Diversity in prevalence and genospecies of Borrelia burgdorferi sensu lato in Ixodes ricinus ticks and rodents in Lithuania and Norway

A total of 1679 questing Ixodes ricinus ticks collected in Lithuania and 535 I. ricinus ticks collected in Norway from locations with different habitats were investigated for the presence of Borrelia burgdorferi sensu lato. In Lithuania, 223 ticks (13.3%) were infected with B. burgdorferi s.l., and in Norway, 28 ticks (5.2%). The highest prevalence of B. burgdorferi s.l was found in deciduous and mixed forests (19.4% in Lithuania, 8.6% in Norway). A lower prevalence was determined in pine forests (8.6% in Lithuania) and costal zones (4.3% in Norway), and the least prevalence was found in grasslands (2.5% in Lithuania, 1% in Norway). A total of 398 rodents belonging to 9 species were live-captured in Lithuania and Norway. Prevalence of B. burgdorferi s.l. in rodents varied between species and sampling sites in both countries. In Lithuania, the prevalence of infection was higher in Microtus arvalis (range 25–57% in different sampling sites) and in Myodes glareolus (range 14–71%) than in Apodemus flavicollis (range 0–37%) and in A. agrarius (range 11–33%). In Norway, the prevalence of B. burgdorferi s.l. in rodents was lower (range from 5% in A. sylvaticus to 6% in A. flavicollis). B. afzelii was the predominant genospecies in ticks and rodents in Lithuania and Norway. In Lithuania, B. afzelii was found in 76%, B. garinii in 10%, B. burgdorferi sensu stricto in 7%, and Borrelia spp. in 6% of infected ticks. Double infections were observed in 1% of the infected ticks. In Norway, B. afzelii was found in 68%, B. garinii in 21%, and B. burgdorferi s.s. in 11% of infected ticks. All infected rodents from both countries hosted B. afzelii genospecies. Only the red squirrel (Sciurus vulgaris) harbored both B. afzelii and B. burgdorferi s.s.     

Prevalence of avian-associated Borrelia burgdorferi s.l. genospecies in Ixodes ricinus ticks collected from blackbirds (Turdus merula) and song thrushes (T. philomelos)

Between May and September of 2002, forest passerine birds and immature Ixodes ricinus ticks infesting them were surveyed for infection with Borrelia burgdorferi s.l. in a sylvatic habitat in west-central Poland. A total of 738 feeding I. ricinus ticks were recovered from 114 birds belonging to 9 species. The majority of ticks (65.7%) were collected from two thrush species, the blackbird (Turdus merula) and the song thrush (T. philomelos). Since only the two Turdus species proved to be parasitized by Borrelia-infected ticks, this study focused mainly on these birds. Immature ticks were removed from 53 of the 54 captured thrushes. A total of 304 partially or fully engorged ticks (110 larvae and 194 nymphs), and 53 bird-derived blood samples were tested for borreliae. B. burgdorferi s.l. DNA was detected by PCR in 11% of the larval ticks and in 7.2% of the nymphs. The PCR-positive ticks were found on 8 of 53 tick-infested thrushes. B. garinii and B. valaisiana accounted for 88.5% and 11.5% of the infections detected in Borrelia-positive ticks, respectively. Only one out of 53 of Turdus blood samples were PCR-positive for borreliae. The blood-positive thrush was infected with B. burgdorferi s.s. B. afzelii was the most frequently identified genospecies in PCR-positive questing I. ricinus ticks, followed by B. valaisiana (89% and 11%, respectively). The absence of B. afzelii infection in ticks feeding on passerine birds, despite its strong predominance in local questing nymph populations, indicates that avian hosts are not reservoirs of this genospecies and consequently that the rodent-adapted B. afzelii is negatively selected in ticks feeding on these hosts. These results validate the concept of some avian-associated genospecies within the B. burgdorferi s.l. complex and demonstrate that thrush species may support the circulation of B. garinii and B. valaisiana under natural conditions.     

