| 1. |
|
|
| 2. |
- Jaenson, Thomas G.T. 1948-, et al.
(författare)
-
The importance of wildlife in the ecology and epidemiology of the TBE virus in Sweden: incidence of human TBE correlates with abundance of deer and hares
- 2018
-
Ingår i: Parasites & Vectors. - : Springer Science and Business Media LLC. - 1756-3305. ; 11
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Tick-borne encephalitis (TBE) is one tick-transmitted disease where the human incidence has increased in some European regions during the last two decades. We aim to find the most important factors causing the increasing incidence of human TBE in Sweden. Based on a review of published data we presume that certain temperature-related variables and the population densities of transmission hosts, i.e. small mammals, and of primary tick maintenance hosts, i.e. cervids and lagomorphs, of the TBE virus vector Ixodes ricinus, are among the potentially most important factors affecting the TBE incidence. Therefore, we compare hunting data of the major tick maintenance hosts and two of their important predators, and four climatic variables with the annual numbers of human cases of neuroinvasive TBE. Data for six Swedish regions where human TBE incidence is high or has recently increased are examined by a time-series analysis. Results from the six regions are combined using a meta-analytical method.Results: With a one-year time lag, the roe deer (Capreolus capreolus), red deer (Cervus elaphus), mountain hare (Lepus timidus) and European hare (Lepus europaeus) showed positive covariance; the Eurasian elk (moose, Alces alces) and fallow deer (Dama dama) negative covariance; whereas the wild boar (Sus scrofa), lynx (Lynx lynx), red fox (Vulpes vulpes) and the four climate parameters showed no significant covariance with TBE incidence. All game species combined showed positive covariance.Conclusions: The epidemiology of TBE varies with time and geography and depends on numerous factors, i.a. climate, virus genotypes, and densities of vectors, tick maintenance hosts and transmission hosts. This study suggests that the increased availability of deer to I. ricinus over large areas of potential tick habitats in southern Sweden increased the density and range of I. ricinus and created new TBEV foci, which resulted in increased incidence of human TBE. New foci may be established by TBE virus-infected birds, or by birds or migrating mammals infested with TBEV-infected ticks. Generally, persistence of TBE virus foci appears to require presence of transmission-competent small mammals, especially mice (Apodemus spp.) or bank voles (Myodes glareolus).
|
|
| 3. |
- Hoffman, Tove, et al.
(författare)
-
Association between guilds of birds in the African-Western Palaearctic region and the tick species Hyalomma rufipes, one of the main vectors of Crimean-Congo hemorrhagic fever virus
- 2021
-
Ingår i: One Health. - : Elsevier. - 2352-7714. ; 13
-
Tidskriftsartikel (refereegranskat)abstract
- IntroductionThe ecology of the vertebrate host contributes to the geographical range expansion of ticks. In this study, we investigated which tick taxa that infest and are dispersed by birds along African-Western Palaearctic flyways during northward migration, and whether bird ecology was associated with tick taxa.Materials and methodsTicks were collected from birds trapped at bird observatories in Spain, Italy, Greece, and Israel during the spring migration of 2014 and 2015, using mist nets. The tick-infested bird species were classified into guilds, using different combinations of the variables: migration distance, wintering region, foraging behaviour, and winter habitat. Ticks were molecularly determined to genus and species level by sequencing fragments of the 12S ribosomal DNA (rDNA) gene and by phylogenetic inference, using the Maximum Likelihood algorithm. Data were analysed using descriptive measures, graphs, Chi2 tests, the Tukey-Kramer test, and a parametric linear model (generalized linear model) in order to analyse and adjust for characteristics in the bird guilds and their relationship to collected tick taxa.ResultsMost (84.2%) of the 10,209 trapped birds were long-distance migrants, of which 2.4% were infested by ticks. The most common tick species was Hyalomma rufipes (77.7%; 447/575), a known vector and reservoir of Crimean-Congo hemorrhagic fever virus. Bird guilds containing only long-distance migrants with wintering areas in Africa were associated with the tick species H. rufipes (p < 0.0001). Furthermore, bird winter habitat was associated with H. rufipes (p = 0.003); with bird species overwintering in open habitat (p = 0.014) and wetlands (p = 0.046) having significantly more H. rufipes as compared to birds with a winter habitat comprising forest and shrubs (p = 0.82).ConclusionsWith climate change, the likelihood of establishment of permanent Hyalomma populations in central and northern Europe is increasing. Thus, surveillance programs for monitoring the risk of introduction and establishment of H. rufipes in the Western-Palaearctic should be established. Our study suggests that migratory bird species wintering in African open habitats and wetlands are good candidates for monitoring potential introduction.
|
|
| 4. |
- Hoffman, Tove, et al.
(författare)
-
Association between guilds of birds in the African-Western Palaearctic region and the tick species Hyalomma rufipes, one of the main vectors of Crimean-Congo hemorrhagic fever virus.
- 2022
-
Ingår i: Microorganisms. - : MDPI AG. - 2076-2607. ; 10
-
Tidskriftsartikel (refereegranskat)abstract
- The migratory behavior of wild birds contributes to the geographical spread of ticks and their microorganisms. In this study, we aimed to investigate the dispersal and co-occurrence of Francisella and spotted fever group Rickettsia (SFGR) in ticks infesting birds migrating northward in the African-Western Palaearctic region (AWPR). Birds were trapped with mist nests across the Mediterranean basin during the 2014 and 2015 spring migration. In total, 575 ticks were collected from 244 birds. We screened the ticks for the species Francisella tularensis, the genus Francisella, and SFGR by microfluidic real-time PCR. Confirmatory analyses and metagenomic sequencing were performed on tick samples that putatively tested positive for F. tularensis during initial screenings. Hyalomma rufipes was the most common tick species and had a high prevalence of Francisella, including co-occurrence of Francisella and SFGR. Metagenomic analysis of total DNA extracted from two H. rufipes confirmed the presence of Francisella, Rickettsia, and Midichloria. Average nucleotide identity and phylogenetic inference indicated the highest identity of the metagenome-assembled genomes to a Francisella-like endosymbiont (FLE), Rickettsia aeschlimannii, and Midichloria mitochondrii. The results of this study suggest that (i) FLE- and SFGR-containing ticks are dispersed by northbound migratory birds in the AWPR, (ii) H. rufipes likely is not involved in transmission of F. tularensis in the AWPR, and (iii) a dual endosymbiosis of FLEs and Midichloria may support some of the nutritional requirements of H. rufipes.
|
|
| 5. |
- Hoffman, Tove, et al.
