Showing papers on "Ixodes ricinus published in 2003"

Association of Borrelia garinii and B. valaisiana with songbirds in Slovakia

Abstract: In Europe, 6 of the 11 genospecies of Borrelia burgdorferi sensu lato are prevalent in questing Ixodes ricinus ticks. In most parts of Central Europe, B. afzelii, B. garinii, and B. valaisiana are the most frequent species, whereas B. burgdorferi sensu stricto, B. bissettii, and B. lusitaniae are rare. Previously, it has been shown that B. afzelii is associated with European rodents. Therefore, the aim of this study was to identify reservoir hosts of B. garinii and B. valaisiana in Slovakia. Songbirds were captured in a woodland near Bratislava and investigated for engorged ticks. Questing I. ricinus ticks were collected in the same region. Both tick pools were analyzed for spirochete infections by PCR, followed by DNA-DNA hybridization and, for a subsample, by nucleotide sequencing. Three of the 17 captured songbird species were infested with spirochete-infected ticks. Spirochetes in ticks that had fed on birds were genotyped as B. garinii and B. valaisiana, whereas questing ticks were infected with B. afzelii, B. garinii, and B. valaisiana. Furthermore, identical ospA alleles of B. garinii were found in ticks that had fed on the birds and in questing ticks. The data show that songbirds are reservoir hosts of B. garinii and B. valaisiana but not of B. afzelii. This and previous studies confirm that B. burgdorferi sensu lato is host associated and that this bacterial species complex contains different ecotypes.

Shift of the tick Ixodes ricinus and tick-borne encephalitis to higher altitudes in central Europe.

Abstract: In the last decade a significant increase in the number of cases of human tick-borne encephalitis (TBE) has been registered in the Czech Republic [1]. Roughly, this increase could be characterized as twofold for the 1993– 2001 period compared with the 1984–1992 period (5,240 vs. 2,441 cases). A similar increase in the incidence of human TBE has been observed in some other European countries during the 1990s, as reported on the website http://www.tbe-info.com/epidemiology/index.html. The increase in the incidence of TBE in the Czech Republic has been manifested in three ways: (i) a higher number of cases in areas well known for TBE in humans [1]; (ii) a re-emergence of TBE in areas where it had previously occurred but had not or only sporadically been observed since the 1970s [2], or (iii) the emergence of TBE in places where it had not been known to occur previously. TBE is notoriously dependent on the presence of the major vector of the virus, the Ixodes ricinus tick. In Central Europe, the upper limit of this tick’s geographical habitat was found to be 700 m above sea level (a.s.l.), based on the results of tick collections covering the whole territory of the Czech Republic [3]. These findings were verified in a long-term (1981–1983) field experiment studying the developmental cycle of the Ixodes ricinus tick in different altitudes in the Giant Mountains (KrkonoÐe National Park) [4, 5]. This study found that ticks were not able to finish their developmental cycle at an altitude higher than 700 m a.s.l. Due to the protracted unfavorable conditions at higher altitudes, the duration of tick development was extended in such way that their energy supply was exhausted. Therefore, ticks at various developmental stages experimentally introduced to this altitude died before finishing their development, and no stable population could be established. These results correlated with all other findings in the Czech Republic. During the 1990s, however, a shift of the limit of Ixodes ricinus distribution and tick-borne diseases towards higher latitudes was observed in Sweden, and was discussed as being a result of climate modification during this period [6, 7]. Simultaneously, at the end of the same decade, the Czech health service announced that, in addition to finding higher numbers of ticks at low altitudes, Ixodes ricinus was appearing more frequently around the 700 m a.s.l. mark in sites where it formerly occurred only negligibly; Ixodes ricinus was also appearing for the first time at higher altitudes, where ticks were previously unknown. Therefore, we focused our attention on the region of southern Bohemia, where human cases of TBE are most frequent, and we carried out a follow-up study of the vertical distribution of Ixodes ricinus in the umava Mountains, a region that borders the Czech Republic, Germany and Austria, where 85% of the land is covered by forests and the altitude reaches >1300 m a.s.l. The present study was performed in 2001 in cooperation with the staff of the umava National Park. From April to October, 54 staff members checked regularly for the presence of ticks in 67 dogs in service. A total of 61 dogs were infested with 1–25 ticks/dog/season. Over 400 Ixodes ricinus ticks (nymphs and adults) were found on dogs permanently living and moving about at an elevation of 1,000—1,100 m a.s.l.; six dogs living over 1,100 m a.s.l. were not infested. In 2002, we confirmed the existence of local Ixodes ricinus populations by flagging for host-seeking ticks in areas where dog infestations had occurred the previous year (up to 1,100 m a.s.l.). The research presented here has been funded by the project Climate Change Adaptation Strategies for Human Health (cCASHh), Contract Nr. EVK2-2000-0070

