| 1. |
- Bergström, Sven, et al.
(författare)
-
Molecular characterization of Borrelia burgdorferi isolated from Ixodes ricinus in northern Sweden.
- 1992
-
Ingår i: Scandinavian Journal of Infectious Diseases. - : Informa UK Limited. - 0036-5548 .- 1651-1980. ; 24:2, s. 181-188
-
Tidskriftsartikel (refereegranskat)abstract
- Ixodes ricinus ticks, harbouring Borrelia burgdorferi, were found in an area in northern Sweden, not thought to be endemic for Lyme borreliosis. This investigation took place at Norrbyskär, an island situated in the Bothnian Gulf, 63 degrees 33'N/19 degrees 52'E. One of 42 nymphal and 8/43 adult I. ricinus ticks collected carried spirochetes as seen by phase contrast microscopy. Pure bacterial cultures were obtained from 2 of the ticks. Western blot analysis using species-specific monoclonal antibodies showed that the isolated spirochetes were B. burgdorferi. The identity of the isolated spirochetes was confirmed by DNA amplification using B. burgdorferi OspA and flagellin gene specific oligonucleotides as well as partial DNA sequencing of the respective OspA and flagellin genes. The 2 isolated spirochaete populations were different as shown by their protein profiles in sodium dodecyl sulphate polyacrylamide gels. Moreover, the demonstration of Lyme borreliosis in a patient from the island of Norrbyskär indicates the need for clinical consideration of this disease in northern Sweden.
|
|
| 2. |
- Comstedt, Pär, et al.
(författare)
-
Migratory passerine birds as reservoirs of Lyme borreliosis in Europe.
- 2006
-
Ingår i: Emerging Infectious Diseases. - 1080-6040. ; 12, s. 1087-1095
-
Tidskriftsartikel (refereegranskat)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.
|
|
| 3. |
- Elfving, Karin, et al.
(författare)
-
Dissemination of Spotted Fever Rickettsia Agents in Europe by Migrating Birds
- 2010
-
Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 5:1
-
Tidskriftsartikel (refereegranskat)abstract
- Migratory birds are known to play a role as long-distance vectors for many microorganisms. To investigate whether this is true of rickettsial agents as well, we characterized tick infestation and gathered ticks from 13,260 migratory passerine birds in Sweden. A total of 1127 Ixodes spp. ticks were removed from these birds and the extracted DNA from 957 of them was available for analyses. The DNA was assayed for detection of Rickettsia spp. using real-time PCR, followed by DNA sequencing for species identification. Rickettsia spp. organisms were detected in 108 (11.3%) of the ticks. Rickettsia helvetica, a spotted fever rickettsia associated with human infections, was predominant among the PCR-positive samples. In 9 (0.8%) of the ticks, the partial sequences of 17kDa and ompB genes showed the greatest similarity to Rickettsia monacensis, an etiologic agent of Mediterranean spotted fever-like illness, previously described in southern Europe as well as to the Rickettsia sp. IrITA3 strain. For 15 (1.4%) of the ticks, the 17kDa, ompB, gltA and ompA genes showed the greatest similarity to Rickettsia sp. strain Davousti, Rickettsia japonica and Rickettsia heilongjiangensis, all closely phylogenetically related, the former previously found in Amblyomma tholloni ticks in Africa and previously not detected in Ixodes spp. ticks. The infestation prevalence of ticks infected with rickettsial organisms was four times higher among ground foraging birds than among other bird species, but the two groups were equally competent in transmitting Rickettsia species. The birds did not seem to serve as reservoir hosts for Rickettsia spp., but in one case it seems likely that the bird was rickettsiemic and that the ticks had acquired the bacteria from the blood of the bird. In conclusion, migratory passerine birds host epidemiologically important vector ticks and Rickettsia species and contribute to the geographic distribution of spotted fever rickettsial agents and their diseases.
|
|
| 4. |
- Gustafson, Rolf, et al.