Variable effects of host characteristics on species richness of flea infracommunities in rodents from three continents

We studied the effect of host gender and body mass on species richness of flea infracommunities in nine rodent host species from three biomes (temperate zone of central Europe, desert of the Middle East and the tropics of East Africa). Using season- and species-specific generalized linear mixed models and controlling for year-to-year variation, spatial clustering of rodent sampling and over-dispersion of the data, we found inconsistent associations between host characteristics and flea species richness. We found strong support for male-biased flea parasitism, especially during the reproductive period (higher species richness in male hosts than in females) in all considered European rodents (Apodemus agrarius, Myodes glareolus and Microtus arvalis) and in one rodent species from the Middle East (Dipodillus dasyurus). In contrast, two of three African rodent species (Lophuromys kilonzoi and Praomys delectorum) demonstrated a trend of female-biased flea species richness. Positive associations between body mass and the number of flea species were detected mainly in males (five of nine species: A. agrarius, M. glareolus, M. arvalis, D. dasyurus and Mastomys natalensis) and not in females (except for M. natalensis). The results of this study support earlier reports that gender-biased, in general, and male-biased, in particular, infestation by ectoparasites is not a universal rule. This suggests that mechanisms of parasite acquisition by an individual host are species-specific and have evolved independently in different rodent host-flea systems.     

Absence of Borrelia spp., Candidatus Neoehrlichia mikurensis, and Anaplasma phagocytophilum in questing adult Dermacentor reticulatus ticks

To determine whether Dermacentor reticulatus ticks are infected by Borrelia spp., Candidatus Neoehrlichia mikurensis, or Anaplasma phagocytophilum, we collected questing adults in the outskirts of Berlin, Germany, examined them for the presence of DNA of these pathogens, and compared the infection rates to those of sympatric Ixodes ricinus ticks. Questing D. reticulatus adults appeared not to harbor the bacterial pathogens that are prevalent in I. ricinus ticks. Based on our sample size, the estimated prevalence of each of these pathogens in D. reticulatus ticks would be well below three tenth of a percent (<0.3 %). For pathogens which so rarely infect D. reticulatus ticks, this tick likely plays no epidemiologic vector role for either their enzootic transmission cycle in nature or their transmission to people.     

Human pathogenic borreliae in Ixodes ricinus ticks in natural and urban ecosystem (Czech Republic)

A total of 1279 field-collected Ixodes ricinus ticks were screened for Borrelia burgdorferi sensu lato (s.l.) in a natural and an urban ecosystem of Ostrava city (Czech Republic) by using molecular methods. Minimal prevalence rate for Borrelia burgdorferi s.l. in ticks for the urban park Bělský les was found to be 13.8% (17.6% in males, 17.8% in females and 11.7% in nymphs), similarly for the natural site Proskovice was minimal prevalence 15% (12.5% in males, 20% in females and 14.9% in nymphs). Six proven human pathogenic genomic species have been recorded in the study: B. afzelii, B. garinii, B. burgdorferi s.s., B. valaisiana, B. lusitaniae, and B. spielmanii. Emerging B. spielmanii was detected for the first time in Ixodes ricinus ticks in the region. Our results highlight the need for surveillance of zoonotic tick-borne pathogens even in urban areas.     

Study of Lyme borreliosis in Ukraine

Cases of human Lyme borreliosis (LB) are registered in all administrative regions of Ukraine and in the Autonomous Republic of Crimea with an increasing tendency. The hard tick Ixodes ricinus was proved as the main vector of Borrelia burgdorferi s.l., the causative agents of LB. We identified active natural LB foci, in which almost 25% of the adult I. ricinus ticks contained borrelias and more than 30% of the human population were seropositive for Lyme borreliae. The role of Mus musculus, Microtus arvalis, Myodes glareolus, Apodemus agrarius, and A. sylvaticus in the transmission cycle of the LB agent(s) was revealed. Combined foci and cases of LB/TBE (tick-borne encephalitis) mixed infection were registered in 8 oblasts. A considerable spectrum of different clinical manifestations of LB has been found including erythema migrans in 64.9% of cases, neurologic symptoms in 26.1%, rheumatic affliction in 24.7%, and cardiovascular problems in 8.3%.     

