| 1. |
- Ahola, T, et al.
(författare)
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Therapeutics and vaccines against chikungunya virus
- 2015
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Ingår i: Vector borne and zoonotic diseases (Larchmont, N.Y.). - : Mary Ann Liebert Inc. - 1557-7759 .- 1530-3667. ; 15:4, s. 250-257
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Tidskriftsartikel (refereegranskat)
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| 2. |
- Andersson, Martin, et al.
(författare)
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Co-Infection with 'Candidatus Neoehrlichia mikurensis' and Borrelia afzelii in Ixodes ricinus Ticks in Southern Sweden.
- 2013
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Ingår i: Vector Borne and Zoonotic Diseases. - : Mary Ann Liebert Inc. - 1557-7759 .- 1530-3667. ; 13:7, s. 438-442
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Tidskriftsartikel (refereegranskat)abstract
- Abstract The tick-borne bacterium 'Candidatus Neoehrlichia mikurensis' has recently been recognized as a human pathogen in Europe and appears to be the second most common pathogenic bacterium in Ixodes ricinus ticks in central Europe, second to Borrelia afzelii. Here, we investigate the prevalence of 'Candidatus N. mikurensis' in host-seeking ticks in southern Sweden and the rate of co-infection with B. afzelii. We developed a real-time qPCR assay targeting the groEL gene of 'Candidatus N. mikurensis' and applied this assay to 949 I. ricinus ticks collected at several locations over 2 years. We found an overall prevalence of 6.0%, which means that Candidatus N. mikurensis is one of the most common tick-transmitted zoonotic agents in this area. Co-infections with both 'Candidatus N. mikurensis' and B. afzelii occurred in 2.1% of the ticks, which is significantly more than expected under random co-occurrence. The infection intensity (number of bacterial cells) of 'Candidatus N. mikurensis' was not affected by co-infection with B. afzelii, and vice versa. We conclude that there is a risk for simultaneous transmission of these 2 tick-borne pathogens. The potential medical consequences of this require further investigation.
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| 3. |
- Bennet, Louise, et al.
(författare)
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Effect of Gender on Clinical and Epidemiologic Features of Lyme Borreliosis
- 2007
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Ingår i: Vector Borne and Zoonotic Diseases. - : Vector-borne and zoonotic diseases. - 1530-3667 .- 1557-7759. ; 7:1, s. 34-41
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Tidskriftsartikel (refereegranskat)abstract
- The aim is to highlight the influence of patients’ gender on Lyme borreliosis and especially erythema migrans (EM), focusing on exposure to tick bites, epidemiology, and the clinical picture. All studies were conducted in the county of Blekinge, located in southeastern Sweden. A prospective study was conducted in 235 individuals (women, n=110; men, n=125) engaged in recreational or occupational activities focusing on exposure to tick bites. A retrospective epidemiological study evaluating 123,495 electronic patients´ records (women, n=61,712; men, n=61,783) and a prospective clinical study including 118 patients (women, n=54; men, n=64) 18 years or older seeking care for EM > 5 cm in diameter with genospecies verified by polymerase chain reaction were conducted. Results: Women 40 years or older had a 48% higher risk than men 40 years or older and 42% higher risk than women younger than 40 years of attracting tick bites (0.0188 versus 0.0127 and 0.0188 versus 0.0132 tick bites respectively per hour). Additionally they had a 96% higher risk than men younger than 40 years of attracting tick bites (0.0188 versus 0.0096). The annual incidence rate of EM in women was 506 and in men 423 cases per 100,000 inhabitants (p<0.001). Significant differences in incidence rates occurred in those 40 years or older. Odds ratios for males infected with Borrelia afzelii developing nonannular EM were 0.09 (95% confidence interval [CI] 0.03 to 0.33) in comparison with females infected by Borrelia afzelii. Conclusions: Significant gender differences in the risk of contracting tick bites, incidence rates, and clinical picture of EM have been observed. Exposure to tick bites alone may not explain these observations and further studies need to be done to clarify the biologic, immunologic, and sociological mechanisms causing these differences.
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| 4. |
- Bergqvist, Joakim, et al.
