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

Creator:
Hubálek, Zdeněk, Halouzka, Jiří, and Juřicová, Zina
Format:
print
Type:
model:internalpart and TEXT
Subject:
Borrelia, Lyme borreliosis, Ixodes, Dermacentor, Haemaphysalis, Aedes, Culex, Ctenophthalmus, birds, and mammals
Language:
English
Description:
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).
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

4. Variation in parameters affecting risk of human disease due to TBE virus

Creator:
Korenberg, E. I. and Kovalevskii, Yu V.
Format:
print
Type:
model:internalpart and TEXT
Subject:
tick-borne encephalitis, Ixodes persulcatus, and risk of infection
Language:
English
Description:
To rank variables affecting risk of human disease due to tick-borne encephalitis (TBE) virus in the Russian Far East, we compared annual changes in ( 1 ) frequency of human contact with vector ticks, (2) prevalence of infection in the tick population and (3) quantity of virus present infected ticks. Sites were sampled uniformly over a 4-year period in a forested region where Ixodes persulcatus serves as the principle vector. The questing density of ticks on vegetation remained relatively constant during the course of this study. The frequency of contacts of the local human population with ticks carrying different doses of the TBE virus was changeable. The rate of TBE infection of humans in the study site corresponded to that of human contacts with highly infected ticks. The density of highly infected ticks represents the principal parameter for determining potential epidemiological significance of a natural TBE focus.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public