(författare)
-
Co-occurrence of Francisella and spotted fever group Rickettsia in avian-associated Hyalomma rufipes
- 2022
-
Ingår i: Microorganisms. - : MDPI. - 2076-2607. ; 10:7
-
Tidskriftsartikel (refereegranskat)abstract
- Introduction: The migratory behaviour of wild birds aids in the geographical spread of ticks and their microorganisms. Ticks are known to harbor both pathogenic and symbiotic bacteria - such as species of the genera Francisella, Rickettsia,and Midichloria - and multiple bacterial species may occur within them. Francisella occurs in different tick taxa andconsists of closely related pathogenic and non-pathogenic species. Spotted fever group Rickettsia are transmitted to humans by different tick genera and are emerging human pathogens in Europe. The aims of this study were to investigate dispersal of Francisella as well as co-occurrence of Francisella and spotted fever group Rickettsia in ticks infesting northward migrating birds in the African-Western Palaearctic region.Materials and methods: Birds were trapped using mist nets at bird observatories in Spain, Italy, Greece, and Israel during their spring migration of 2014 and 2015. Ticks were screened for the genus Francisella, the species Francisella tularensis, and spotted fever group Rickettsia by microfluidic qPCR. Ticks with putative positive results for F. tularensiswere subjected to confirmation analyses, metagenomics analysis, enrichment, and whole genome sequencing.Results: There was a high prevalence of Francisella species (76.7%) and co-occurrence of Francisella species and spotted fever group Rickettsia (50.6%) in the tick species Hyalomma rufipes. Two H. rufipes yielded putative positive test results for the human pathogen F. tularensis during initial screening. Metagenomics analysis revealed presence of Francisella sp., Rickettsia sp., and Midichloria sp. DNA in the two H. rufipes ticks. The levels of Rickettsia and Midichloria DNA were relatively high while the level of Francisella DNA was low and required enrichment for the construction of metagenome-assembled genomes. Phylogenetic inference and calculations of the average nucleotide identity (ANI) indicated that: i) the Francisella genomes belonged to the Francisella-like endosymbiont (FLE) group in Clade 1 of Francisella and had highest sequence identity to an FLE found in Ornithodoros moubata (ANI: 96.7/97.0%), ii) the Rickettsia genomes had highest resemblance to Rickettsia aeschlimannii (ANI: 98.8 - 99.9%), and iii) the Midichloria genomes resembled Midichloria mitochondrii (ANI: 91.5 - 92.3%).Conclusions: The results of this study suggest ticks containing Francisella species, FLEs, and spotted fever groupRickettsia are dispersed by northbound migratory birds in the African-Western Palaearctic and suggest H. rufipes may not be involved in the transmission of F. tularensis in the study region. Future studies should aim at confirming the prevalence of Francisella spp. and spotted fever group Rickettsia in H. rufipes, in addition to focusing on the influence of FLEs on H. rufipes and their interaction with pathogenic and symbiotic bacteria of the genera Rickettsia and Midichloria.
|
|
| 6. |
- Hoffman, Tove, et al.
(författare)
-
Co-Occurrence of Francisella, Spotted Fever Group Rickettsia, and Midichloria in Avian-Associated Hyalomma rufipes
- 2022
-
Ingår i: Microorganisms. - : MDPI. - 2076-2607. ; 10:7
-
Tidskriftsartikel (refereegranskat)abstract
- The migratory behavior of wild birds contributes to the geographical spread of ticks and their microorganisms. In this study, we aimed to investigate the dispersal and co-occurrence of Francisella and spotted fever group Rickettsia (SFGR) in ticks infesting birds migrating northward in the African-Western Palaearctic region (AWPR). Birds were trapped with mist nests across the Mediterranean basin during the 2014 and 2015 spring migration. In total, 575 ticks were collected from 244 birds. We screened the ticks for the species Francisella tularensis, the genus Francisella, and SFGR by microfluidic real-time PCR. Confirmatory analyses and metagenomic sequencing were performed on tick samples that putatively tested positive for F. tularensis during initial screenings. Hyalomma rufipes was the most common tick species and had a high prevalence of Francisella, including co-occurrence of Francisella and SFGR. Metagenomic analysis of total DNA extracted from two H. rufipes confirmed the presence of Francisella, Rickettsia, and Midichloria. Average nucleotide identity and phylogenetic inference indicated the highest identity of the metagenome-assembled genomes to a Francisella-like endosymbiont (FLE), Rickettsia aeschlimannii, and Midichloria mitochondrii. The results of this study suggest that (i) FLE- and SFGR-containing ticks are dispersed by northbound migratory birds in the AWPR, (ii) H. rufipes likely is not involved in transmission of F. tularensis in the AWPR, and (iii) a dual endosymbiosis of FLEs and Midichloria may support some of the nutritional requirements of H. rufipes.
|
|
| 7. |
- Jaenson, T. G. T., et al.
(författare)
-
Evaluation of extracts and oils of mosquito (Diptera : Culicidae) repellent plants from Sweden and Guinea-Bissau
- 2006
-
Ingår i: Journal of medical entomology. - : Oxford University Press (OUP). - 0022-2585 .- 1938-2928. ; 43:1, s. 113-119
-
Tidskriftsartikel (refereegranskat)abstract
- In laboratory tests, ethyl acetate extracts of Hyptis, suaveolens Poit. from Guinea-Bissau and Rhododendon tomentosum (Stokes) H. Harmaja (formerly Ledum palustre L.) and Myrica gale L. significantly reduced probing activity of Aedes aegypti (L.). In the field in southern Sweden, extracts of leaves of R. tomentosum, M. gale, and Achillea millefolium L. significantly reduced biting by Aedes mosquitoes. Volatile compounds from M. gale, R. tomentosum, A. millefolium, and H. suaveolens were collected by solid phase microextraction (SPME). Alternatively, compounds in the plants were subjected to extraction by organic solvents of different polarities or by steam distillation and collection by SPME. Compounds collected were identified by gas chromatography-mass spectrometry. Leaves of H. suaveolens contained mainly beta-caryophyllene, bergamotene, and terpinolene. The volatile fraction of an ethyl acetate extract of H. suaveolens was collected by SPME and included beta-caryophyllene, (-) -sabinene, beta-pinene, limonene, alpha-pinene, and bergamotene. The main volatiles detected were alpha-pinene, alpha-phellandrene, myrcene, and limonene from M. gale leaves or inflorescences; pcymene, sabinene, and terpinyl acetate from leaves of R. tornentoston; and (-)-germacrene D, beta-pinene, sabinene, and alpha-pinene from A. millefolium leaves or inflorescences. The selected plant species contained numerous volatiles known to have insecticidal, acaricidal, pesticidal, and/orinsect repellent properties.
|
|
| 8. |
- Jaenson, T. G. T., et al.
