Investigation of haematophagous arthropods for borreliae--summarized data, 1988-1996.

Blood-sucking arthropods, collected in South Moravia, Czech Republic, were examined by darkfield 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 (log10 counts of borreliae per tick) in I. 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 H. 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. cantans (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 B. afzelii Canica et al. and 1 B. lusitaniae Le Fleche et al.), 1 strain from A. vexans (B. afzelii), 2 strains from C. agyrtes (B. afzelii), and 3 strains from host rodents (B. afzelii).