Lung mites (Pneumocoptes sp.) in bank voles (Clethrionomys glareolus) in Southwest Germany

Lung mites of the genusPneumocoptes were found in bank voles (Clethrionomys glareolus) in Southwest Germany. This is the second time that lung mites have been recorded from a rodent in Europe¹. In 1964 they were discovered in histological sections of a lung of a bank vole in France and were described asP. tiollaisi Doby, 1963. Only three more species of the genus are known from rodents in the United States. The mites are viviparous; larvae and nymphs are described for the first time. The host specificity seems to be “natural” and not “physiological”, since in a natural environment only bank voles were found to be infected. In the laboratory, mites were transmitted from infected bank vole mothers to sucklings of the common field vole (Microtus arvalis).     

Prevalence of Borrelia burgdorferi sensu lato in the selected Ixodes ricinus (Acari: Ixodidae) population in Weilburg forests,Hesse, Germany

We studied the presence of Borrelia burgdorferi sensu lato in Ixodes ricinus ticks collected in woodland areas in the vicinity of Weilburg (Hesse, Germany). Ticks (n = 13347) were collected in five localities in 1996 and were fixed in 70% ethanol. Out of them, 4404 specimens were analysed individually (n = 406) and in 796 pools of 2-10 specimens (n = 3998) by the polymerase chain reaction (PCR). The calculated minimal infection rate of individual and pooled ticks was 0% in larvae (n = 280), 6.9 % in nymphs (n = 3600), 13.9 % in males (n = 280) and 20.9 % in females (n = 244). Prevalence of B. burgdorferi s. 1. in I. ricinus was determined with respect to the abundance and seasonal activity of the ticks.     

<Emphasis Type="Italic">Rickettsia</Emphasis> species in fleas collected from small mammals in Slovakia

Epidemiological and epizootiological studies of Rickettsia felis and other Rickettsia spp. are very important, because their natural cycle has not yet been established completely. In total, 315 fleas (Siphonaptera) of 11 species of Ceratophyllidae, Hystrichopsyllidae and Leptopsyllidae families were tested for the presence of Rickettsia species and Coxiella burnetii with conventional and specific quantitative real-time PCR assays. Fleas were collected from five rodent hosts (Myodes glareolus, Apodemus flavicollis, Apodemus agrarius, Microtus subterraneus, Microtus arvalis) and three shrew species (Sorex araneus, Neomys fodiens, Crocidura suaveolens) captured in Eastern and Southern Slovakia. Overall, Rickettsia spp. was found in 10.8 % (34/315) of the tested fleas of Ctenophthalmus agyrtes, Ctenophthalmus solutus, Ctenophthalmus uncinatus and Nosopsyllus fasciatus species. Infected fleas were coming from A. flavicollis, A. agrarius, and M. glareolus captured in Eastern Slovakia. C. burnetii was not found in any fleas. R. felis, Rickettsia helvetica, unidentified Rickettsia, and rickettsial endosymbionts were identified in fleas infesting small mammals in the Ko?ice region, Eastern Slovakia. This study is the first report of R. felis infection in C. solutus male flea collected from A. agrarius in Slovakia.     

Prevalence of Borrelia burgdorferi sensu lato in the Nightingale (Luscinia megarhynchos) and other passerine birds

In order to explore the involvement of terrestrial birds in the ecology of Lyme disease spirochetes, we determined the presence of Borrelia burgdorferi s. 1. DNA in tick larvae feeding on the hosts. Birds were caught at several study sites along the Rhine valley in SW Germany between August 1999 and March 2001. A total of 987 Ixodes ricinus larvae were collected from 225 birds belonging to 20 host species. The following four passerine species that have not yet been subject to detailed reservoir competence analyses were investigated: Nightingale (Luscinia megarhynchos), Dunnock (Prunella modularis), Chiffchaff (Phylloscopits collybita) and Reed warbler (Acroceph-alus scirpaceus). Borrelia DNA was analysed in attached ticks and for one species, the Nightingale, blood samples were included. Borrelia DNA was amplified by means of the polymerase chain reaction (PCR) targeting the ospA gene of B. burgdorferi s. 1. and 1–2 larvae per bird were analysed. On the basis of one larva per individual bird, Borrelia DNA could be detected in six out of nine larval ticks from the Nightingale, in one out of ten ticks from the Dunnock, in three of nine ticks from the Chiffchaff, and in two out of 21 larval ticks from Reed warblers. Five out of nine ticks removed from Robins Eritbacus rubecula in winter were found to be Borrelia positive. Blood samples of Nightingales caught during the breeding period were ospA-gene-positive in 71 of 138 birds (51 %).     