Relapsing Fever-Like Spirochetes Infecting European Vector Tick of Lyme Disease Agent

Abstract: To determine whether relapsing fever–like spirochetes associated with hard ticks may infect Ixodes ricinus ticks in central Europe, we screened questing ticks for 16S rDNA similar to that of Asian and American relapsing fever–like spirochetes. We compared the prevalence of these spirochetes to that of Lyme disease spirochetes transmitted by the same vector. Relapsing fever-like spirochetes infect 3.5% of questing vector ticks in our three central European sites near the Rhein Valley. These spirochetes differ genetically from their American and Asian analogs while being relatively homogeneous in the region we sampled. The Lyme disease genospecies most commonly detected in central Europe are distributed broadly, whereas those that are less frequently found appear to be place-specific. The absence of co-infected ticks suggests that relapsing fever–like and Lyme disease spirochetes may not share hosts. Exposure risk for relapsing fever–like spirochetes is similar to that of certain Lyme disease genospecies. Although many persons may be bitten by ticks infected by relapsing fever–like spirochetes, health implications remain unknown.

Molecular phylogenetic analyses indicate that the Ixodes ricinus complex is a paraphyletic group.

Abstract: The Ixodes ricinus species complex is a group of ticks distributed in almost all geographic regions of the world. Lyme borreliosis spirochetes are primarily transmitted by tick species within this complex. It has been hypothesized that the Lyme vector ticks around the world are closely related and represent a monophyletic group. This implies that vector competence in ixodid ticks for Lyme agents might have evolved only once. To test this hypothesis, we used a molecular phylogenetic approach. Two fragments of mitochondrial 16S ribosomal deoxyribonucleic acid were sequenced from 11 species in the I. ricinus complex and from 16 other species of Ixodes. Phylogenetic analysis using Bayesian methodology indicated that the I. ricinus complex is not a monophyletic group unless 3 additional Ixodes species are included in it. The known major vectors of Lyme disease agents in different areas of the world are not sister taxa. This suggests that acquisition of the ability to transmit borreliosis agents in species of I...

Bartonella henselae in Ixodes ricinus ticks (Acari: Ixodida) removed from humans, Belluno province, Italy.

Abstract: The potential role of ticks as vectors of Bartonella species has recently been suggested. In this study, we investigated the presence of Bartonella species in 271 ticks removed from humans in Belluno Province, Italy. By using primers derived from the 60-kDa heat shock protein gene sequences, Bartonella DNA was amplified and sequenced from four Ixodes ricinus ticks (1.48%). To confirm this finding, we performed amplification and partial sequencing of the pap31 protein and the cell division protein ftsZ encoding genes. This process allowed us to definitively identify B. henselae (genotype Houston-1) DNA in the four ticks. Detection of B. henselae in these ticks might represent a highly sensitive form of xenodiagnosis. B. henselae is the first human-infecting Bartonella identified from Ixodes ricinus, a common European tick and the vector of various tickborne pathogens. The role of ticks in the transmission of bartonellosis should be further investigated.

