCS1258, yielded fragments for our isolate that could be visualized as a double band that migrated at approximately 44 bp, another double band at 85 bp, and a single band at nearly 120 bp after digestion with the restriction enzyme AluI. When calculating a theoretical PCR-RFLP pattern of the sequence of the citrate synthase gene of R. helvetica from the known positions where the AluI enzyme cuts, we arrived at the same pattern that was obtained for our isolate, a pattern distinctly different from the previously published PCR-RFLP pattern for R. helvetica. Investigation of 125 living I. ricinus ticks showed a higher prevalence of rickettsial DNA in these ticks than we had found in an earlier study. Rickettsial DNA was detected by amplification of the 16S rRNA gene, for which a seminested primer system consisting of two oligonucleotide primer pairs was used. Of the 125 ticks, some were pooled, giving a total of 82 tick samples, of which 20 were found to be positive for the rickettsial DNA gene investigated. When considering the fact that some of the positive samples were pooled, the minimum possible prevalence in these ticks was 20 of 125 (16%) and the maximum possible prevalence was 46 of 125 (36.8%). These prevalence estimates conform to those of other studies of spotted fever group rickettsiae in hard ticks in Europe.
111 citations
01 Dec 1999-Zentralblatt Fur Bakteriologie-international Journal of Medical Microbiology Virology Parasitology and Infectious Diseases
TL;DR: Only in certain places do larval and nymphal ticks feed together on the same hosts with sufficient coincidence to ensure TBE virus survival, and these environmental factors are being identified with the help of remotely-sensed meteorological satellite imagery to create predictive risk maps of TBE foci.
Abstract: Although TBE virus can be transmitted in the laboratory by a wide variety of ixodid tick species to a wide variety of vertebrate host species, nevertheless in nature endemic cycles of TBE virus depend principally on just two tick species, Ixodes ricinus in the western and I. persulcatus in the eastern Palaearctic. A complete transmission cycle, from tick to tick via vertebrates, occurs most efficiently between co-feeding ticks in the absence of a systemic viraemia. This non-systemic route depends on TBE virus replication within particular immunocompetent cells in the skin, and only certain vertebrate species, notably Apodemus mice, are susceptible to this. Amongst the potential tick vectors in Europe, only I. ricinus has the correct host relationships and appropriate natural life cycle to support such non-systemic transmission cycles. Within the wide European distribution of this tick-host relationship, only in certain places do larval and nymphal ticks feed together on the same hosts with sufficient coincidence to ensure TBE virus survival. The environmental factors that determine this seasonal coincidence are being identified with the help of remotely-sensed meteorological satellite imagery to create predictive risk maps of TBE foci.
109 citations
TL;DR: A total of 287 adult Ixodes ricinus ticks, collected in two regions of southern Germany where Borrelia burgdorferi infections are known to be endemic, were examined for the presence of 16S ribosomal DNA specific for the Ehrlichia phagocytophila genogroup.
Abstract: A total of 287 adult Ixodes ricinus ticks, collected in two regions of southern Germany (Frankonia and Baden-Wurttemberg) where Borrelia burgdorferi infections are known to be endemic, were examined for the presence of 16S ribosomal DNA specific for the Ehrlichia phagocytophila genogroup, E. chaffeensis, E. canis, and B. burgdorferi by nested PCR. Totals of 2.2% (6 of 275) and 21.8% (65 of 275) of the ticks were positive for the E. phagocytophila genogroup and B. burgdorferi, respectively. Two ticks (0.7%) were coinfected with both bacteria. Of 12 engorged I. ricinus ticks collected from two deer, 8 (67%) were positive for the E. phagocytophila genogroup and one (8%) was positive for B. burgdorferi. There was no evidence of infection with E. canis or E. chaffeensis in the investigated tick population. The nucleotide sequences of the 546-bp Ehrlichia PCR products differed at one or two positions from the original sequence of the human granulocytic ehrlichiosis (HGE) agent (S.-M. Chen, J. S. Dumler, J. S. Bakken, and D. H. Walker, J. Clin. Microbiol. 32:589-595, 1994). Three groups of sequence variants were detected; two of these were known to occur in other areas in Europe or the United States, whereas one has not been reported before. Thus, in the German I. ricinus tick population closely related granulocytic ehrlichiae are prevalent, which might represent variants of E. phagocytophila or the HGE agent.