Borrelia burgdorferi sensu lato genospecies in questing Ixodes ricinus ticks in Austria

Unfed ticks of all instars (Ixodes ricinus, n=853; Haemaphysalis concinna, n=11) collected in all nine federal states of Austria were individually examined for the presence of Borrelia burgdorferi sensu lato (s.l.) using PCR. The mean overall infection rate was 14.4%. Infection rates were 24.5% in adult ticks, 16.1% in nymphs, and 1.6% in larvae. Four genospecies were detected, including B. valaisiana which was detected for the first time in Austria. The most common B. burgdorferi s.l. genospecies was B. garinii (66.9%), followed by B. valaisiana (13.7%), B. afzelii (11.3%), and B. burgdorferi sensu stricto (s.s.) (6.5%). Two specimens (1.6%) could not be identified to the genospecies level. Geographically, the highest infection rates were detected in the federal state of Vorarlberg (33.3%), B. garinii and B. afzelii being the most prevalent genospecies. B. valaisiana occurred most often in the federal state of Lower Austria, and B. burgdorferi s.s. was focally distributed in the Tyrol, in the surroundings of Imst.     

Prevalence of Borrelia burgdorferi s.l. in ticks feeding on humans in Thuringia/Germany

In 2004, a total of 618 Ixodes ricinus ticks fed on humans were collected by physicians throughout Thuringia. The prevalence rates of Borrelia burgdorferi sensu lato (s.l.) genotypes were determined by nested PCR and restriction fragment length polymorphism, targeting a 0.8-kb fragment of the ospA gene. The total prevalence of B. burgdorferi s.l. was 6.1%. B. afzelii was found in 67%, B. valaisiana in 15% and B. garinii in 15% of the positive ticks (3% could not be determined). In one tick, a double infection with B. valaisiana type II and B. garinii OspA type V was detected. Female adult ticks had the highest infection rate (11.7%), followed by nymphs (4.5%) and larvae (3.4%). The overall prevalence increased from spring (4.0%) to autumn (10.0%). Nevertheless, the risk of infection was maximal in summer, because of a much higher infestation and consequently a higher absolute number of infected ticks. The predominance of B. afzelii probably results from its resistance against human serum. The unexpectedly low total prevalence is possibly caused by immune defence mechanisms (e.g. complement) effective against less resistant B. burgdorferi s.l. strains in the tick.     

Identification of<Emphasis Type="Italic"> Borrelia burgdorferi</Emphasis> sensu lato,<Emphasis Type="Italic"> Anaplasma</Emphasis> and<Emphasis Type="Italic"> Ehrlichia</Emphasis> Species,and Spotted Fever Group Rickettsiae in Ticks from Southeastern Europe