The relationships between habitat topology, critical scales of connectivity and tick abundance Ixodes ricinus in a heterogeneous landscape in northern Spain

Abstract: The habitat mosaic was used to quantify connectivity between patches of different tick density of the notorious tick species Ixodes ricinus in an attempt to determine the cause of variations in tick abundance among apparently homogeneous sites in northern Spain. The analysis revealed that patches with high tick abundance are stepping-stone territories that, when removed from the landscape, cause large changes in connectivity. Sites with medium tick abundance do not cause such a critical transition in connectivity. Patches with low tick abundance, but optimal abiotic conditions for survival, are located within the minimum cost corridors network joining the patches. while those sites where the tick has been intermittently collected are located at variable distances from this network. Sites where the tick is consistently absent, but where the habitat is predicted to be suitable (old, heterogeneous forests of Quercus spp.) for the tick, are very separated from this main network of connections. These results suggest that tick distribution in a zone is highly affected not only by abiotic variables (vegetation and weather) but also by host movements. Dispersal of the tick is a function of how the hosts perceive the habitat, and the habitat's permeability to host movement. Permanent tick populations seem to be supported by the existence of these critical, high density patches, located at significant places within the habitat network. Dept of Parasitology, Veterinary Fac., Miguel Servet 177, 50013 Zaragoza, Spain.

High Diversity of ankA Sequences of Anaplasma phagocytophilum among Ixodes ricinus Ticks in Germany

Abstract: In Germany humans with acute granulocytic ehrlichiosis have not yet been described. Here, we characterized three different genes of Anaplasma phagocytophilum strains infecting German Ixodes ricinus ticks in order to test whether they differ from strains in other European countries and the United States. A total of 1,022 I. ricinus ticks were investigated for infection with A. phagocytophilum by nested PCR and sequence analysis. Forty-two (4.1%) ticks were infected. For all positive ticks, parts of the 16S rRNA and groESL genes were sequenced. The complete coding sequence of the ankA gene could be determined in 24 samples. The 16S rRNA and groESL gene sequences were as much as 100% identical to known sequences. Fifteen ankA sequences were ≥99.37% identical to sequences derived from humans with granulocytic ehrlichiosis in Europe and from a horse with granulocytic ehrlichiosis in Germany. Thus, German I. ricinus ticks most likely harbor A. phagocytophilum strains that can cause disease in humans. Nine additional sequences were clearly different from known ankA sequences. Because these newly described sequences have never been obtained from diseased humans or animals, their biological significance is currently unknown. Based on this unexpected sequence heterogeneity, we propose to use the ankA gene for further phylogenetic analyses of A. phagocytophilum and to investigate the biology and pathogenicity of strains that differ in the ankA gene.

Detection and Identification of Pathogens and Host DNA in Unfed Host-Seeking Ixodes ricinus L. (Acari: Ixodidae)

Abstract: In this study, we have developed molecular methods for the identification of reservoir hosts of sylvatic tick-borne zoonoses. The methods are based on the analysis of the blood meal remnant in the tick gut and include detection of pathogens and identification of the host origin of the blood meal. For host identification, a universal primer pair was used to amplify part of the vertebrate 18S rRNA gene followed by reverse line blot hybridization using subgroup-specific probes. Analyses of DNA from whole blood of vertebrates identified the correct subgroup of a broad range of vertebrate species (e.g., Ruminantia, Leporidea, Canidae, Murinae, Arvicolinae, Insectivora, Galliformes, Passeriformes) using probes based on the 18S rDNA sequences. Host DNA in the remnants of larval blood meals was detected in the gut of Ixodes ricinus nymphs maintained under natural conditions up to 9 mo after molting. For pathogen identification, a multiplex polymerase chain reaction was used that targeted parts of the 18S rRNA gene of piroplasm protozoa, the 16S rRNA gene of bacteria, and the intergenic spacer of the Borrelia burgdorferi genospecies complex. The utility of both methods was demonstrated under laboratory conditions by detecting Babesia microti (Franca) and gerbil DNA in 3-mo-old I. ricinus nymphs that had fed on B. microti-infected gerbils as larvae, and under field conditions by analyzing unfed ticks that were collected in a forest. The field study showed that the majority of ticks had fed on ruminants or birds and few on rodents, which is in accord with our knowledge of the fauna in this forest. Few pathogens were detected but the discovery of Borrelia valaisiana and B. burgdorferi s.s. in ticks that had fed on deer and Borrelia afzelii in a tick that had fed on a bird raises questions about the mode of transmission of these spirochetes and possibly about their host specificity.