(författare)
-
Prevalence of Borrelia burgdorferi sensu lato infection in Ixodes ricinus in Sweden
- 1995
-
Ingår i: Scandinavian Journal of Infectious Diseases. - : Informa UK Limited. - 0036-5548 .- 1651-1980. ; 27:6, s. 597-601
-
Tidskriftsartikel (refereegranskat)abstract
- Between 1988-1991, a total of 3,141 Ixodes ricinus ticks, 2,740 adults and 401 nymphs, was collected from different localities in 23 of the 25 provinces of Sweden. The ticks were identified, dissected and examined for the presence of Borrelia spirochetes. Indirect immunofluorescence was performed, using an antiserum obtained from rabbits, immunized with sonicated, whole Borrelia burgdorferi spirochetes isolated from Swedish Ixodes ricinus ticks. Borrelia-positive I. ricinus were found in all 23 provinces. The prevalence of infection in adults ranged from 3% in Jämtland to 23% in Södermanland. In nymphs, the infection prevalence ranged from 0% in 9 provinces to 15% in Södermanland. A significantly greater proportion of the adult ticks were found to be positive for Borrelia in the southern and central parts of Sweden as compared to the northern part (Norrland). No significant difference in prevalence could be demonstrated between the western and eastern parts of Sweden. On average, 10% of the nymphs and 15% of the adult I. ricinus were positive for Borrelia. Of 41 non-I. ricinus ticks, none was positive for Borrelia. This study shows that Borrelia burgdorferi sensu lato is present throughout the distributional area of I. ricinus in Sweden. This should lead to increased awareness of signs and symptoms compatible with Lyme borreliosis in persons living in or visiting areas where I. ricinus is present.
|
|
| 5. |
- Jaenson, Thomas G.T. 1948-, et al.
(författare)
-
Risk indicators for the tick Ixodes ricinus and Borrelia burgdorferi sensu lato in Sweden
- 2009
-
Ingår i: Medical and Veterinary Entomology. - : Blackwell. - 0269-283X .- 1365-2915. ; 23:3, s. 226-237
-
Tidskriftsartikel (refereegranskat)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.
|
|
| 6. |
- Kondorosy, Elod, et al.
(författare)
-
Taxonomic corrections to species of Rhyparochromidae (Hemiptera: Heteroptera) described by Carl Peter Thunberg
- 2014
-
Ingår i: Zootaxa. - 1175-5326 .- 1175-5334. ; 3838:5, s. 567-574
-
Tidskriftsartikel (refereegranskat)abstract
- Types of Rhyparochromidae (Hemiptera: Heteroptera: Lygaeoidea) species described by Carl Peter Thunberg, deposited in the Museum of Evolution (formerly Zoologiska Institut), Uppsala University, Uppsala, Sweden, were reexamined and the taxonomic and nomenclatural problems that existed among those species discussed and resolved as required. Lecto-types are designated for Cimex caffer Thunberg, 1784, Lygaeus ater Thunberg, 1822, Lygaeus biguttatus Thunberg, 1822, and Pendulinus guttatus Thunberg, 1825. The lectotype of Pendulinus (now Metochus) guttatus is designated as neotype of Pendulinus (now Metochus) uniguttatus Thunberg, 1822; as a result the former name becomes junior objective synonym of the latter. The following taxonomic changes are proposed: Lethaeus ater (Thunberg, 1822), new combination (from Lygaeus); Migdilybs biguttatus (Thunberg, 1822), new combination (from Lygaeus) = Migdilybs furcifer Hesse, 1925, new subjective synonym; Metochus uniguttatus (Thunberg, 1822) = Metochus bengalensis (Dallas, 1852), confirmed subjective synonym = Metochus yeh (Dohrn, 1860), confirmed subjective synonym; Raglius alboacuminatus (Goeze, 1778) = Cimex caffer Thunberg, 1874, confirmed subjective synonym. Lethaeus barberi Slater, 1964 does not belong to Lethaeus Dallas, 1852 but currently it cannot be placed with confidence in any existing genus.
|
|
| 7. |
- Martel, Carlos, et al.