Prevalence data for tick-borne pathogens are used to assess the risk for human health. In this study the presence and identity of Borrelia burgdorferi sensu lato, Ehrlichia, Anaplasma, and Rickettsia species in Bulgarian Ixodes ricinus ticks and in non-Ixodes ticks from Turkey and Albania was determined by polymerase chain reaction (PCR) and reverse line blot hybridization. In the adult Bulgarian ticks, the prevalence of Borrelia burgdorferi sensu lato infection was approximately 40%, while Borrelia afzelii was the predominant species, representing more than half of all Borrelia-positive ticks. Ehrlichia and Anaplasma species were detected in 35% of the adult Ixodes ricinus ticks and in 10% of the nymphs. Sequence analysis of PCR products reacting with the Anaplasma phagocytophila probe revealed a 16S rRNA gene identical to that of the Anaplasma phagocytophila prototype strain. Ehrlichia and Anaplasma species were found in approximately 7% of the non-Ixodes ticks. Sequence analysis of some of these samples revealed the presence of Anaplasma ovis, Ehrlichia canis, and a species closely resembling Ehrlichia chaffeensis. About half of all adult ticks examined and approximately 20% of all nymphs were infected with Rickettsia species. In Ixodes ricinus ticks, Rickettsia helvetica and a Rickettsia species designated as IRS3 were found in high prevalence. Rickettsia conorii was found in virtually all non-Ixodes tick species from Albania and Turkey. The results of this study show that many tick-borne diseases are most probably endemic in the Balkan area. Furthermore, the results suggest that there is a considerable chance for simultaneous transmission of tick-borne pathogens to human beings.     

Transmission of the blood parasite Hemolivia mariae between its lizard and tick hosts

The haemogregarine Hemolivia mariae is found in the erythrocytes of a natural population of the lizard Tiliqua rugosa. It infects two tick species, Amblyomma limbatum and Aponomma hydrosauri, which parasitise lizards. In laboratory experiments, engorged Amb. limbatum nymphs from infected lizards transmitted the haemogregarine to uninfected lizards significantly more often than engorged Ap. hydrosauri nymphs. Dissections of larvae and nymphs of both species fed on the same infected hosts showed that Amb. limbatum ticks were significantly more likely to become infected than Ap. hydrosauri ticks. In Amb. limbatum, oval cysts containing parasite stages thought to be infective to the lizard host had developed within 15 days of engorged nymphs detaching from an infected host. The chance of Ap. hydrosauri becoming infected and the intensity of infection in Amb. limbatum increased when ticks were fed on infected hosts as larvae and as nymphs compared with those fed on an infected host only as a nymph. This suggests that infections can accumulate over the tick life stages. Since the two tick species have broadly parapatric distributions, the boundary between the tick species may have implications for the distribution of H. mariae. Received: 12 April 1999 / Accepted: 6 May 1999     

Ein Beitrag zur Biologie von Hepatozoon erhardovae Krampitz 1964 in Rötelmäusen aus der Südweststeiermark und des Neusiedlerseegebietes (Burgenland)

Zusammenfassung Das Vorkommen von Hepatozoon erhardovae in wildgefangenen R?telm?usen (Clethrionomys glareolus) aus Populationen der genannten Gebiete wird untersucht. Dabei werden die Biologie der Schizonten, ihre Verteilung in der Lunge und der Weiterverlauf natürlich erworbener Infektionen bei streng ektoparasitenfreier Haltung der Wirtstiere beobachtet. Auf die Ansammlung von Gametocyten in Larven von Ixodes ricinus und Neotrombicula zachvatkini nach der Blutmahlzeit an stark infizierten R?telm?usen wird hingewiesen. Ferner kann gelegentlich eine Parasit?mie im unspezifischen Zwischenwirt (Apodemus flavicollis) mit Hilfe eines spzifischen übertr?gers (Megabothris turbidus) erzeugt werden.

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Additional observations to the biology of Hepatozoon erhardovae Krampitz 1964 in bank voles from the south-western styria and from areas around the neusiedlersee (Burgenland)

Summary The incidence of Hepatozoon erhardovae in the blood of bank voles (Clethrionomys glareolus) captured in the investigated areas is examined. The biology of schizonts, their distribution in the lobes of the lung and the further development of natural infections in vertebrate hosts kept strictly free of ectoparasites are observed. The accumulation of gametocytes in larvae of the tick Ixodes ricinus and of the mite Neotrombicula zachvatkini after sucking on strongly infected bank voles is pointed out. Occasionally a parasitaemia is produced in the non-specific host (Apodemus flavicollis), but only with a specific transmitter (Megabothris turbidus).