Distribution of the common tick, Ixodes ricinus (Acari: Ixodidae), in different vegetation types in southern Sweden.

Abstract: The aim of this study was to investigate whether differences in Ixodes ricinus (L.) nymphal relative density exist among different vegetation types in southern Sweden. Nymphal I. ricinus were sampled in southeastern Scania in southern Sweden during JuneÐAugust 1997. A total of 110 Ð180 25-m 2 samples were taken by blanket-dragging from each of nine different vegetation types. There was a highly signiÞcant difference in nymphal abundance between the open areas as one group and the forested areas as another group (P 0.0001). Vegetation types that differed signiÞcantly in median nymphal abundance from all other vegetation types were pine forest (16 nymphs/100 m 2 ) and beech forest (40 nymphs/100 m 2 ). No signiÞcant differences in median nymphal density were revealed among mixed deciduous forest, alder forest, oak forest, and hazel forest (28 Ð32 nymphs/100 m 2 ), or among dry meadow, meadow, and heath (0 nymphs/100 m 2 ). Forestation of open areas is likely to lead to increased I. ricinus abundance and disease risk.

Identifying disease reservoirs in complex systems: mountain hares as reservoirs of ticks and louping-ill virus, pathogens of red grouse

Abstract: Summary 1 We examined the role of mountain hares in the louping-ill virus/Ixodes ricinus tick system to determine whether hares were reservoirs of these pathogens for red grouse. A field experiment, which involved reducing mountain hare densities was undertaken and changes in tick abundance, louping-ill virus seroprevalence and red grouse densities recorded. 2 Hares were found to be important hosts for all stages of ticks at two study sites and, where sheep were frequently treated with acaricide, hares fed the greatest proportion of adult ticks. Hare densities were reduced at the experimental site between 1993 and 2001 but remained relatively constant at a control site. Both nymph and larvae tick burdens on red grouse chicks declined over this period to very low levels at the treatment site, but not at the control site. The estimated size of the tick population at the treatment site decreased by more than 99% by 1999. 3 Louping-ill prevalence, as measured by antibody prevalence in shot young red grouse, also declined at the treatment site, lagging behind the tick decline by approximately 2 years. The number of young grouse produced per hen grouse at this treatment site increased in comparison to a second control area. However, no change was found in summer grouse densities and thus we cannot demonstrate parasite-mediated competition. 4 A deterministic SIR-type model describing the dynamics of this pathogen/vector/host system was constructed and used to examine the role of mountain hares in louping-ill virus and tick dynamics. The model predicted a decline in tick numbers and seroprevalence as hare densities reduced. The inclusion of hares as both tick hosts and vector–host–vector transmitters of louping-ill virus gave the best fit to the observed data.

Molecular Evidence of Coinfection of Borrelia burgdorferi Sensu Lato, Human Granulocytic Ehrlichiosis Agent, and Babesia microti in Ticks From Northwestern Poland

Abstract: To assess the potential risk for tick-borne agents, Ixodes ricinus were collected from 2 sites in northwestern Poland. The ticks were tested by polymerase chain reaction for coinfection with Borrelia burgdorferi sensu lato (s. l.), human granulocytic ehrlichiosis (HGE) agent, and Babesia microti. Of the 533 processed ticks, 16.7% were positive for B. burgdorferi s. l., 13.3% for B. microti, and 4.5% for the HGE agent. Twenty ticks were coinfected with 2 or 3 of the pathogens.

Host-seeking activity of ixodid ticks in relation to weather variables.