103 citations
TL;DR: Ixodes ricinus ticks infected with Borrelia burgdorferi sensu lato were numerous on the edges of paths and roads in a recreational park in south-western Ireland, but a negative relationship was shown between tick abundance and tick infection rates.
Abstract: Ixodes ricinus ticks infected with Borrelia burgdorferi sensu lato were numerous on the edges of paths and roads in a recreational park in south-western Ireland. The abundance of ticks at different sites was related to the presence of deer, but a negative relationship was shown between tick abundance and tick infection rates. This is thought to be due to the deposition of large numbers of uninfected ticks by deer, which are apparently not good reservoir hosts of B. burgdorferi s.l. Blood meal analysis only detected deer DNA in uninfected nymphs. Reservoir competent rodents, Apodemus sylvaticus and Clethrionomys glareolus, were abundant at all sites and a high proportion of captured specimens were infested with larval ticks. However, very few rodents were infected with B. burgdorferi s.l. and none of the unfed infected nymphs analysed for the identity of their larval blood meal had fed on rodents. The spirochaetes detected in I. ricinus in the study area may be poorly adapted to rodents or are not transmitted readily because of the absence of nymphal infestation. The majority of spirochaetes in these ticks were apparently acquired from non-rodent hosts, such as birds.
Journal Article•
TL;DR: A synthesis on tick distribution, their biology and their role as vectors of pathogens in domestic animals, particularly cattle, in Tunisia is reported.
Abstract: Ticks (Ixodidae) play a significant role as vectors of pathogens of domestic animals in Tunisia. The major losses caused by ticks are related to transmission of protozoan parasites. These include agents of tropical theileriosis and babesiosis in ruminants. Since 1991, we conducted research studies on tick population of livestock in Tunisia. This overview reports a synthesis on tick distribution, their biology and their role as vectors of pathogens in domestic animals, particularly cattle. During the whole period of the study about 15,000 tick specimens were collected from different zones of the country. A total of 14 species were identified. Hyalomma detritum detritum was the most abundant and important (vector of Theileria annulata) species infesting cattle. Hyalomma dromedarii and Hyalomma impeltatum were collected on domestic ruminants in the arid and desertic zones. Hyalomma marginatum marginatum and Hyalomma anatolicum excavatum were widespread and found on livestock hosts. Ixodes ricinus, vector of Babesia divergens and Borrelia burgdorferi sl, colonises mainly the humid zone. Boophilus annulatus and Rhipicephalus bursa infesting cattle, sheep and goats were found in the sub-humid and semi-arid zones. Haemaphysalis sulcata and Hae. punctata were collected in humid and sub-humid zones on cattle and sheep. Rhipicephalus turanicus were collected in different regions, on different animal species. Rhipicephalus sanguineus, tick of dogs, were often collected on livestock. Only few specimens of Hyalomma marginatum rufipes and Hyalomma franchinii were collected.
TL;DR: Adult Ixodes ricinus (Acari: Ixodidae) ticks collected near Ljubljana, Slovenia, were tested for the agent of human granulocytic ehrlichiosis (HGE) by using PCR assays based on the 16S rRNA gene, providing additional evidence that the ticks were infected with the HGE agent.