(författare)
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Detection and Isolation of Sindbis Virus from Mosquitoes Captured During an Outbreak in Sweden, 2013
- 2015
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Ingår i: Vector Borne and Zoonotic Diseases. - : Mary Ann Liebert Inc. - 1530-3667 .- 1557-7759. ; 15:2, s. 133-140
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Tidskriftsartikel (refereegranskat)abstract
- Mosquito-borne alphaviruses have the potential to cause large outbreaks throughout the world. Here we investigated the causative agent of an unexpected Sindbis virus (SINV) outbreak during August-September, 2013, in a previously nonendemic region of Sweden. Mosquitoes were collected using carbon dioxide-baited CDC traps at locations close to human cases. The mosquitoes were initially screened as large pools by SINV-specific quantitative RT-PCR, and the SINV-positive mosquitoes were species determined by single-nucleotide polymorphism (SNP) analysis, followed by sequencing the barcoding region of the cytochrome oxidase I gene. The proportion of the collected mosquitoes was determined by a metabarcoding strategy. By using novel strategies for PCR screening and genetic typing, a new SINV strain, Lovanger, was isolated from a pool of 1600 mosquitoes composed of Culex, Culiseta, and Aedes mosquitoes as determined by metabarcoding. The SINV-positive mosquito Culiseta morsitans was identified by SNP analysis and sequencing. After whole-genome sequencing and phylogenetic analysis, the SINV Lovanger isolate was shown to be most closely similar to recent Finnish SINV isolates. In conclusion, within a few weeks, we were able to detect and isolate a novel SINV strain and identify the mosquito vector during a sudden SINV outbreak.
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| 5. |
- Brissette, Catherine, et al.
(författare)
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An Expert Panel DiscussionLyme Disease in Europe
- 2023
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Ingår i: Vector Borne and Zoonotic Diseases. - : MARY ANN LIEBERT, INC. - 1530-3667 .- 1557-7759. ; 23:S1
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 6. |
- Ecke, Frauke, et al.
(författare)
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Geographical Distribution of Ljungan Virus in Small Mammals in Europe
- 2020
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Ingår i: Vector-Borne and Zoonotic Diseases. - : Mary Ann Liebert Inc. - 1530-3667 .- 1557-7759. ; 20, s. 692-702
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Tidskriftsartikel (refereegranskat)abstract
- Ljungan virus (LV), which belongs to the Parechovirus genus in the Picornaviridae family, was first isolated from bank voles (Myodes glareolus) in Sweden in 1998 and proposed as a zoonotic agent. To improve knowledge of the host association and geographical distribution of LV, tissues from 1685 animals belonging to multiple rodent and insectivore species from 12 European countries were screened for LV-RNA using reverse transcriptase (RT)-PCR. In addition, we investigated how the prevalence of LV-RNA in bank voles is associated with various intrinsic and extrinsic factors. We show that LV is widespread geographically, having been detected in at least one host species in nine European countries. Twelve out of 21 species screened were LV-RNA PCR positive, including, for the first time, the red vole (Myodes rutilus) and the root or tundra vole (Alexandromys formerly Microtus oeconomus), as well as in insectivores, including the bicolored white-toothed shrew (Crocidura leucodon) and the Valais shrew (Sorex antinorii). Results indicated that bank voles are the main rodent host for this virus (overall RT-PCR prevalence: 15.2%). Linear modeling of intrinsic and extrinsic factors that could impact LV prevalence showed a concave-down relationship between body mass and LV occurrence, so that subadults had the highest LV positivity, but LV in older animals was less prevalent. Also, LV prevalence was higher in autumn and lower in spring, and the amount of precipitation recorded during the 6 months preceding the trapping date was negatively correlated with the presence of the virus. Phylogenetic analysis on the 185 base pair species-specific sequence of the 5 ' untranslated region identified high genetic diversity (46.5%) between 80 haplotypes, although no geographical or host-specific patterns of diversity were detected.
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| 7. |
- Ecke, Frauke, et al.
(författare)
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Puumala Orthohantavirus Infection Does Not Affect the Trapping Success of Its Reservoir Host
- 2022
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Ingår i: Vector Borne and Zoonotic Diseases. - : Mary Ann Liebert. - 1530-3667 .- 1557-7759. ; 22:5, s. 297-299
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Tidskriftsartikel (refereegranskat)abstract
- Pathogens might affect behavior of infected reservoir hosts and hence their trappability, which could bias population estimates of pathogen prevalence. In this study, we used snap-trapping data on Puumala orthohantavirus (PUUV)-infected (n = 1619) and noninfected (n = 6940) bank voles (Myodes glareolus) from five vole cycles, normally representing increase, peak, and decline phase, to evaluate if infection status affected trapping success. If PUUV infection, as previously suggested, increases activity and/or mobility, we would expect a higher proportion of infected than noninfected specimens in the first trapping night. However, the proportion of PUUV-infected voles did not differ across the three trapping nights. We conclude that PUUV infection did not affect trapping success, confirming snap trapping as an appropriate trapping method for studies on PUUV prevalence and likely other orthohantaviruses.
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| 8. |
- Ecke, Frauke, et al.