(författare)
-
Evaluation of extracts and oils of tick-repellent plants from Sweden
- 2005
-
Ingår i: Medical and Veterinary Entomology. - : Wiley. - 0269-283X .- 1365-2915. ; 19:4, s. 345-352
-
Tidskriftsartikel (refereegranskat)abstract
- Leaves of Myrica gale Linnaeus (Myricaceae), Rhododendron tomentosum (Stokes) H. Harmaja (formerly Ledum palustre Linnaeus: Ericaceae) and Artemisia absinthium Linnaeus (Asteraceae) were extracted with organic solvents of different polarities and the essential oils of leaves were obtained by steam distillation. The extracts or oils were tested in the laboratory for repellency against host-seeking nymphs of Ixodes ricinus Linnaeus (Acari: Ixodidae). Rhododendron tomentosum oil, 10%, diluted in acetone, exhibited 95% repellency; R. tomentosum and A. absinthium extracts in ethyl acetate, > 70% repellency; A. absinthium extract in hexane, similar to 62% repellency; and M. gale oil, 10%, similar to 50% repellency on I. ricinus nymphs. Compounds in the leaf extracts or in the oils were collected by solid phase microextraction (SPME) and identified by gas chromatography-mass spectrometry (GC-MS) and/or MS. Characteristic volatiles detected from oil or extract of M. gale were the monoterpenes 1,8-cineole, alpha-terpineol, 4-terpineol and thujenol; and of R. tomentosum myrcene and palustrol. Characteristic volatiles from leaf extracts of A. absinthium were sabinene, oxygenated monoterpenes, e.g. thujenol and linalool, and geranyl acetate. Each plant species synthesized numerous volatiles known to exhibit acaricidal, insecticidal, 'pesticidal' and/or arthropod repellent properties. These plants may be useful sources of chemicals for the control of arthropods of medical, veterinary or agricultural importance.
|
|
| 9. |
- Lilja, T., et al.
(författare)
-
Single nucleotide polymorphism analysis of the ITS2 region of two sympatric malaria mosquito species in Sweden : Anopheles daciaeandAnopheles messeae
- 2020
-
Ingår i: Medical and Veterinary Entomology. - : WILEY. - 0269-283X .- 1365-2915. ; 34:3, s. 364-368
-
Tidskriftsartikel (refereegranskat)abstract
- Four species of theAnopheles maculipenniscomplex have previously been recorded in Sweden. A recent addition to the complex isAnopheles daciae, which is considered to be closely related to, but distinct fromAnopheles messeae. The original designation ofAn. daciaewas based on five genetic differences (161, 165, 167, 362 and 382) in the second internal transcribed spacer (ITS) 2 of the ribosomal RNA. Further studies have shown that only two nucleotide differences (362 and 382) robustly separate the species. Thirty-threeAn. maculipenniscomplex mosquitoes were collected in the province of Uppland, Sweden. All wereAn. daciaebut showed double peaks for three variable positions (161, 165 and 167). When cloned, the intra-individual nucleotide variation was almost exclusively fixed with either TTC or AAT, originally diagnostic forAn. messaeandAn. daciae, respectively. To further investigate the intra-individual variation, nineAn. daciaeand 11An. messeaewere collected in southern Sweden and their ITS2 fragments were amplified and sequenced using Illumina MiSeq sequencing (Illumina, Inc., San Diego, CA, USA). For the diagnostic nucleotide 382 no intra-individual variation could be detected. However, although eachAn. daciaespecimen carried several ITS2 sequence variants for the four other nucleotides, there was no intra-individual variation in theAn. messeaespecimens.
|
|
| 10. |
|
|
| 11. |
|
|
| 12. |
- 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.
|
|
| 13. |
- de Boer, Hugo J., et al.
(författare)
-
Botanical Repellents and Pesticides Traditionally Used Against Hematophagous Invertebrates in Lao People's Democratic Republic : A Comparative Study of Plants Used in 66 Villages
- 2010
-
Ingår i: Journal of medical entomology. - 0022-2585 .- 1938-2928. ; 47:3, s. 400-414
-
Tidskriftsartikel (refereegranskat)abstract
- Hematophagous parasites such as leeches, ticks, mites, lice, bedbugs, mosquitoes, and myiasis-producing fly larvae are common health problems in Lao People's Democratic Republic. Several arthropod-borne infections, e.g., malaria, dengue fever, and Japanese encephalitis, are endemic there. Effective vector control methods including the use of pesticides, insecticide-treated bed nets, and synthetic and plant-based repellents are important means of control against such invertebrates and the pathogens they may transmit or directly cause. In this study, we documented traditional knowledge on plants that are used to repel or kill hematophagous arthropods, including mosquitoes, bedbugs, human lice, mites and ticks, fly larvae, and blood-sucking leeches. Structured interviews were carried out in 66 villages comprising 17 ethnic groups, covering a range of cultures, throughout Lao People's Democratic Republic. A total of 92 plant species was recorded as traditional repellents (including plants for pesticidal usages) in 123 different plant-ectoparasite combinations. The number and species of plants, and animal taxa repelled (or killed) per plant species differed per region, village, and ethnic group. Traditional use was confirmed in the scientific literature for 74 of these plant species, and for an additional 13 species using literature on closely related species. The use of botanical repellents and pesticides from many plant species is common and widespread in the Lao countryside. In the future, the identification of the active components in certain plants to develop more optimal, inexpensive repellents, insecticides, acaricides, or antileech compounds as alternatives to synthetic repellents/pesticides against blood-feeding insects, ticks, mites, and leeches is warranted.
|
|
| 14. |
- Estrada-Peña, Agustín, et al.
(författare)
-
Scientific opinion on geographic distribution of tick-borne infections and their vectors in Europe and the other regions of the Mediterranean Basin : EFSA Panel on Animal Health and Welfare (AHAW)
- 2010
-
Ingår i: EFSA Journal. - Parma, Italy : European Food Safety Authority. - 1831-4732. ; 8:9, s. 1723 [280 pp.]-
-
Forskningsöversikt (refereegranskat)abstract
- This report is the second of a series of two technical assessments of the role of ticks in transmission of animal diseases and zoonoses in Eurasia. A previous published scientific opinion (EFSA 2010a) focused on two diseases- Crimean-Congo haemorrhagic fever and African swine fever in Eurasia. The aim of this report is to provide a general overview of the geographic distribution of tick species which have proven involvement in the transmission of pathogens causing animal diseases and zoonoses in Eurasia.The report provides a review of the geographic distribution of the relevant tick species and TBDs in Eurasia by producing maps of the region that display the occurrences of ticks and tick borne pathogens. Systematic literature review of available publications for the last 10 years and other available literature from the experts were used in the retrieval of the geographical reported cases for the presence of ticks and tick borne pathogens. The report includes a description of the factors that influence the dynamics of the relevant tick species and identify possible high-risk areas in the EU for introduction considering the biological and ecological characteristics of the ticks and their ability to adapt to new areas. Surveillance tools and control measures for ticks were discussed.Findings from this review have provided evidence of the extent of ticks and TBDs in geographical ranges and the existing risk areas that should be considered as baseline information to assess potential risk of these diseases. The report indicates the validity of using available literature to support the presence of ticks and TBDs without further predication using weather and other environmental factors associated with the survival of the ticks. Surveillance tools for the detection of the ticks and their control measures are discussed in this report. The report concluded that animal and human movement play a significant impact on the spread of the ticks and TBDs. Climate changes and flight pattern of migratory birds can influence the presence and spread of the ticks and TBDs, These two factors acting by themselves have not been determined be responsible for the widespread distribution of ticks.
|
|
| 15. |
- Estrada-Pena, Agustín, et al.