Abstract: Adult Ixodes ricinus (Acari: Ixodidae) ticks collected near Ljubljana, Slovenia, were tested for the agent of human granulocytic ehrlichiosis (HGE) by using PCR assays based on the 16S rRNA gene. Three (3.2%) of 93 ticks were found to contain granulocytic ehrlichiae. Nucleotide sequences of portions of the bacterial groESL heat shock operon amplified from these ticks were identical or nearly (99.8%) identical to those previously determined for human patients with HGE from Slovenia, providing additional evidence that the ticks were infected with the HGE agent. This study identified I. ricinus as the likely vector for these ehrlichial pathogens of humans in this part of Europe.
TL;DR: Results show that GE that are closely related to the HGE agent are present in Southern Germany, and that coinfection with B. burgdorferi is common in GE-infected ticks.
Abstract: Human granulocytic ehrlichiosis (HGE) is an emerging infectious disease recognized in the Western hemisphere. HGE is well known to occur in North America, but records from outside the United States are sparse. The great majority of data from Europe are restricted to seroprevalence studies and molecular biological detection of granulocytic ehrlichiae (GE) in ticks and mammals, but include defined cases from Slovenia. They argue for the existence of this disease in many parts of Europe. In the present study, 510 Ixodes ricinus ticks collected in five different regions of Southern Germany were investigated for the presence of GE and Borrelia burgdorferi sensu lato using polymerase chain reaction. In all, 8 (1.6%) of the 492 ticks that could be evaluated (193 females, 208 males, and 91 nymphs) contained GE and 178 (36.2%) B. burgdorferi s.l.. Four of these ticks were infected with both pathogens. Interestingly, all ehrlichia-infected ticks were adults and all were collected in the English Garden, a recreational park area located in the city of Munich. Sequencing of the 16S rDNA (bp 1–1101) of four of the GE showed 100% sequence identity to each other and greater than 99.9% identity with the published sequence of the HGE agent. The four GE differed in respect to other hitherto described GE by a nucleotide exchange at position 336. These results show that GE that are closely related to the HGE agent are present in Southern Germany, and that coinfection with B. burgdorferi is common in GE-infected ticks. However, in contrast to B. burgdorferi which is endemic everywhere in Southern Germany, the distribution of GE seems to be focal.
TL;DR: Adult Ixodes ricinus ticks were collected in Switzerland and tested for the presence of coinfection with Borrelia burgdorferi sensu lato and the human granulocytic ehrlichiosis (HGE) agent by real-time PCR.
Abstract: Adult Ixodes ricinus ticks were collected in Switzerland and tested for the presence of coinfection with Borrelia burgdorferi sensu lato and the human granulocytic ehrlichiosis (HGE) agent by real-time PCR. Of 100 ticks, 49% were positive for B. burgdorferi and 2% were positive for the HGE agent. The two HGE agent-positive ticks were also found to be positive for B. burgdorferi.
TL;DR: It is suggested that tick saliva can upregulate the IL‐10 production at the tick feeding site, which consecutively inhibits the elaboration of pro‐inflammatory cytokines, for example IFN‐γ.
Abstract: Tick saliva has been shown to modulate host immunity by a so far unknown mechanism. We have demonstrated an inverted effect of salivary gland extract (SGE), derived from partially fed Ixodes ricinus females, on the production of two cytokines, interferon (IFN)-γ and interleukin (IL)-10, in vitro. While SGE markedly suppressed the elaboration of IFN-γ by mouse splenocytes stimulated with lipopolysaccharide (LPS), the production of IL-10 was increased in comparison with SGE-untreated cultures. The suppressive effect of SGE could be abolished by the addition of an IL-10 neutralizing monoclonal antibody to splenocyte cultures. Similar results were obtained when live Borrelia afzelii spirochetes, which are transmitted in Europe by I. ricinus ticks, were used for the cytokine induction. These results suggest that tick saliva can upregulate the IL-10 production at the tick feeding site, which consecutively inhibits the elaboration of pro-inflammatory cytokines, for example IFN-γ. This immunosuppression may facilitate the establishment of tick-transmitted pathogens in the host.
TL;DR: The infection prevalence observed in this area is among the highest observed in Europe, and isolation success was higher when the infection degree in ticks was high.