(författare)
-
Specialization for tachinid fly pollination in the phenologically divergent varieties of the orchid Neotinea ustulata
- 2021
-
Ingår i: Frontiers in Ecology and Evolution. - : Frontiers Media S.A.. - 2296-701X. ; 9
-
Tidskriftsartikel (refereegranskat)abstract
- Despite increased focus on elucidating the various reproductive strategies employed by orchids, we still have only a rather limited understanding of deceptive pollination systems that are not bee- or wasp-mediated. In Europe, the orchid Neotinea ustulata has been known to consist of two phenologically divergent varieties, neither of which provide rewards to its pollinators. However, detailed studies of their reproductive biology have been lacking. Our study aimed to characterize and understand the floral traits (i.e., morphology, color, and scent chemistry) and reproductive biology of N. ustulata. We found that the two varieties differ in all their floral traits; furthermore, while Neotinea ustulata var. ustulata appears to be pollinated by both bees (e.g., Anthophora, Bombus) and flies (e.g., Dilophus, Tachina), var. aestivalis is pollinated almost entirely by flies (i.e., Nowickia, Tachina). Tachinids were also found to be much more effective than bees in removing pollinaria, and we show experimentally that they use the characteristic dark inflorescence top as a cue for approaching inflorescences. Our results thus suggest that while both N. ustulata varieties rely on tachinids for pollination, they differ in their degree of specialization. Further studies are, however, needed to fully understand the reproductive strategy of N. ustulata varieties.
|
|
| 8. |
|
|
| 9. |
- Mejlon, Hans
(författare)
-
Diel activity of Ixodes ricinus Acari: Ixodidæ at two locations near Stockholm, Sweden
- 1997
-
Ingår i: Experimental and Applied Acarology. - 0168-8162. ; 21:4, s. 247-255
-
Tidskriftsartikel (refereegranskat)abstract
- The diel 'activity', i.e. availability, of Ixodes ricinus larvae, nymphs and adults was investigated in a meadow and a forest habitat near Stockholm during 1991-1993. Generally, the immature ticks were more prevalent in the forest than in the meadow. In the meadow, the mean larval and adult numbers varied significantly between 4 h time intervals with the peak activity from 2300 to 0300 h. In the forest, tick numbers did not differ significantly between time intervals. The association of tick activity with certain meteorological variables was strongest in the meadow, where the mean numbers of all tick stages were negatively correlated with temperature.The relative humidity was positively correlated only with the mean numbers of larvae. In contrast, the larval activity in the forest was positively and negatively correlated with temperature and relative humidity, respectively, while the nymphal and adult activity showed no association with these climatic variables. The impact of host activity on tick diel activity is also discussed.
|
|
| 10. |
- Mejlon, Hans
(författare)
-
Host-seeking activity of Ixodes ricinus in relation to the epidemiology of Lyme borreliosis in Sweden
- 2000
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis examines seasonal, diel and vertical distribution patterns of activity of host-seeking Ixodes ricinus (L.) ticks at three localities in south-central Sweden. In addition, by examining the prevalence of infection in ticks with Lyme borreliosis (LB) spirochetes, Borrelia burgdorferi s.l, information for estimating relative LB risk in humans and the effect of control measures directed against this tick vector is provided.The seasonal activity pattern of I. ricinus was, in general, bimodal with peaks of activity in May-June and August-September. Tick densities were generally high at Torö and low at Kungshamn-Morga. The greatest variation in tick density occurred at the sample site level, which indicated a patchy distribution of ticks. The diel activity of adult I. ricinus sampled at Bogesund showed a distinct nocturnal activity peak while nymphal ticks exhibited no particular diel variation. At the meadow site, there was a strong negative association between activity of each tick stage and ambient air temperature, and larval ticks also showed a nocturnal activity peak. I. ricinus of all stages were present in the vegetation up to at least 140 cm above ground level. At Torö, host-seeking larvae were found at significantly lower levels (below 20 cm) in the vegetation compared to nymphs and adults (50-59 and 60-79 cm, respectively). Vegetation structure is likely to be the main factor governing tick vertical distribution at this locality. The northern limit of the geographical distribution of I. ricinus in Sweden corresponds with the southern boundary of the taiga zone, as well as with several other climatic or vegetational isoclines primarily associated with the vegetation period.The prevalence rates of Borrelia spirochetes, recorded by phase-contrast microscopy in host-seeking I. ricinus, were 0% in larvae, 5.8-13.1% in nymphs and 14.5-28.6% in adult ticks. The human LB risk, estimated by the number of Borrelia-infected nymphs per hectare, was greater at Torö than at Kungshamn-Morga and greater in woodland than in open areas. The risk also possessed a bimodal seasonal pattern similar to that of subadult host-seeking activity. Controlling the number of infected nymphs through de-ticking of reservoir hosts seems not to be an effective control measure in Sweden due to the ubiquitous availability of alternative reservoir hosts.
|
|