(författare)
-
Scientific opinion on the Role of Tick Vectors in the Epidemiology of Crimean-Congo Hemorrhagic Fever and African Swine Fever in Eurasia : EFSA Panel on Animal Health and Welfare
- 2010
-
Ingår i: EFSA Journal. - Parma, Italy : EFSA. - 1831-4732. ; 8:8, s. 1-156
-
Tidskriftsartikel (refereegranskat)abstract
- The report provides an update on the role of the tick vectors in the epidemiology of African swine fever (ASF) and Crimean and Congo haemorrhagic fever (CCHF) in Eurasia, specifically to review of the geographical distribution of the relevant ticks with presentation of maps of their occurrence in Europe and Mediterranean basin; a description of the factors that define the relevant tick population dynamics and identify possible high risk areas in the EU; an update on the role of tick vectors associated with CCHF and ASF in Eurasia; and reviews available methods for the control of the relevant tick vectors. Data were collected through systematic literature review in a database from which maps of geographic distribution of ticks, CCHF virus and ASF virus were issued. The main vectors for CCHF are Hyalomma spp, Increase in the number of fragmented areas and the degradation of agricultural lands to bush lands are the two main factors in the creation of new foci of CCHF in endemic areas. Movement of livestock and wildlife species, which may carry infected ticks, contributes to the spread of the infection. The Middle East and Balkan countries are the most likely sources of introduction of CCHFV into other European countries. All the Ornithodoros species investigated so far can become infective with ASF virus and are perhaps biological vectors. These ticks are important in maintaining the local foci of the ASFV, but do not play an active role in the geographical spread of the virus. Wild boars have never been found infested by Ornithodoros spp. because wild boars normally do not rest inside protected burrows, but above the ground. There is no single ideal solution to the control of ticks relevant for CCHF or ASF. The integrated control approach is probably the most effective.
|
|
| 16. |
- 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.
|
|
| 17. |
- Hagman, Karl, et al.
(författare)
-
On the potential roles of ticks and migrating birds in the ecology of West Nile virus
- 2014
-
Ingår i: Infection Ecology & Epidemiology. - : Informa UK Limited. - 2000-8686. ; 4
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Mosquitoes are the primary vectors of West Nile virus (WNV). Ticks have, however, been suggested to be potential reservoirs of WNV. In order to investigate their role in the spread of the virus, ticks, which had been collected from birds migrating northwards from Africa to Europe, were analyzed for the potential presence of WNV-RNA.METHODS: On the Mediterranean islands Capri and Antikythira a total of 14,824 birds were captured and investigated from which 747 ticks were collected.RESULTS AND CONCLUSION: Most of the identified ticks (93%) were nymphs and larvae of Hyalomma marginatum sensu lato, most of which were or appear to be Hyalomma rufipes. Of these ticks 729 were individually screened for WNV-RNA. None of the ticks was found to be WNV positive. Thus, there was no evidence that Hyalomma marginatum s.l. ticks play a role in the spread of WNV from Africa to Europe.
|
|
| 18. |
- Hoffman, Tove, et al.
(författare)
-
A divergent Anaplasma phagocytophilum variant in an Ixodes tick from a migratory bird; Mediterranean basin
- 2020
-
Ingår i: Infection Ecology & Epidemiology. - : Informa UK Limited. - 2000-8686. ; 10:1
-
Tidskriftsartikel (refereegranskat)abstract
- Anaplasma phagocytophilum (AP) has vast geographical and host ranges and causes disease in humans and domesticated animals. We investigated the role of northward migratory birds in the dispersal of tick-borne AP in the African-Western Palearctic.Ticks were collected from northward migratory birds trapped during spring migration of 2010 at two localities in the central Mediterranean Sea. AP DNA was detected by PCR (gltA and 16S rRNA) and variant determination was performed using ankA sequences.In total, 358 ticks were collected. One of 19 ticks determined as Ixodes was confirmed positive for AP DNA. The tick was collected from a woodchat shrike (Lanius senator senator) trapped in Greece, and molecularly determined to belong to the I. ricinus complex and sharing highest (95%) 16S RNA sequence identity to I. gibbosus. The ankA AP sequence exhibited highest similarity to sequences from rodents and shrews (82%) and ruminants (80%). Phylogenetic analyses placed it convincingly outside other clades, suggesting that it represents a novel AP variant.The divergent Ixodes species harboring a novel AP variant could either indicate an enzootic cycle involving co-evolution with birds, or dissemination from other regions by avian migration. None of the 331 Hyalomma marginatum sensu lato ticks, all immature stages, were positive for AP DNA, lending no evidence for the involvement of Hyalomma ticks transported by birds in the ecology of AP.
|
|
| 19. |
- Hoffman, Tove, et al.
(författare)
-
Alkhurma Hemorrhagic Fever Virus RNA in Hyalomma rufipes Ticks Infesting Migratory Birds, Europe and Asia Minor
- 2018
-
Ingår i: Emerging Infectious Diseases. - Atlanta, United States : U.S. Department of Health and Human Services * Centers for Disease Control and Prevention. - 1080-6040 .- 1080-6059. ; 24:5, s. 879-882
-
Tidskriftsartikel (refereegranskat)abstract
- Alkhurma hemorrhagic fever virus RNA was detected in immature Hyalomma rufipes ticks infesting northward migratory birds caught in the North Mediterranean Basin. This finding suggests a role for birds in the ecology of the Alkhurma hemorrhagic fever virus and a potential mechanism for dissemination to novel regions. Increased surveillance is warranted.
|
|
| 20. |
- Jaenson, Thomas G.T. 1948-, et al.
(författare)
-
Coinfection of Babesia and Borrelia in the Tick Ixodes ricinus-A Neglected Public Health Issue in Europe?