Abstract: In Europe, Borrelia burgdorferi sensu lato is diverse, including B.burgdorferi s.s., B.garinii, B.afzelii, B.valaisiana and B.lusitaniae. In this study, we focused on the distribution of the different B.burgdorferi species among Ixodes ricinus adult ticks collected in an endemic area within Slovakia. We compared results of prevalence of B.burgdorferi infection in ticks obtained by immunofluorescence (IF) and by isolation. Isolates were characterized by restriction fragment length polymorphism (RFLP) of the rrf-rrl intergenic spacer genes using MseI. Using immunofluorescence we observed that 56/114 (49%) ticks were infected by B.burgdorferi s.l. Males were found to be more often infected (32/57, 56%) than females (24/57, 42%) but the difference was not significant (p = 0.1895). From the same 114 ticks a total of 37 isolates were obtained: 19 from males (33%) and 18 from females (32%). The RFLP identification revealed 25 B.afzelii (68%), 5 B.garinii (14%), 5 B.valaisiana (14%) and 2 B.lusitaniae (5%). The infection in ticks was more often detected by IF than by isolation (p = 0.0153) and isolation success was higher when the infection degree in ticks was high (p = 0.0397). The infection prevalence observed in this area is among the highest observed in Europe.
TL;DR: Using in vitro assays, salivary gland extracts of the ixodid ticks, Ixodes ricinus, I. hexagonus, and I. uriae, were shown to inhibit activity of the alternative pathway of complement.
01 Dec 1999-Zentralblatt Fur Bakteriologie-international Journal of Medical Microbiology Virology Parasitology and Infectious Diseases
TL;DR: The principal scheme of TBE virus circulation related to the development of three successive generations of the main vector is presented and the main parameter of epizootic activity and epidemic manifestation of natural foci and their long-term fluctuations in different regions are discussed.
Abstract: Summary Tick-borne encephalitis (TBE) is a classic obligatorily transmissible viral infection with natural focality, which is widespread mainly in Eurasian forests of the temperate zone. Virus was discovered in the Russian Far East in 1937. Its main long-term reservoirs and vectors in natural foci are Ixodes persulcatus and I. ricinus ticks. Boundaries of the virus range and the location of natural foci within it are closely associated with the distribution pattern of these ticks. The largest categories of TBE range zoning are described. Each natural focus functions as a relatively autonomous parasitic system. The principal scheme of TBE virus circulation related to the development of three successive generations of the main vector is presented. The main parameter of epizootic activity and epidemic manifestation of natural foci and their long-term fluctuations in different regions are discussed. TBE morbidity in Russia and its dynamics during approximately 45 years are analysed.
TL;DR: The occurrence of this agent in I. ricinus in Switzerland presents a potential danger of transmission of granulocytic ehrlichiosis to dogs, horses, and humans.
Abstract: A total of 1,667 Ixodes ricinus ticks were collected from five regions in Switzerland where there have been sporadic occurrences of granulocytic ehrlichiosis in dogs and horses. The ticks were examined for rickettsiae of the Ehrlichia phagocytophila group via nested PCR. Twenty-one ticks (1.3%) were positive; 3 (0.5%) were nymphs, 6 (1.3%) were adult males, and 12 (1.9%) were adult females. The number of positive ticks varied with the stage of development and with the geographical origin. Nucleotide sequencing of the isolated PCR products identified these products as part of the 16S rRNA gene of Ehrlichia. In addition, these products had 100% homology with the agent of human granulocytic ehrlichiosis. The occurrence of this agent in I. ricinus in Switzerland presents a potential danger of transmission of granulocytic ehrlichiosis to dogs, horses, and humans.
01 Dec 1999-Zentralblatt Fur Bakteriologie-international Journal of Medical Microbiology Virology Parasitology and Infectious Diseases
TL;DR: The first isolation of B. burgdorferi sensu lato from material of Slovene patients succeeded in 1988 while the first isolates from ticks were obtained as late as 1993 as discussed by the authors.