Abstract: Ixodid ticks were monitored in a temperate deciduous broad-leaved forest in South Moravia (Czech Republic). Relative abundance of the ticks collected before noon (10.00-12.00 h) was compared to several weather variables (air and soil temperatures, relative humidity, precipitation, wind speed, and derived values) using the Pearson correlation coefficient. The tick numbers were found to be most closely related to the amplitude of the soil (-5 cm) temperature between 07 h and 14 h (TSamp, in Ixodes ricinus), and the soil temperature (TS) at noon (in Haemaphysalis concinna) or in the morning (Dermacentor reticulatus). While a growing amplitude in TSamp caused an increased host-seeking activity of I. ricinus and H. concinna, it suppressed the activity of D. reticulatus, a tick species mainly occurring in colder seasons of the year in Central Europe. The air temperature (TA) and relative humidity (RH) were also closely related to the tick activity, whereas rainfall and wind speed remained largely uncorrelated with the activity of the three tick species. Multiple linear regression on several variables (TSamp, TA, TS, TA-TS, RH) explained 48% of the variance in I. ricinus, 47% in H. concinna, and 38% in D. reticulatus. Predictive two-variable regression models of relative abundance in host-seeking ticks were based on morning temperature (TA or TS) and morning RH as the most important environmental factors: they explained 32% (I. ricinus), 39% (H. concinna), and 35% (D. reticulatus) of the variance. Journal of Vector Ecology 28 (2): 159-165. 2003.

Genetic Diversity of Bacterial Agents Detected in Ticks Removed from Asymptomatic Patients in Northeastern Italy

Abstract: A total of 360 ticks were removed from 353 asymptomatic subjects in Belluno Province, Italy and surrounding areas, from 1998 to 2001. Ticks were identified as Ixodes ricinus (357), Ixodes hexagonus (1), Rhipicephalus sanguineus (1), and Ixodes ventalloi (1). Tick DNA was investigated by PCR and subsequent sequencing of amplified products to identity associated bacterial agents. Primers targeting different genes of Rickettsia (gltA and OmpA), Borrelia (16S rDNA, rpoB), Francisella (16S rDNA), and all genera members of the Anaplasmataceae (16S rDNA), were used. DNA of bacterial agents was identified in 28 Ixodes ricinus specimens (7.8%). Rickettsia helvetica was detected in 7 ticks. Rickettsia sp. IRS4 and Borrelia afzelii was detected in 4 ticks each. B. garinii and B. valaisiana were identified in one tick each. Anaplasma phagocytophilum, the agent of human granulocytic ehrlichiosis, was identified in 1 specimen of I. ricinus. A new Ehrlichia sp. (‘Candidatus Ehrlichia walkerii’, sp. nov.) was identified in 10 I. ricinus specimens.

First isolation and characterization of Borrelia burgdorferi sensu lato strains from Ixodes ricinus ticks in Turkey.

Abstract: In order to investigate the presence and prevalence of Lyme borreliosis (Lyme disease) Borrelia species, 312 unfed ticks were collected by flagging at a woodland area in Trakya, in the European side of Turkey, in May 2002. Twelve of 299 Ixodes ricinus ticks were infected with Borrelia spp., as determined by cultivation in BSK medium (prevalence rate 4.0 %). Ten pure cultures were subjected to further characterization by sequencing analysis of the 5S–23S rDNA intergenic spacer, 16S rDNA and flagellin gene. One isolate of Borrelia burgdorferi sensu stricto, two of Borrelia garinii (Eurasian type), two of Borrelia afzelii, four of Borrelia lusitaniae and one of Borrelia valaisiana were identified. However, no Asian-type B. garinii was found. Interestingly, all Borrelia species that are known to be carried by I. ricinus were discovered among the 10 isolates. These results provide the first evidence for the existence of the Lyme borreliosis agent in Turkey.

Prevalence of Four Species of Borrelia burgdorferi Sensu Lato and Coinfection with Anaplasma phagocytophila in Ixodes ricinus Ticks in Central Germany

Abstract: A total of 305 Ixodes ricinus ticks collected from three areas of Thuringia in central Germany were investigated for infection with Borrelia burgdorferi sensu lato species and Anaplasma phagocytophila. Overall, 11.1% were infected with Borrelia burgdorferi and 2.3% with Anaplasma phagocytophila. Adult ticks showed a significantly higher rate of infection with both borreliae and Anaplasma phagocytophila. Borrelia garinii (55.9%) was detected most frequently, followed by Borrelia burgdorferi sensu stricto (32.4%), Borrelia afzelii (17.6%), and Borrelia valaisiana (5.9%). Four ticks had dual infection with Borrelia garinii and Borrelia burgdorferi sensu stricto. Two of the Borrelia-positive ticks were coinfected with Anaplasma phagocytophila.