- 2024
-
Ingår i: Pathogens. - : MDPI. - 2076-0817. ; 13:1
-
Forskningsöversikt (refereegranskat)abstract
- Ixodes ricinus nymphs and adults removed from humans, and larvae and nymphs from birds, have been analysed for infection with Babesia species and Borrelia species previously in separately published studies. Here, we use the same data set to explore the coinfection pattern of Babesia and Borrelia species in the ticks. We also provide an overview of the ecology and potential public health importance in Sweden of I. ricinus infected both with zoonotic Babesia and Borrelia species. Among 1952 nymphs and adult ticks removed from humans, 3.1% were PCR-positive for Babesia spp. Of these Babesia-positive ticks, 43% were simultaneously Borrelia-positive. Among 1046 immatures of I. ricinus removed from birds, 2.5% were Babesia-positive, of which 38% were coinfected with Borrelia species. This study shows that in I. ricinus infesting humans or birds in Sweden, potentially zoonotic Babesia protozoa sometimes co-occur with human-pathogenic Borrelia spp. Diagnostic tests for Babesia spp. infection are rarely performed in Europe, and the medical significance of this pathogen in Europe could be underestimated.
|
|
| 21. |
|
|
| 22. |
|
|
| 23. |
|
|
| 24. |
|
|
| 25. |
- Jaenson, Thomas G. T., et al.
(författare)
-
First evidence of established populations of the taiga tick Ixodes persulcatus (Acari: Ixodidae) in Sweden
- 2016
-
Ingår i: Parasites & Vectors. - : Springer Science and Business Media LLC. - 1756-3305. ; 9
-
Tidskriftsartikel (refereegranskat)abstract
- Background: The tick species Ixodes ricinus and I. persulcatus are of exceptional medical importance in the western and eastern parts, respectively, of the Palaearctic region. In Russia and Finland the range of I. persulcatus has recently increased. In Finland the first records of I. persulcatus are from 2004. The apparent expansion of its range in Finland prompted us to investigate if I. persulcatus also occurs in Sweden. Methods: Dog owners and hunters in the coastal areas of northern Sweden provided information about localities where ticks could be present. In May-August 2015 we used the cloth-dragging method in 36 localities potentially harbouring ticks in the Bothnian Bay area, province Norrbotten (NB) of northern Sweden. Further to the south in the provinces Vasterbotten (VB) and Uppland (UP) eight localities were similarly investigated. Results: Ixodes persulcatus was detected in 9 of 36 field localities in the Bothnian Bay area. Nymphs, adult males and adult females (n = 46 ticks) of I. persulcatus were present mainly in Alnus incana - Sorbus aucuparia - Picea abies - Pinus sylvestris vegetation communities on islands in the Bothnian Bay. Some of these I. persulcatus populations seem to be the most northerly populations so far recorded of this species. Dog owners asserted that their dogs became tick-infested on these islands for the first time 7-8 years ago. Moose (Alces alces), hares (Lepus timidus), domestic dogs (Canis lupus familiaris) and ground-feeding birds are the most likely carriers dispersing I. persulcatus in this area. All ticks (n = 124) from the more southern provinces of VB and UP were identified as I. ricinus. Conclusions: The geographical range of the taiga tick has recently expanded into northern Sweden. Increased information about prophylactic, anti-tick measures should be directed to people living in or visiting the coastal areas and islands of the Baltic Bay.
|
|
| 26. |
- Jaenson, Thomas G. T., 1948-, et al.
(författare)
-
First Record of a Suspected Human-Pathogenic Borrelia Species in Populations of the Bat Tick Carios vespertilionis in Sweden
- 2021
-
Ingår i: Microorganisms. - : MDPI. - 2076-2607. ; 9:5
-
Tidskriftsartikel (refereegranskat)abstract
- The bat tick Carios vespertilionis has been reported from Sweden to occasionally feed on humans resulting in disease symptoms. The aim of this study was to investigate C. vespertilionis as a potential vector and reservoir of Borrelia species. In 2015 and 2018 in south-central Sweden, C. vespertilionis ticks were collected from a wooden bat box harboring Soprano pipistrelle bats, Pipistrellus pygmaeus. In addition, one C. vespertilionis tick found inside a house in southern Sweden in 2019 was collected. Ticks were screened for Borrelia spp. using a genus-specific quantitative PCR assay. The Borrelia species of the positive specimens were determined by conventional PCR followed by DNA sequencing and phylogenetic analyses. A total of 24% (22 of 92) of the analyzed C. vespertilionis ticks were Borrelia-positive. Phylogenetic analyses indicate that the bacteria belong to the relapsing fever group of borreliae; some of them appear to be identical with Borrelia sp. CPB1, a spirochete only found twice before-in the United Kingdom and in France. Our results also indicate a temporal and spatial distribution of this Borrelia species. Since C. vespertilionis occasionally bites humans, and since it exhibits a high prevalence of Borrelia bacteria, it is possible that it presents a risk of human disease. Further studies are needed to characterize Borrelia sp. CPB1 to determine if it is human-pathogenic and to determine if C. vespertilionis is a vector and/or reservoir of this agent.
|
|
| 27. |
- Jaenson, Thomas G.T. 1948-, et al.
(författare)
-
First records of adult Hyalomma marginatum and H. rufipes ticks (Acari: Ixodidae) in Sweden
- 2020
-
Ingår i: Ticks and Tick-borne Diseases. - : Elsevier BV. - 1877-959X .- 1877-9603. ; 11:3
-
Tidskriftsartikel (refereegranskat)abstract
- From July 2018 to January 2019 we recorded 41 specimens of adult Hyalomma ticks, which had been found on horses, cattle or humans in 14 Swedish provinces. In 20 cases we received tick specimens, which were identified morphologically as adults of H. marginatum (n = 11) or H. rufipes (n = 9). These are the first documented records in Sweden of adults of H. marginatum and H. rufipes. Molecular tests for Crimean-Congo haemorrhagic fever virus and piroplasms (Babesia spp. and Theileria spp.) proved negative; 12 out of 20 tested specimens were positive for rickettsiae (R. aeschlimannii was identified in 11 of the ticks). All ticks originated from people or animals that had not been abroad during the previous two months. These data suggest (i) that the adult Hyalomma ticks originated from immature ticks, which had been brought from the south by migratory birds arriving in Sweden during spring or early summer; and that (ii) due to the exceptionally warm summer of 2018 these immature ticks had been able to develop to the adult stage in the summer and/or autumn of the same year. The rapidly changing climate most likely now permits these two Hyalomma species to develop to the adult, reproductive stage in northern Europe. There is consequently a need to revise the risk maps on the potential geographic occurrence of relevant tick species and related tick-borne pathogens in Sweden and in the neighbouring countries.
|
|
| 28. |
- Jaenson, Thomas G.T. 1948-, et al.
