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- Comstedt, Pär, et al.
(author)
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Migratory passerine birds as reservoirs of Lyme borreliosis in Europe.
- 2006
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In: Emerging Infectious Diseases. - 1080-6040. ; 12, s. 1087-1095
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Journal article (peer-reviewed)abstract
- To define the role of birds as reservoirs and disseminators of Borrelia spirochetes, we characterized tick infestation and reservoir competence of migratory passerine birds in Sweden. A total of 1,120 immature Ixodes ricinus ticks were removed from 13,260 birds and assayed by quantitative polymerase chain reaction (PCR) for Borrelia, followed by DNA sequencing for species and genotype identification. Distributions of ticks on birds were aggregated, presumably because of varying encounters with ticks along migratory routes. Lyme borreliosis spirochetes were detected in 160 (1.4%) ticks. Borrelia garinii was the most common species in PCR-positive samples and included genotypes associated with human infections. Infestation prevalence with infected ticks was 5 times greater among ground-foraging birds than other bird species, but the 2 groups were equally competent in transmitting Borrelia. Migratory passerine birds host epidemiologically important vector ticks and Borrelia species and vary in effectiveness as reservoirs on the basis of their feeding behavior.
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| 2. |
- Jaenson, Thomas G.T. 1948-, et al.
(author)
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Risk indicators for the tick Ixodes ricinus and Borrelia burgdorferi sensu lato in Sweden
- 2009
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In: Medical and Veterinary Entomology. - : Blackwell. - 0269-283X .- 1365-2915. ; 23:3, s. 226-237
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Journal article (peer-reviewed)abstract
- The distributional area of the tick Ixodes ricinus (L.), the primary European vector to humans of Lyme borreliosis spirochaetes (Borrelia burgdorferi sensu lato) and tick-borne encephalitis virus, appears to be increasing in Sweden. It is therefore important to determine which environmental factors are most useful to assess risk of human exposure to this tick and its associated pathogens. The geographical distribution of I. ricinus in Sweden was analyzed with respect to vegetation zones and climate. The northern limit of I. ricinus and B. burgdorferi s.l. in Sweden corresponds roughly to the northern limit of the southern boreal vegetation zone, and is characterized climatically by a mean duration of 150 days with snow cover and a vegetation period averaging 170 days. The zoogeographical distribution of I. ricinus in Sweden can be classified as southerly-central, with the center of the distribution south Limes Norrlandicus. Ixodes ricinus nymphs from 13 localities in different parts of Sweden were examined for presence of B. burgdorferi s.l. and found to be infected with B. afzelii and B. garinii. Tick sampling localities were characterized on the basis of density of Borrelia-infected I. ricinus nymphs, presence of specific mammals, dominant vegetation and climate. Densities of I. ricinus nymphs and Borrelia-infected nymphs were significantly correlated, and nymphal density can thus serve as a general indicator of risk for exposure to Lyme borreliosis spirochaetes. Analysis of data from this and other studies suggest that high densities of Borrelia-infected nymphs typically occur in coastal, broad-leaf vegetation and in mixed deciduous/spruce vegetation in southern Sweden. Ixodes ricinus populations consistently infected with B. burgdorferi s.l. can occur in biotopes with (i) shrews, rodents, hares and birds, (ii) shrews, rodents, hares, deer and birds, (iii) and on islands where the varying hare (Lepus timidus) is the only mammalian tick host.
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| 3. |
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| 4. |
- Waldenström, Jonas, et al.
(author)
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Migrating birds and tickborne encephalitis virus
- 2007
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In: Emerging Infectious Diseases. - : Centers for Disease Control and Prevention (CDC). - 1080-6040 .- 1080-6059. ; 13:8, s. 1215-8
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Journal article (peer-reviewed)abstract
- During spring and autumn 2001, we screened 13,260 migrating birds at Ottenby Bird Observatory, Sweden, and found 3.4% were infested with ticks. Four birds, each a different passerine species, carried tickborne encephalitis virus (TBEV)-infected ticks (Ixodes ricinus). Migrating birds may play a role in the geographic dispersal of TBEV-infected ticks.
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