Molecular evidence for anaplasma phagocytophilum and borrelia burgdorferi sensu lato in ixodes ricinus ticks from eastern slovakia

Abstract: Ixodes ricinus ticks (20 males, 20 females and 20 nymphs) collected in Kooice, Slovakia were examined for the presence of Anaplasma phagocytophilum and Borrelia burgdorferi sensu lato (s.l.) by PCR. 38.3% of the tested ticks carried single infection of B. burgdorferi s.l. and 8.3% were infected with A. phagocytophilum. Double infection of both pathogens was detected in 5% of tested ticks. These results indicate that both B. burgdorferi s.l. and A. phagocytophilum co-circulate in the enzootic sites of Eastern Slovakia and may cause co-infection in humans.

First isolation of Borrelia burgdorferi sensu lato from Ixodes ricinus ticks in Morocco.

Abstract: To determine the infection rate of Ixodes ricinus (I. ricinus) ticks with Borrelia burgdorferi sensu lato (B. burgdorferi sl) and to assess the frequency of the individual Borrelia species in this tick species, a total of 295 I. ricinus were collected in Taza region (Northeast of Morocco), from January to June 2002. The presence of B. burgdorferi sl was determined by direct fluorescence antibody assay (DFA) and by PCR after culture. B. burgdorferi sl isolates were identified at the species level by restriction fragment length polymorphism analysis of amplified products. The mean rate of I. ricinus infection with B. burgdorferi sl was 47.8%. Isolation attempts in BSK II medium resulted in 26 pure isolates. However, PCR performed on culture medium allowed to identify 82 Borrelia DNAs. B. lusitaniae has been identified from 76 out of 82 infected I. ricinus ticks (92.7%). Three ticks were infected by B. burgdorferi ss, and three other ticks were infected by B. garinii. This is the first report of the presence of B. burgdorferi sl in Morocco and more specifically of B. burgdorferi ss in North Africa.

Candidatus Ehrlichia Walkerii

Abstract: Ixodes ricinus harbors many infectious agents pathogenic for humans. A cause of fever is found in less than 50% of patients exposed to ticks. Investigations on 359 Ixodes ticks removed from asymptomatic patients in Northern Italy revealed the presence of a new ehrlichial agent in 10 ticks. Comparison of the 16S rRNA and the gltA gene sequences showed the organism is most closely related to Ehrlichia ruminantium. We propose this new Ehrlichia be named ‘candidatus Ehrlichia walkerii.’

Borrelia burgdorferi s.l. in Ixodes ricinus (Acari: Ixodidae) Ticks Collected from Vegetation and Small Rodents in Recreational Areas of the City of Poznań

Abstract: During 1998–1999, Ixodes ricinus (L.) populations were investigated in three different biotopes (deciduous, mixed, coniferous forest) situated in popular recreational areas in Poznan, Poland. In total, 1,123 questing ticks (1,002 nymphs, 69 males, 52 females) were collected by flagging vegetation. Additionally, in 1998 between May and September small rodents were trapped and inspected for feeding ticks. Altogether, 213 rodents of three species: Apodemus agrarius Pall., A. flavicollis Melchior, Clethrionomys glareolus Schreber were captured. Of 323 engorged ticks, 304 were larvae and 19 nymphs. All ticks collected from vegetation, as well as from rodents were examined for the presence of Borrelia burgdorferi Johnson, Schmid, Hyde, Steigenwalt & Brenner s.l. spirochetes by indirect immunofluorescence assay (IFA) using PAB 1B29. The seasonal pattern of activity of questing I. ricinus was always bimodal (May/June and August/September). The most abundant tick population occurred in the deciduous fores...