(författare)
-
First records of tick-borne pathogens in populations of the taiga tick Ixodes persulcatus in Sweden
- 2019
-
Ingår i: Parasites & Vectors. - : BMC. - 1756-3305. ; 12
-
Tidskriftsartikel (refereegranskat)abstract
- Background: The common tick Ixodes ricinus and the taiga tick I. persulcatus are the main tick vectors of Borrelia spirochaetes, TBE virus (TBEV) and of several other zoonotic pathogens in the western and eastern areas, respectively of the Palaearctic region. Recently, populations of the taiga tick were, for the first time, detected in northern Sweden. This prompted us to investigate if they harbour human pathogens.Methods: A total of 276 I. persulcatus ticks (136 males, 126 females and 14 nymphs) and one I. ricinus nymph was collected by the cloth-dragging method in northern Sweden in July-August 2015 and May-July 2016. In addition, 8 males and 10 females of I. persulcatus were collected from two dogs (16 and 2 ticks, respectively) in two of the localities. All ticks were microscopically and molecularly identified to developmental stage and species and screened for B. burgdorferi (sensu lato), B. miyamotoi, Anaplasma phagocytophilum, Rickettsia spp., Neoehrlichia mikurensis, Babesia spp. and TBEV using real-time PCR followed by species identification by sequencing the PCR-products of conventional PCR assays.Results: Of the ticks collected by the cloth-dragging method, 55% (152/277) were positive for Borrelia. There was no significant difference between the proportions of Borrelia-infected nymphs (33%, 5/15) and Borrelia-infected adult ticks (56%, 147/262), and no significant difference between the proportions of Borrelia-infected males (54%, 74/136) and Borrelia-infected females (58%, 73/126). Three different Borrelia species were identified. Borrelia afzelii was the predominant species and detected in 46% of all Borrelia-infected ticks followed by B. garinii, 35%, B. valaisiana, 1%, and mixed infections of different Borrelia species, 1%; 17% of all Borrelia-infections were untypeable. One I. persulcatus female contained Rickettsia helvetica, and one nymph contained Rickettsia sp. Of the 277 ticks analysed, all were negative for A. phagocytophilum, Babesia spp., Borrelia miyamotoi, N. mikurensis and TBEV. The ticks collected from the two dogs were negative for all pathogens examined except for Borrelia spp., that was detected in 5 out of 16 ticks removed from one of the dogs.Conclusions: To our knowledge, this is the first time that I. persulcatus from Sweden has been analysed for the presence of tick-borne pathogens. The examined tick populations had a low diversity of tick-borne pathogens but a high prevalence of B. burgdorferi (s.l.).
|
|
| 29. |
- Jaenson, Thomas G. T., 1948-, et al.
(författare)
-
"Fågelloppor" kan ha varit fågelkvalster
- 2010
-
Ingår i: Läkartidningen. - 0023-7205 .- 1652-7518. ; 107:29-31, s. 1791-1792
-
Tidskriftsartikel (populärvet., debatt m.m.)
|
|
| 30. |
|
|
| 31. |
|
|
| 32. |
|
|
| 33. |
- 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.
|
|
| 34. |
|
|
| 35. |
- Jaenson, Thomas G. T., et al.
(författare)
-
The ecology of lyme borreliosis in Sweden
- 1994. - 1
-
Ingår i: Lyme borreliosis. - New York : Springer-Verlag New York. - 9781461524151 ; , s. 113-115
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The geographical distribution of Lyme borreliosis (Lb) in the North European countries appears to coincide with the geographical distribution of the principal vector, the common tick Ixodes ricinus. We have found that in Sweden this tick species occurs in the southern and south-central parts of the country and along the coast of northern Sweden. This area corresponds with the distributional area of Lyme borreliosis. I. ricinus, and thus also Borrelia burgdorferi s.l., are in general not present in the interior of North Sweden, presumably because the climate is too harsh for the vector.
|
|
| 36. |
- Jaenson, Thomas G.T. 1948-, et al.
(författare)
-
The range of Ixodes ricinus and the risk of contracting Lyme borreliosis will increase northwards when the vegetation period becomes longer
- 2011
-
Ingår i: Ticks and Tick-borne Diseases. - : Elsevier BV. - 1877-959X .- 1877-9603. ; 2:1, s. 44-49
-
Tidskriftsartikel (refereegranskat)abstract
- In Sweden, the geographical distribution of Lyme borreliosis corresponds to that of its vector kodes ricinus. Both tick activity and the length of the vegetation period are determined by daily mean temperatures >= 5 degrees C. We analysed the correspondence between the distribution of I. ricinus in Sweden, the start date, end date, and length of the vegetation period, and the distributions of tick habitat-associated plant species. The geographical distribution oil. ricinus in Sweden corresponds to a vegetation period averaging 170 days, an early start (before May 1st) of spring, and to the distribution of black alder (Alnus glutinosa). Based on scenario models for these parameters, changes in the range and abundance of I. ricinus were projected for the periods 2011-2040, 2041-2070, and 2071-2100. We conclude that climate change during this century will probably increase the geographic range of I. ricinus as vegetation communities and mammals associated with high tick densities will increase their geographic ranges due to a markedly prolonged vegetation period. By the end of this century, the ranges of I. ricinus and Borrelia burgdorferi sensu lato may, in suitable habitats, encompass most of Sweden, Norway, and Finland as far as 70 degrees N, except the mountainous regions. This will lead to an increased Lyme borreliosis risk in northern Scandinavia.
|
|
| 37. |
- Jaenson, Thomas G.T. 1948-
(författare)
-
Virus-like rods associated with salivary gland hyperplasia in tsetse, Glossina pallidipes
- 1978
-
Ingår i: Transactions of the Royal Society of Tropical Medicine and Hygiene. - : Oxford University Press (OUP). - 0035-9203 .- 1878-3503. ; 72:3, s. 234-238
-
Tidskriftsartikel (refereegranskat)abstract
- Long, virus-like rods were discovered in hyperplastic salivary glands of Glossina pallidipes Austen from Kibwezi Forest (2 ° 27′ S, 37 ° 55′ E), Kenya. The glands were enlarged up to four times the normal diameter. This increase in size was due to a cellular proliferation of the glandular epithelial cells and hypertrophy of their nuclei and cytoplasm. Nuclear and cytoplasmic inclusions were present in the enlarged cells but were not found in cells of normal-sized glands. Electron microscopy revealed many virus-like rods in the abnormal glands. Males with such glands were often completely sterile. Abnormal growth of the ovarioles was a significant feature of young females with hyperplastic glands. Both sexes of wild and laboratory-bred flies were found with enlarged glands. One way of transmission of the trait seems to be from mother to progeny.
|
|
| 38. |
- Jaenson, Thomas G. T., et al.