Abstract: Summary Basic epidemiological findings on Lyme borreliosis in Slovenia are presented. Data on vertebrate reservoir hosts are relatively modest. The presence of Borrelia burgdorferi sensu lato was demonstrated in about 20% of deer and 15–41% of examined small mammals. The presence of B. burgdorferi sensu lato was found by polymerase chain reaction in one half of 34 examined small mammals. Ixodes ricinus ticks have been found infected in all geographical regions of Slovenia examined till now. The highest infection rate was detected in the central part of Slovenia where almost 50% of adult ticks and one third of nymphs were positive by culture. The first isolation of B. burgdorferi sensu lato from material of Slovene patients succeeded in 1988 while the first isolates from ticks were obtained as late as 1993. The source material of human isolates has been skin, blood, cerebrospinal fluid, as well as synovial tissue and fluid. Thus far four Borrelia species were found by isolation to cause disease in humans: B. afzelii, B. garinii, B. burgdorferi sensu stricto, and B. bissettii. The majority of typed isolates belong to B. afzelii, but B. garinii slightly predominates among strains cultured from cerebrospinal fluid. Lyme borreliosis has been mandatory reportable in Slovenia for the last 11 years. It is the most common tick-borne disease and is present all over the country. The incidence has been increasing. In 1997 155/100 000 cases were recorded; in some regions the incidence was even substantially higher. The disease affects both sexes (as a rule more often women than men) and all age groups. The incidence is the highest in persons 30–50 years of age, followed by children aged 6–15 years. Erythema migrans is by far the most common recorded manifestation.
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TL;DR: The obtained results confirmed that B. burgdorferi s.l. is present throughout the distributional areas of I. ricinus in Poland and that a prevalence of spirochete-infected ticks may be high in some locations.
Abstract: In 1996-1998, a total of 2285 Ixodes ricinus ticks (1063 nymphs, 637 males, 585 females) were collected from vegetation from 25 different localities in the 8 Polish provinces throughout the country. Ticks inhabited all 25 collection sites. The average number of ticks per collection site was 91.4 +/- 13.7. All 2285 ticks were examined for Borrelia burgdorferi sensu lato (s.l.) presence, of which 1333 specimens from 3 provinces were tested by routine indirect immunofluorescence assay (IFA) using polyclonal antibody PAB 1B29. The remaining 952 specimens from 5 provinces were examined by polymerase chain reaction (PCR), using FL6 and FL7 primers. The overall infection rate in ticks estimated by these 2 methods was 10. 2%. Nymphs showed lower positivity rate (6.2%) as compared to adult ticks (14.9% in females and 12.4% in males). The highest percentage of infected I. ricinus ticks (37.5%) was noted in the Katowice province while the lowest (4.1%) in the Bia ystok province. In particular collection sites, infection rates varied from 0-37.5%. The obtained results confirmed that B. burgdorferi s.l. is present throughout the distributional areas of I. ricinus in Poland and that a prevalence of spirochete-infected ticks may be high in some locations.
TL;DR: The Rambouillet Forest, a Lyme disease-endemic area near Paris, France, was surveyed from September 1994 to October 1995 to determine the risk periods and zones for humans, and significant variation in nymphal abundance between zones according to the density of cervids was observed.
