Blood-sucking arthropods, collected in South Moravia, Czech Republic, were examined by darkfteld microscopy for borreliae from 1988 to 1996. Among host-seeking ixodid ticks (8481 Ixodes ricinus (L.), 372 Dermacentor reticulatus (Fabr.), 167 Haemaphysalis concinna Koch), borreliae were only observed in adult (23.2%), nymphal (17.2%) and larval (6.3%) I. ricinus. The prevalence of borreliae in I. ricinus did not vary considerably among habitats except for lower values in agroecosystems, xerothermic oak woods and grasslands. The frequency of intensity of spirochaetal infection (log,,, counts of borreliae per tick) in /. ricinus approximated the negative binomial distribution. The proportions of host-seeking female and nymphal ticks containing >100 borreliae were 5.0% and 1.7%, respectively. Among preimaginal ticks (749 I. ricinus, 222 D. reticulatus, 82 II. concinna) parasitizing free-living forest birds and small mammals, borreliae were detected in 6.1% of larval and 10.3% of nymphal I. ricinus, and in one larval H. concinna', 3.2% of the birds and 19.4% of the mammals carried infected ticks. Among 3464 female mosquitoes (Culicidae) of 6 species, 4.1% contained spirochaetes: 1.4% of Aedes vexans Meig., 1.3% of A. cantons (Meig.), 2.2% of A. sticticus (Meig.), 2.2% of Culex pipiens pipiens L. and 5.9% of C. p. molestus Forskal. Borreliae were also detected in 8.4% of 142 fleas (Siphonaptera, largely Ctenophthalmus agyrtes Heller and Hystrichopsylla talpae Curtis) collected from small mammals. Twelve isolates of B. burgdorferi sensu lato have been identified to genospecies: 6 strains from I. ricinus (4 Borrelia garinii Baranton et al., 1 В. afzelii Canica et al. and 1 В. lusitaniae Le Fleche et al.), 1 strain from A. vexans (В. afze-lii), 2 strains from C. agyrtes (В. afzelii), and 3 strains from host rodents (B. afzelii).
A comparison of the behavioural peculiarities of Ixodes persulcatus Schulze, 1930 (north-western population, Russia) and Ixodes ricinus (L., 1758) from western Russia and Denmark was determined by using two methods. Method 1 involved a sojourn of ticks on vertical plastic slicks and showed that the questing behaviour of /. ricinus nymphs was dependent on temperature and relative humidity (RH). A significantly greater number of nymphs quested at 22°C and 100% RH than at 18°C. When the humidity was reduced to 30% all of the nymphs departed. In the second method, the activity of licks on an inclined “ticksdromc” was estimated. The activity of I. ricinus adults from the Danish population was 1.2 times greater than that of ticks from Russia. Females of the species studied and specimens from all study areas were more active than all other stages of development. The locomotor activity of both adult and immature I. ricinus that were infected with Borrelia burgdorferi sensu lato was suppressed when compared with uninfected specimens. The locomotor activity of I. persulcatus females infected by borreliae with exoskeleton anomalies was 1.3 times greater (PO.05) than that of infected ticks without anomalies. Our data showed that infected females with exoskeleton anomalies could crawl faster on a human and reach uncovered parts of the body that are vulnerable for attachment and feeding. A study of locomotor aclivity and questing behaviour may be useful for comparing the risk for different tick species and populations to transmit tick-borne pathogens.
A total of 7210 unfed adult Ixodes persulcatus Schulze, 1930 and I. ricinus (L., 1758) ticks were collected from the vegetation by flagging in 35 study sites located in the zone of their sympatry (mainly in Leningrad region, Russia). Borrelia infection in ticks was estimated by the dark-field microscopic analysis of gut contents in standard vital preparations at a magnification of ×600. No correlation was revealed between the series of parameters characterising the abundance of each tick species (τ = -0.13) and between the series of these parameters and the prevalence of Borrelia in each vector. It is concluded that in the broad zone of I. persulcatus and I. ricinus sympatry, the presence and proportion of one vector in the ecosystem does not have any significant effect on the extensity of infection and on the epizootic and epidemic significance of the other vector. Each tick species has its independent (of the other species) and relatively original functional role in the focal ecosystem.