(författare)
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Selective Predation by Owls on Infected Bank Voles (Myodes glareolus) as a Possible Sentinel of Tularemia Outbreaks
- 2020
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Ingår i: Vector Borne and Zoonotic Diseases. - : Mary Ann Liebert. - 1530-3667 .- 1557-7759. ; 20:8, s. 630-632
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Tidskriftsartikel (refereegranskat)abstract
- Tularemia is a widely spread zoonotic disease in the northern hemisphere, caused by the bacterium Francisella tularensis. In humans, tularemia is an acute febrile illness with incidence peaks in late summer to early autumn of outbreak years, but there is no early warning system in place that can reduce the impact of disease by providing timely risk information. In this study, we revisit previously unpublished data on F. tularensis in water, sediment, soil, and small mammals from 1984 in northern Sweden. In addition, we used human case data from the national surveillance system for tularemia in the same year. In the environmental and small mammal material, bank vole (Myodes glareolus) samples from urine and bladder were the only samples that tested positive for F. tularensis. The prevalence of F. tularensis among trapped bank voles was 13.5%, although all six bank voles that were retrieved from owl nest boxes in early May tested positive. Forty-two human tularemia cases were reported from August to December in 1984. Based on these results, we encourage investigating the potential role of tularemia-infected bank voles retrieved from owl nest boxes in spring as an early warning for outbreaks of tularemia among humans in summer and autumn of the same year.
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| 9. |
- Elfving, Karin, et al.
(författare)
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Serologic and Molecular Prevalence of Rickettsia helvetica and Anaplasma phagocytophilum in Wild Cervids and Domestic Mammals in the Central Parts of Sweden
- 2015
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Ingår i: Vector Borne and Zoonotic Diseases. - : Mary Ann Liebert Inc. - 1530-3667 .- 1557-7759. ; 15:9, s. 529-534
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Tidskriftsartikel (refereegranskat)abstract
- Both Rickettsia helvetica and Anaplasma phagocytophilum are common in Ixodes ricinus ticks in Sweden. Knowledge is limited regarding different animal species' competence to act as reservoirs for these organism. For this reason, blood samples were collected from wild cervids (roe deer, moose) and domestic mammals (horse, cat, dog) in central Sweden, and sera were tested using immunofluorescence assay to detect antibodies against spotted fever rickettsiae using Rickettsia helvetica as antigen. Sera with a titer >= 1:64 were considered as positive, and 23.1% (104/450) of the animals scored positive. The prevalence of seropositivity was 21.5% (23/107) in roe deer, 23.3% (21/90) in moose, 36.5% (23/63) in horses, 22.1% (19/90) in cats, and 17.0% (17/100) in dogs. PCR analysis of 113 spleen samples from moose and sheep from the corresponding areas were all negative for rickettsial DNA. In roe deer, 85% (91/107) also tested seropositive for A. phagocytophilum with a titer cutoff of 1:128. The findings indicate that the surveyed animal species are commonly exposed to rickettsiae and roe deer also to A. phagocytophilum.
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| 10. |
- Elväng, Annelie, et al.
(författare)
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Sequencing of a Tick-Borne Encephalitis Virus from Ixodes ricinus Reveals a Thermosensitive RNA Switch Significant for Virus Propagation in Ectothermic Arthropods
- 2011
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Ingår i: Vector Borne and Zoonotic Diseases. - : Mary Ann Liebert Inc. - 1530-3667 .- 1557-7759. ; 11:6, s. 649-658
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Tidskriftsartikel (refereegranskat)abstract
- Tick-borne encephalitis virus (TBEV) is a flavivirus with major impact on global health. The geographical TBEV distribution is expanding, thus making it pivotal to further characterize the natural virus populations. In this study, we completed the earlier partial sequencing of a TBEV pulled out of a pool of RNA extracted from 115 ticks collected on Torö in the Stockholm archipelago. The total RNA was sufficient for all sequencing of a TBEV genome (Torö-2003), without conventional enrichment procedures such as cell culturing or suckling mice amplification. To our knowledge, this is the first time that the genome of TBEV has been sequenced directly from an arthropod reservoir. The Torö-2003 sequence has been characterized and compared with other TBE viruses. In silico analyses of secondary RNA structures formed by the two untranslated regions revealed a temperature-sensitive structural shift between a closed replicative form and an open AUG accessible form, analogous to a recently described bacterial thermoswitch. Additionally, novel phylogenetic conserved structures were identified in the variable part of the 3′-untranslated region, and their sequence and structure similarity when compared with earlier identified structures suggests an enhancing function on virus replication and translation. We propose that the thermo-switch mechanism may explain the low TBEV prevalence often observed in environmentally sampled ticks. Finally, we were able to detect variations that help in the understanding of virus adaptations to varied environmental temperatures and mammalian hosts through a comparative approach that compares RNA folding dynamics between strains with different mammalian cell passage histories.
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