     

Biological control of the tick Ixodes ricinus with entomopathogenic fungi and nematodes: Preliminary results from laboratory experiments

In Central Europe, Lyme disease and tick-borne encephalitis (TBE) are transmitted by the tick Ixodes ricinus. In the last years, the prevalence of TBE virus in I. ricinus and also the number of human TBE infections have increased considerably in south-western Germany. A similar development is presumed for Borrelia burgdorferi s.l. For biocontrol of the vector I. ricinus, several options are presently evaluated. Among potential biocontrol agents, entomopathogenic fungi, nematodes, and parasitic wasps are the most promising candidates. In first laboratory experiments, different strains of the fungi Metarhizium anisopliae (five strains), Beauveria bassiana (three strains), and Paecilomyces fumosoroseus (two strains) were tested by placing I. ricinus larvae (fed and unfed) and nymphs (fed and unfed) in Petri dishes with filter paper soaked with conidial or blastospore suspensions (2.4×10³ to 9.6×10⁶ per cm²). Ticks were exposed to the different fungi for at least 35 days in the dark at temperatures of 21–24 °C. The best LT₅₀ values for unfed larvae (14 days) and unfed nymphs (21 days) were obtained with blastospores of M. anisopliae 97 at 1.4×10⁶ per cm². In order to evaluate the potential of entomopathogenic nematodes, the efficacies of three different species, Steinernema carpocapsae, S. feltiae, and Heterorhabditis bacteriophora, were investigated in the laboratory. I. ricinus nymphs (fed and unfed) and unfed females were placed in Petri dishes containing a wet filter paper with 300 and 600 infective nematode larvae per cm². Ticks were exposed to the nematodes for at least 15 days in the dark at an average temperature of 25 °C. The highest mortality was observed in unfed female ticks treated with S. carpocapsae. Results show that among the fungi tested the most promising control efficacy was obtained with two isolates of M. anisopliae, whereas S. carpocapsae was most successful among the nematodes tested against I. ricinus.     

Factors affecting patterns of tick parasitism on forest rodents in tick-borne encephalitis risk areas,Germany

Identifying factors affecting individual vector burdens is essential for understanding infectious disease systems. Drawing upon data of a rodent monitoring programme conducted in nine different forest patches in southern Hesse, Germany, we developed models which predict tick (Ixodes spp. and Dermacentor spp.) burdens on two rodent species Apodemus flavicollis and Myodes glareolus. Models for the two rodent species were broadly similar but differed in some aspects. Patterns of Ixodes spp. burdens were influenced by extrinsic factors such as season, unexplained spatial variation (both species), relative humidity and vegetation cover (A. flavicollis). We found support for the ‘body mass’ (tick burdens increase with body mass/age) and for the ‘dilution’ hypothesis (tick burdens decline with increasing rodent densities) and little support for the ‘sex-bias’ hypothesis (both species). Surprisingly, roe deer densities were not correlated with larvae counts on rodents. Factors influencing the mean burden did not significantly explain the observed dispersion of tick counts. Co-feeding aggregations, which are essential for tick-borne disease transmission, were mainly found in A. flavicollis of high body mass trapped in areas with fast increase in spring temperatures. Locally, Dermacentor spp. appears to be an important parasite on A. flavicollis and M. glareolus. Dermacentor spp. was rather confined to areas with higher average temperatures during the vegetation period. Nymphs of Dermacentor spp. mainly fed on M. glareolus and were seldom found on A. flavicollis. Whereas Ixodes spp. is the dominant tick genus in woodlands of our study area, the distribution and epidemiological role of Dermacentor spp. should be monitored closely.     

Prevalence of Borrelia burgdorferi sensu lato in Ixodes ricinus and I. lividus ticks collected from wild birds in the Republic of Moldova

Wild birds are important reservoirs of Borrelia burgdorferi sensu lato, the bacterial species complex comprising the agents of Lyme disease in North America and Eurasia. We studied the prevalence of B. burgdorferi s.l. in Ixodes ricinus and I. lividus ticks collected from wild birds in the Republic of Moldova. Wild birds were captured in Kodri forest reserve and in biocenoses near the Dnestr River bank and examined for infestation with ticks. A total of 123 I. ricinus and 54 I. lividus ticks were analyzed for Borrelia spp. B. burgdorferi s.l. was detected in 14% of I. ricinus and 5.5% of I. lividus. Borreliae were most prevalent in I. ricinus ticks collected from blackbirds (17%). BLAST analysis of sequenced PCR products confirmed that I. lividus was infected with both B. burgdorferi s.s. and B. garinii and that I. ricinus was infected with B. burgdorferi s.s. only. This is the first record of the Lyme disease agent in I. lividus ticks.     