Abstract: The Rambouillet Forest, a Lyme disease-endemic area near Paris, France, was surveyed from September 1994 to October 1995 to determine the risk periods and zones for humans. Firstly, during the period of Ixodes ricinus activity, abundance of nymphs is greater in spring than in autumn. Secondly, we observed significant variation in nymphal abundance between zones according to the density of cervids. The polymerase chain reaction (PCR) was used to detect DNA of Borrelia burgdorferi sensu lato in 461 unfed nymphs. DNA was detected in 38 nymphs (8.2%). By genospecific PCR based on the OspA gene, we detected the three pathogenic spirochetes with occurrences of 10.3, 31.1 and 58.6 for B. burgdorferi s.s., Borrelia garinii and Borrelia afzelii, respectively, indicating that B. afzelii is probably the main Borrelia species in the Rambouillet Forest. Finally, 11.5% of positive nymphs exhibited a double infection. Infection rates of I. ricinus nymphs by B. burgdorferi s.l. were not significantly different throughout the year for a given area, indicating that the risk periods of acquiring Lyme disease are mainly linked to nymph activity and correspond to spring and autumn. Likewise infection rates of nymphs were not significantly different between zones with a high density of deer (more than 100 animals per 100 ha) and zones with lower deer density (less than 20 animals per 100 ha). In addition to the role of deer as an amplifier of tick populations, these data indicate that zones with a high density of cervids should be considered as higher risk areas. © Rapid Science Ltd. 1998
TL;DR: Geostatistics (cokriging) were used to model the cross-correlated information between satellite-derived vegetation and climate variables and actual records of the tick Ixodes ricinus in the western Palearctic, and the output was used to map the habitat suitability for I. ricinus on a continental scale.
Abstract: Geostatistics (cokriging) were used to model the cross-correlated information between satellite-derived vegetation and climate variables and actual records of the tick Ixodes ricinus in the western Palearctic. The output was used to map the habitat suitability for I. ricinus on a continental scale. A database of collecting localities of I. ricinus was built up from a total of 812 records. This database has been cross-tabulated with satellite NOAA AVHRR pictures obtained from 1982 to 1994 over the Palearctic at 10 day intervals, with a resolution of 8 km per pixel. A cokriging system was generated to exploit satellite-derived data and to estimate the distribution of I. ricinus. Three vegetation (standard NDVI values) and four temperature variables output the habitat suitability prediction with a sensitivity of 0.98 and a specificity of 0.92. Results obtained with the model closely agreed with actual records of the tick, with 4 and 3% of false-positive and false-negative sites, respectively. Such statistical analysis can guide field work towards the correct interpretation of the distributional limits of ticks and may also be used to make predictions about the impact of global change on tick distributional ranges.
Journal Article•
TL;DR: Although ticks were recovered from people throughout the year, the highest frequencies of I. ricinus bites were in May, June and July, while R. sanguineus was found to be associated with the dog.
Abstract: In 1995 and 1996, 318 ticks were recovered from 240 people in Liguria (Province of Savona, Italy). Most of the ticks (284; 89.3%) were sheep ticks, Ixodes ricinus. Rhipicephalus sanguineus (31; 9.8%) and Dermacentor marginatus (3; 0.9%) were also recorded. All three life stages of I. ricinus were found on humans while only nymphs and adults of R. sanguineus and adults of D. marginatus were collected. Human tickbites were most frequent in the municipalities of the Province where roe deer density was highest. The number of tickbites in this area was about 500 per 100,000 residents over the period of observation. Most cases of tickbite were observed in children (11.2%), students (25.6%), workers (22.4%) and retired people (24%). Although ticks were recovered from people throughout the year, the highest frequencies of I. ricinus bites were in May, June and July. In the study area natural hosts were also studied. Six tick species were identified (I. ricinus, I. hexagonus, D. marginatus, R. bursa, R. sanguineus, R. turanicus). I. ricinus and R. sanguineus were the most abundant species. I. ricinus was recorded more frequently from ruminants particularly roe deer, while R. sanguineus was found to be associated with the dog.
TL;DR: Results show for the first time that HGE is probably common in southeastern Europe and provides evidence of coinfection or concurrent infection of patients with Lyme disease and HGE, thus supporting the possible role of I. ricinus for transmitting the HGE agent.