(författare)
-
Why is tick-borne encephalitis increasing? A review of the key factors causing the increasing incidence of human TBE in Sweden
- 2012
-
Ingår i: Parasites & Vectors. - : Springer Science and Business Media LLC. - 1756-3305. ; 5:184, s. 1-13
-
Forskningsöversikt (refereegranskat)abstract
- The highest annual incidence of human tick-borne encephalitis (TBE) in Sweden ever recorded by the Swedish Institute for Communicable Disease Control (SMI) occurred last year, 2011. The number of TBE cases recorded during 2012 up to 6th August 2012 indicates that the incidence for 2012 could exceed that of 2011. In this review of the ecology and epidemiology of TBE in Sweden our main aim is to analyse the possible reasons behind the gradually increasing incidence of human TBE during the last 20 years. The main TBE virus (TBEV) vector to humans in Sweden is the nymphal stage of the common tick Ixodes ricinus. The main mode of transmission and maintenance of TBEV in the tick population is considered to be when infective nymphs co-feed with uninfected but infectible larvae on rodents. In most locations the roe deer, Capreolus capreolus is the main host for the reproducing adult I. ricinus ticks. The high number of roe deer for more than three decades has resulted in a very large tick population. Deer numbers have, however, gradually declined from the early 1990s to the present. This decline in roe deer numbers most likely made the populations of small rodents, which are reservoir-competent for TBEV, gradually more important as hosts for the immature ticks. Consequently, the abundance of TBEV-infected ticks has increased. Two harsh winters in 2009-2011 caused a more abrupt decline in roe deer numbers. This likely forced a substantial proportion of the "host-seeking" ticks to feed on bank voles (Myodes glareolus), which at that time suddenly had become very numerous, rather than on roe deer. Thus, the bank vole population peak in 2010 most likely caused many tick larvae to feed on reservoir-competent rodents. This presumably resulted in increased transmission of TBEV among ticks and therefore increased the density of infected ticks the following year. The unusually warm, humid weather and the prolonged vegetation period in 2011 permitted nymphs and adult ticks to quest for hosts nearly all days of that year. These weather conditions stimulated many people to spend time outdoors in areas where they were at risk of being attacked by infective nymphs. This resulted in at least 284 human cases of overt TBE. The tick season of 2012 also started early with an exceptionally warm March. The abundance of TBEV-infective "hungry" ticks was presumably still relatively high. Precipitation during June and July was rich and will lead to a "good mushroom season". These factors together are likely to result in a TBE incidence of 2012 similar to or higher than that of 2011.
|
|
| 39. |
|
|
| 40. |
- Labbé, Lisa Sandelin, et al.
(författare)
-
Candidatus Neoehrlichia mikurensis in Ticks from Migrating Birds in Sweden
- 2015
-
Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 10:7
-
Tidskriftsartikel (refereegranskat)abstract
- Candidatus Neoehrlichia mikurensis (CNM; family Anaplasmataceae) was recently recognized as a potential tick-borne human pathogen. The presence of CNM in mammals, in host-seeking Ixodes ticks and in ticks attached to mammals and birds has been reported recently. We investigated the presence of CNM in ornithophagous ticks from migrating birds. A total of 1,150 ticks (582 nymphs, 548 larvae, 18 undetermined ticks and two adult females) collected from 5,365 birds captured in south-eastern Sweden was screened for CNM by molecular methods. The birds represented 65 different species, of which 35 species were infested with one or more ticks. Based on a combination of morphological and molecular species identification, the majority of the ticks were identified as Ixodes ricinus. Samples were initially screened by real-time PCR targeting the CNM 16S rRNA gene, and confirmed by a second real-time PCR targeting the groEL gene. For positive samples, a 1260 base pair fragment of the 16S rRNA gene was sequenced. Based upon bacterial gene sequence identification, 2.1% (24/1150) of the analysed samples were CNM-positive. Twenty-two out of 24 CNM-positive ticks were molecularly identified as I. ricinus nymphs, and the remaining two were identified as I. ricinus based on morphology. The overall CNM prevalence in I. ricinus nymphs was 4.2%. None of the 548 tested larvae was positive. CNM-positive ticks were collected from 10 different bird species. The highest CNM-prevalences were recorded in nymphs collected from common redpoll (Carduelis flammea, 3/7), thrush nightingale (Luscinia luscinia, 2/29) and dunnock (Prunella modularis, 1/17). The 16S rRNA sequences obtained in this study were all identical to each other and to three previously reported European strains, two of which were obtained from humans. It is concluded that ornithophagous ticks may be infected with CNM and that birds most likely can disperse CNM-infected ticks over large geographical areas.
|
|
| 41. |
|
|
| 42. |
- Marroquin, Ricardo, et al.
(författare)
-
Triatoma ryckmani (Hemiptera: Reduviidae) in the epiphyte Tillandsia xerographica (Bromeliaceae) in the semiarid region of Guatemala
- 2004
-
Ingår i: Journal of Medical Entomology. - 0022-2585. ; 41:3, s. 321-323
-
Tidskriftsartikel (refereegranskat)abstract
- For the first time, the reduviid bug Triatoma ryckmani Zeledón and Ponce (Hemiptera; Reduviidae) was recorded to inhabit the epiphyte Tillandsia xerographica Rohweder (Bromeliaceae) in the semiarid region of Guatemala. These bromeliads grow mainly in drought-resistant trees with rough bark such as Pereskia lychnidiflora (Cactaceae). In our study site, we investigated 30 T. xerographica, and 53 specimens of T. ryckmani were found. Most T. ryckmani (68.5%) were unfed. Ants (Formicidae) were the predominant (92.2%) insect taxon in T. xerographica. Other insects such as Blattidae (3.0%), Reduviidae (T. ryckmani: 2.5%), Blaberidae (2.2%), Gryllidae (0.1%), and Acrididae (0.1%) were recorded in the bromeliads. T. xerographica is illegally commercialized without previous inspection. This may cause accidental introduction of T. ryckmani to houses and to other countries.
|
|
| 43. |
|
|
| 44. |
- Mejlon, Hans, et al.
(författare)
-
Questing behaviour of Ixodes ricinus ticks (Acari: Ixodidae)
- 1997
-
Ingår i: Experimental & applied acarology. - 0168-8162 .- 1572-9702. ; 21:12, s. 747-754
-
Tidskriftsartikel (refereegranskat)abstract
- The vertical distribution in the vegetation of questing Ixodes ricinus ticks was investigated in two different vegetation types ('high' and 'low' vegetation) at two localities in south-central Sweden during 1992-1993 (Torö) and 1995 (Bogesund). Significant correlations were found between the vertical distribution of immature ticks and the height of the vegetation. The greatest mean availabilities of the larvae and nymphs in low vegetation were in the intervals 0-9 and 30-39 cm, respectively. The larval numbers were greatest close to the ground (0-29) in both high and low vegetation. The larval : nymphal ratio, at ground level at localities free of ground vegetation, varied between 8:1 and 32:1. In high vegetation, the greatest mean numbers of nymphal and adult ticks were at height intervals of 50-59 and 60-79 cm, respectively. These ranges are within the estimated height interval (40-100 cm) of the main part of the body surface of their 'preferred' host, the roe deer (Capreolus capreolus). The presence of most questing I. ricinus larvae at ground level would favour the transmission of Borrelia burgdorferi s.l., since this is where the highly reservoir-competent rodents and shrews usually occur.
|
|
| 45. |
- Mejlon, Hans, et al.