Anaplasma phagocytophila as an Abortifacient Agent in Sheep Farms from Northern Spain

Abstract: Abortions are the cause of important economic losses in sheep farms. The etiology is diverse, and most of the abortifacient agents are zoonotic pathogens. One of these is Anaplasma phagocytophila (formerly Ehrlichia phagocytophila ) that parasitizes granulocytes and monocytes in domestic ruminants in several countries in Europe causing a syndrome called tick-borne fever (TBF). The disease is characterised by high fever, rickettsemia (infected neutrophils), neutropenia, reduced milk yield, and abortion in nonimmune pregnant animals. TBF is known to have profound effects on the immune system and can increase the susceptibility to disease. 1,2 Presence of TBF in Northern Spain (Basque Country) was first described in 1986, 3 and since then, this agent has been associated with ovine abortions in several mountainous areas.

Longitudinal surveillance of the tick Ixodes ricinus for borreliae.

Abstract: Host-seeking Ixodes ricinus (L.) (Acari: Ixodidae) were monitored for borreliae (Borrelia burgdorferi s.l.) using dark-field microscopy in South Moravia (Czech Republic) each May from 1991 to 2001 (150 nymphs, 100 females and 100 males each year). This survey revealed a mean annual percentage of infected ticks of 16.8% (range, 11.7-24.2) in nymphs, 24.9% (range, 16.5-33.6) in females and 26.1% (range, 17.1-37.3) in males. Annual incidence of Lyme borreliosis in humans of the area in the same period (range, 8.7-41.7 per 100,000) correlated significantly with the frequency (number of ticks per flag per hour) of nymphs infected with >50 borreliae or all nymphal ticks, but not with the frequency of females, infected females or the infection rate (% of ticks infected) of either nymphal or female ticks. A prediction of the annual incidence of Lyme borreliosis, based on the frequency of heavily infected or all nymphal I. ricinus ticks, is feasible. The infection rate in I. ricinus correlated significantly with the North Atlantic Oscillation winter index of the last year (in nymphs) or of the year before last (in adults).

Causes of febrile illnesses after a tick bite in Slovenian children.

Abstract: Background To establish the etiology in Slovenian children with febrile illnesses occurring after a tick bite. Methods Eighty-six febrile patients younger than 15 years referred to our institution in 2001 with a history of a tick bite within 6 weeks before onset of the illness were included in this prospective study. Acute and convalescent serum samples were tested for the presence of antibodies to tick-borne encephalitis virus, Borrelia burgdorferi sensu lato, Anaplasma phagocytophilum, Ehrlichia chaffeensis, Rickettsia conorii, Babesia microti, Bartonella henselae, Bartonella quintana and Francisella tularensis. Cerebrospinal fluid was investigated in patients in whom meningeal involvement was clinically suspected. Blood and/or cerebrospinal fluid from the patients were cultured in modified Kelly-Pettenkofer medium. PCR was performed to detect ribosomal DNA of A. phagocytophilum and E. chaffeensis. Results Of 86 patients 33 (38%) were excluded because a well-defined febrile illness not associated with tick bite was established. Tick-borne illness was diagnosed in 28 (53%) of the 53 remaining patients. The most common diagnosis was tick-borne encephalitis (64%), followed by Lyme borreliosis (46%), human monocytic ehrlichiosis and human granulocytic ehrlichiosis (serologic evidence of infection in 9 and 4%, respectively). In 6 (21%) patients there was evidence for infection with more than 1 tick-borne agent. Conclusions Tick-borne illness was established in 53% of the patients younger than 15 years presenting with febrile illness occurring within 6 weeks after a tick bite. The most common identified illnesses were tick-borne encephalitis and Lyme borreliosis.

Distribution and prevalence of Borrelia burgdorferi sensu lato in Ixodes ricinus ticks of canton Ticino (Switzerland).

Abstract: Free-living Ixodes ricinus ticks were collected from 12 different sites of canton Ticino, south of the Alps (Switzerland). Each tick was examined for the presence of Borrelia burgdorferi sensu lato (sl), the etiologic agent of Lyme borreliosis using direct fluorescent antibody assay, and isolation of the bacteria. Borreliae were characterized by PCR followed by RFLP. The abundance and infection rates of I. ricinus ticks varied greatly between the areas. Two localities were found free of Borrelia. The prevalence of infected ticks ranged from 5 to 19%. Most ticks (96%) were found infected by < 50 spirochetes. Three B. burgdorferi sl species were successfully isolated: B. garinii dominated, followed by B. lusitaniae and B. valaisiana. Additionally, a mixed infection with B. garinii and B. valaisiana was observed. The distribution of the various Borrelia species in the different areas was heterogeneous. This is the first report of the presence of B. lusitaniae in I. ricinus in Switzerland.