Abstract: Human granulocytic ehrlichiosis (HGE) is a recently described rickettsiosis in the United States transmitted by Ixodes species ticks. In Europe, only a few studies on HGE exist. Two hundred Bulgarian patients with tick bites and 70 healthy blood donors were tested for HGE using an immunofluorescence assay with the HGE agent as an antigen. Elevated antibody titers (> or = 1:80) were found in 14 (9.7 %) of 145 patients with erythema migrans, two (8%) of 25 tick-exposed patients with lymphadenopathy only, one (20%) of five patients with tick bite with fever, chills, and headache, one (4%) of 25 healthy tick-exposed patients, and two (2.9%) of 70 blood donors. These results show for the first time that HGE is probably common in southeastern Europe. The study provides evidence of coinfection or concurrent infection of patients with Lyme disease and HGE, thus supporting the possible role of I. ricinus for transmitting the HGE agent.
TL;DR: Free-living adult Ixodes ricinus L, were collected in Amdoun, situated in the Kroumiry mountains in northwestern Tunisia (North Africa), and spirochetes that had been isolated from I. ricinus from Ain Drahim in 1988 were identified as Borrelia lusitaniae (formerly genospecies PotiB2).
Abstract: Free-living adult Ixodes ricinus L, were collected in Amdoun, situated in the Kroumiry mountains in northwestern Tunisia (North Africa). Using direct fluorescence antibody assay, the infection rate of field-collected I. ricinus by Borrelia burgdorferi sensu lato was 30.5% (n = 72). No difference in infection rate was observed between male and female ticks. Spirochetes that had been isolated from I. ricinus from Ain Drahim (Kroumiry Mountains) in 1988 were identified as Borrelia lusitaniae (formerly genospecies PotiB2). This is the first identification of a genospecies of Borrelia burgdorferi sensu lato from the continent of Africa.
01 Dec 1999-Zentralblatt Fur Bakteriologie-international Journal of Medical Microbiology Virology Parasitology and Infectious Diseases
TL;DR: TBEV prevalence data indicate that residents and visitors of areas in Germany known for high endemic activity take a significant risk of contracting TBEV infection, if bitten by ticks.
Abstract: The prevalence of tick-borne encephalitis virus (TBEV) in Ixodes ricinus tick populations in endemic areas of Germany with the highest TBE risk is unknown. Annual and seasonal differences in TBEV prevalence have also not been studied. Against this background, in May 1997 we started a systematic virus surveillance programme in ticks collected in locations known to have a high incidence of autochthonous TBE cases. These were 5 locations in Baden-Wurttemberg (Black Forest) and 8 locations in Bavaria (surrounding Passau). Field-collected ticks were randomly assigned to pools of 10 adults or 20 nymphs, respectively. The tick pools were tested for the presence of TBEV-RNA using a newly developed, sensitive nested reverse transcriptase polymerase chain reaction assay (nRT-PCR). The primer pairs were selected from the 5'-terminal noncoding region, a highly conserved part of the virus. The specificity was tested by computer homology searches of sequences, as well as by sequencing of the first and the second amplificates, by Southern blot hybridisation with a DIG-labelled oligonucleotide probe, and by restriction enzyme analysis. The method has proved to be very sensitive, with a detection limit of 20 fg of TBEV RNA per PCR run, or a single positive tick. Based on biostatistical considerations a sample size of at least 1000 ticks per estimation point was chosen. The estimated TBEV prevalence and confidence intervals (CI) were calculated from the nRT-PCR results of pooled samples (10 adults or 20 nymphs) using appropriate formulae for pooled testing. In order to identify the estimated TBEV prevalence as well as to assess the influence of annual and seasonal factors on TBEV prevalence, ticks were sampled twice a year (May and September) in 1997 and 1998 at exactly identical sites. These sites were selected because they were known to have had the highest incidence of autochthonous TBE cases during the previous 10 years. On sampling days, relevant local meteorological data were also