Lyme disease in California: interrelationship of ixodid ticks (Acari), rodents, and Borrelia burgdorferi

The association of immature ixodid ticks, several species of rodents, and the Lyme disease spirochete, Borrelia burgdorferi Johnson, Schmid, Hyde, Steigerwalt & Brenner, was studied in two habitats in northern California in spring and summer 1985 and year-round in 1986. A total of 428 rodents were collected from ecotonal chaparral and a woodland-grass-rock outcrop; the former habitat yielded six species, the latter three species. The deer mouse, Peromyscus maniculatus (Wagner), and the pi?on mouse, P. truei (Shufeldt), were the dominant species year-round and collectively comprised 78% of rodents captured within chaparral and 87% from the rock outcrop in 1986. In both habitats, rodents were trapped most frequently in winter and spring, and least often in summer and fall. A total of 306 rodent blood films from all six species were assayed for spirochetes by direct immunofluorescence; of these, only one film prepared from P. truei (n = 123 films from 53 individual mice) was found to contain spirochetes. Immature western black-legged ticks, Ixodes pacificus Cooley & Kohls, and Pacific Coast ticks, Dermacentor occidentalis Marx, were collected from each species of rodent. Larvae of I. pacificus infested P. maniculatus and P. truei in low numbers year-round, but nymphs of this tick rarely parasitized these rodents. D. occidentalis larvae infested P. maniculatus and P. truei in spring and particularly in summer; nymphal ticks infested these mice primarily in summer. The efficiency of visual inspection for collecting immatures of these ticks from P. maniculatus ranged from 45 to 69% in spring and summer, whereas the efficiency of a drop-off technique appeared to be 100%. Spirochetes were detected in <1% of D. occidentalis larvae (n = 310) and nymphs (n = 120), and in approximately 4% of I. pacificus larvae (n = 75) derived from these hosts. The potential significance od these findings in the enzootiology of B. burgdorferi is discussed.     

Wild ruminants in the area of the North-Western Poland as potential reservoir hosts of <Emphasis Type="Italic">Bartonella schoenbuchensis</Emphasis> and <Emphasis Type="Italic">B. bovis</Emphasis>

The aim of this work was to examine if the game species from the north-western Poland, roe deer (Capreolus capreolus), red deer (Cervus elaphus) and wild boar (Sus scrofa), may be reservoir hosts of bacteria from the genus Bartonella, and whether the sheep tick (Ixodes ricinus) is their vector. To this end, the prevalence of Bartonella DNA in the tissues of these game species was measured, just as in sheep ticks (I. ricinus) infesting them, and ticks collected from plants in the hunting area. The prevalence of Bartonella DNA was 39% (23/59) in roe deer and 35% (7/20) in red deer. No Bartonella DNA was detected in any of the 21 wild boars. The presence of Bartonella DNAwas detected in 1.9% of ticks infesting roe deer (2/103), while no pathogen DNA was found in the 20 ticks infesting the red deer and the 3 ticks infesting wild boars, or the 200 ticks collected from plants. Amplicons of two different lengths were obtained; 198 bp, characteristic for B. bovis, and 317 bp, characteristic for B. schoenbuchensis, which were confirmed later by sequencing. The examined ruminants are probably the reservoir hosts of B. schoenbuchensis and B. bovis in the biotope of the Puszcza Wkrzańska Forest, and wild boars do not participate in the Bartonella propagation in the environment. I. ricinus is unlikely to be the main vector of Bartonella species detected in the examined roe deer and red deer; probably other bloodsucking arthropods, parasitizing wild ruminants, play this role.