The molecular evidence of Babesia microti infection in small mammals collected in Slovenia.

Abstract: In Europe, the zoonotic cycle of Babesia microti has not been determined so far. Recently, B. microti was detected in Ixodes ricinus ticks in Slovenia by using molecular methods. In order to investigate the mammalian hosts of B. microti in Slovenia we collected 261 small mammals representing 11 species. They were tested for the presence of babesial parasites with a PCR assay based on the nuclear small subunit rRNA gene (nss-rDNA). The bank vole (Clethrionomys glareolus) and yellow-necked mouse (Apodemus flavicollis) were infected with B. microti. The prevalence rate was 15·9% for C. glareolus and 11·8% for A. flavicollis. Nucleotide sequences of amplified portions of B. microti nss-rDNA from C. glareolus and A. flavicollis were indistinguishable from each other and identical with those previously described in I. ricinus ticks collected in Slovenia. The results of this study represent molecular evidence of B. microti in small mammals in Europe.

Detection of Astrakhan fever rickettsia from ticks in Kosovo.

Abstract: Astrakhan fever is a summer spotted fever resembling Mediterranean spotted fever, endemic in Astrakhan, a region of Russia located by the Caspian sea. Its agent is a spotted fever group rickettsia, member of the Rickettsia conorii complex, transmitted to humans by Rhipicephalus sanguineus and Rhipicephalus pumilio ticks. In Summer 2001, French United Nations troops in Kosovo collected 2 ticks on asymptomatic soldiers (1 R. sanguineus and 1 Hyalomma marginatum) and 10 ticks on dogs (7 R. sanguineus, 2 Ixodes ricinus, and 1 H. marginatum) in the Morina region. By PCR amplification of both the gltA and ompA genes, we detected a rickettsia in 4 R. sanguineus, i.e., 3 of those collected on dogs and those taken from military personnel. As ticks were preserved in alcohol, culture was not possible. The sequences obtained from these PCR products identified, with a 100% homology, Astrakhan fever rickettsia. None of the other collected tick species was positive. The patient with the positive tick remained asymptomatic. Our study demonstrates, for the first time, the presence of Astrakhan fever rickettsia in ticks outside Russia. We suspect that the area of distribution of this rickettsia could be wider than initially suspected. Moreover, as R. sanguineus ticks bite humans, Astrakhan fever might be a cause of spotted fever in Kosovo.

Transmission of Anaplasma phagocytophilum to Ixodes ricinus Ticks from Sheep in the Acute and Post-Acute Phases of Infection

Abstract: A total of 60 sheep were exposed to Anaplasma phagocytophilum infection on an enclosed area of Ixodes ricinus-infested pasture in North Wales, United Kingdom, and rapidly acquired acute A. phagocytophilum infections detectable by PCR and blood smear examination. Of the ticks that had engorged in the previous instar on infected sheep, 52% of adult ticks and 28% of nymphs were PCR positive; a significant, 10-fold increase in prevalence compared to that of ticks that engorged on sheep preinfection was observed (P = 0.015). The likelihood that ticks were PCR positive, after feeding on the sheep and molting to the next instar, increased marginally with increasing numbers of infected neutrophils per milliliter of blood of their sheep host (P = 0.068) and increased significantly when they were collected from sheep carrying higher numbers of adult female ticks (P = 0.017), but increasing numbers of feeding nymphs had a significant negative effect on transmission (P = 0.049). The numbers of circulating neutrophils and of infected neutrophils also varied significantly with the numbers of ticks feeding on the sheep when the blood was collected. Our study suggests that ruminants are efficient reservoirs of A. phagocytophilum during the acute and post-acute phases of infection. The risk of ruminant-derived infections may, however, be strongly affected by variations in tick densities, which may influence transmission from acutely infected animals via effects on the numbers of infected cells in the blood and possibly by within-skin modulation of infection.