noted. In total, 8500 I. ricinus ticks were investigated in this study, 4270 (3540 nymphs, 730 adults) from the Black Forest habitats, and 4230 (3680 nymphs, 550 adults) from the Bavarian locations. In the foci near Freiburg (Black Forest), the estimated virus prevalence was relatively high in the whole tick population, during 1997 with only slight seasonal differences [3.4% (confidence interval, CI, 2.3-4.8%) in May and 2.9% (CI 1.7-4.5%) in September]. In contrast, in 1998, in the same foci the estimated TBEV prevalence was considerably lower [1.1% (CI 0.5-2.0%) in May and 0.6% (CI 0.2-1.4%) in September]. Thus, while the seasonal differences again remained low, the annual variation was marked. In the Bavarian foci in 1997, the estimated virus prevalence of the whole tick population studied was lower than in the Black Forest foci and the seasonal fluctuations were low: in May 1997 0.9% (CI 0.4-1.8%) of the ticks were positive, in September 1.1% (CI 0.5-1.9%). In 1998, in May 2.0% (CI 1.1-3.3%) of the ticks were positive, and in September 1.1% (CI 0.5-2.1%). For the whole study period, every 50th to 100th I. ricinus nymph or adult in the Passau region was calculated to give a positive signal in the nRT-PCR. The TBEV prevalence data indicate that residents and visitors of areas in Germany known for high endemic activity take a significant risk of contracting TBEV infection, if bitten by ticks. In addition, the data suggest that annual fluctuations may exist in the whole tick population studied. Seasonal fluctuations of the virus prevalence in ticks were small.
TL;DR: A comprehensive Lyme borreliosis risk assessment process was applied in S. Rossore Estate, on the Tyrrhenian coast, near Pisa, Italy, and in spite of high levels of tick exposure, B. burgdorferi sl specific antibodies were not detected in sera from Estate personnel and sentinel animals.
Abstract: A comprehensive Lyme borreliosis risk assessment process was applied in S. Rossore Estate, on the Tyrrhenian coast, near Pisa, Italy. Host-seeking Ixodes ricinus nymphs peaked in May in oak-dominated deciduous wood (median, Q1–Q3, number of nymphs/50 m dragging = 4.5, 2.5–8), whereas host-seeking larvae peaked in August in the same habitat type (6.0, 4–17/50 m dragging). Prevalence of I. ricinus infestation was 88.9% in wild rodents (n = 11), 64.3% in fallow deer (n = 28) and 0.0% in wild boars (n = 5). Borrelia burgdorferi sensu lato was not isolated from rodents' organs, and from 80 I. ricinus nymphs and 50 adults. Moreover, PCR for B. burgdorferi sl carried out on 110 nymphs and 12 adult ticks also gave negative results. Forest workers were at higher risk of tick bite than other Estate employees (relative risk (RR): 1.7, p = 0.02). In spite of high levels of tick exposure, B. burgdorferi sl specific antibodies were not detected in sera from Estate personnel (n = 30) and sentinel animals (dogs, n = 23, fallow deer, n = 61).
TL;DR: It is concluded that most dogs in this study developed an antibody response against Borrelia burgdorferi sensu lato after their first tick infestation and were thereafter repeatedly immunologically stimulated, probably reinfected, during the consecutive tick seasons.
Abstract: Summary Thirty‐three family dogs were monitored for antibodies to Borrelia burgdorferi sensu lato over a 3‐year period. Serum samples were collected before and during the season of high tick activity. Antibody levels were measured with an ELISA based on whole‐cell antigens and an ELISA with a purified recombinant flagellin (r 410). Antibody levels measured with the whole‐cell ELISA increased after the first exposure to ticks. Following the first seasonal period of tick quiescence, antibody levels decreased, and subsequently increased again in the second tick season. Thereafter whole‐cell ELISA titres persisted at moderate levels and did not decrease between tick seasons. The recombinant flagellin ELISA did not show a strong response in the first tick season, but did in the second tick season and levels of antibodies continued to fluctuate thereafter. We conclude that most dogs in this study developed an antibody response against Borrelia burgdorferi sensu lato after their first tick infestation and were t...