(författare)
-
Seasonal prevalence of Borrelia burgdorferi in Ixodes ricinus in different vegetation types in Sweden
- 1993
-
Ingår i: Scandinavian Journal of Infectious Diseases. - : Informa UK Limited. - 0036-5548 .- 1651-1980. ; 25:4, s. 449-456
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this investigation was to estimate the seasonal risk of contracting human Lyme disease in different vegetation types in southern Sweden. Host-seeking Ixodes ricinus ticks (Acari: Ixodidae) were collected with standardized methods during May-September 1988 and March-October 1989 at 10 different sampling sites. Tick abundance was greatest during May-June and August-September. Prevalence of Borrelia burgdorferi infection of the ticks was assessed by phase-contrast microscopy complemented by immunology. Spirochetal infection of tick larvae was not detected. The prevalence of infection among nymphal ticks differed significantly between years and between sampling sites. Infection prevalence was greater in adult females than in nymphs, but was similar in female and male ticks. Among all vegetation types studied, the greatest Lyme disease risk was deemed to be from I. ricinus nymphs during May and September in mixed forest vegetation.
|
|
| 46. |
|
|
| 47. |
- Monroy, Carlota, et al.
(författare)
-
Dispersion and colonization of Triatoma ryckmani (Hemiptera: Reduviidae) in artificial environments in a semiarid region of Chagas disease endemic area in Guatemala
- 2004
-
Ingår i: Acta Tropica. ; 91, s. 145-151
-
Tidskriftsartikel (refereegranskat)abstract
- The colonization capacity and dispersal of sylvatic populations of Triatoma ryckmani Zeledón and Ponce were investigated by means of experimental chicken coops installed within the semiarid region in the Department of El Progreso, Guatemala. In the four artificial habitats a total of 672 T. ryckmani was found as well as two males of T. dimidiata (Latreille). Triatomine densities were not the same in the four chicken coops. From one chicken coop 53.4% (359) of the triatomines were collected. Full colonization, i.e. all stages from egg to adult found at the same time, took place in the fourth month after the first female’s arrival. High dispersal and colonization capacity of T. ryckmani was evident; adult dispersal occurs mainly during the dry and coolest season (November–February). The overall female/male sex ratio was 2:1; more females than males were found throughout the year. Most of the triatomines in the shelter inside the chicken coops were found on the northern (43%; with less heat and sunlight) and eastern side (35%; more windy). This is the first report on the colonization capacity and population dynamics of T. ryckmani in artificial habitats in a Chagas disease endemic area of Central America.
|
|
| 48. |
- Monroy, Maria Carlota, 1954-
(författare)
-
Ecology and Control of Triatomine (Hemiptera: Reduviidae) Vectors of Chagas Disease in Guatemala, Central America
- 2003
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis analyses several factors affecting the control of triatomines in Guatemala. There are three synantropic triatomines in Guatemala, i.e., Rhodnius prolixus, Triatoma dimidiata and T. nitida. Their distibution is mainly at an altitude between 800 and 1500 m a.s.l. R. prolixus and T. nitida have localized but scaterred distibution while T. dimidiata is present in 21 of the 22 departments in the country. Several investigations have shown that R. prolixus could be relatively easily eradicated while T. dimidiata may be more difficult to control, since it is present in domestic, peridomestic and sylvatic environments showing high diversity and a variety of epidemiological characteristics. Based on the incidence of Trypanosma cruzi infection in humans in the distributional areas of the triatomines, R. prolixus appear to be a more competent vector than T. dimidiata. This is despite the fact that these vectors have similar infection rates. Inside houses, R. prolixus and T. dimidiata and in artificial environments, T. ryckmani and T. dimidiata, preferred the northern side of the walls. Therefore, selective application of insecticides should focus on walls and furniture located in the northern part of the house. House improvements reduced the infestation of triatomines, and could be used as a complement to insecticidal spraying. Although T. dimidiata is not an efficient vector its wide distribution, versatility in occupying different habitats and capacity to disperse render this species difficult to control in Central America. Thus, only few months after insecticidal spraying T. dimidiata had reinfested the domestic environments. Morphometic methodology and genetic markers have been developed to differentiate within-species populations of T. dimidiata and T. nitida. Studies on the migration patterns of sylvatic T. dimidiata and T. ryckmani have been performed in order to clarify the colonization patterns. The adults migrate, in particular, in the dry part of the year. This finding may be of help in attempts to control T. dimidiata.
|
|
| 49. |
- Nilsson, Kenneth, et al.
(författare)
-
Characterization of a spotted fever group Rickettsia from Ixodes ricinus ticks in Sweden
- 1997
-
Ingår i: Journal of Clinical Microbiology. - 0095-1137 .- 1098-660X. ; 35:1, s. 243-247
-
Tidskriftsartikel (refereegranskat)abstract
- A spotted fever group rickettsia isolated from the common tick, Ixodes ricinus, was genetically characterized by PCR and genomic sequencing. This study was performed with nymphal and adult ticks collected in southern and central Sweden. I. ricinus is the only North European tick species of medical importance which is regularly collected from humans. No species of the genus Rickettsia has previously been found in Scandinavian ticks, nor has any case of domestic rickettsial infection in humans or animals been reported. According to the nucleotide sequencing, the present Rickettsia sp. belongs to the spotted fever group of rickettsiae. Ticks are the most common arthropod reservoirs and vectors of the rickettsiae of this group. Among 748 ticks investigated, 13 (1.7%) were positive for a Rickettsia sp. Borrelia burgdorferi was detected in 52 (7%) of the ticks, a prevalence similar to or somewhat lower than that previously been recorded in other Swedish studies. There was no evidence of ehrlichial or chlamydial DNA in these ticks. The Rickettsia sp. was further characterized by 16S ribosomal DNA (rDNA) sequencing and restriction fragment length polymorphism (RFLP). The 16S rDNA sequencing resulted in a sequence identical to that described for Rickettsia helvetica, but the pattern obtained with RFLP of the citrate synthetase gene diverged from previously known patterns. The rickettsial agent of one tick which was positive by PCR was confirmed by transmission electron microscopy. The morphology of this rickettsia was similar to that of the spotted fever and typhus group rickettsiae. This represents the first documented isolate of a Rickettsia sp. from Swedish ticks.
|
|
| 50. |
- Oliveira, E., et al.
(författare)
-
High Levels of Hybridization between Molecular Forms of Anopheles gambiae from Guinea Bissau
- 2008
-
Ingår i: Journal of medical entomology. - 0022-2585 .- 1938-2928. ; 45:6, s. 1057-1063
-
Tidskriftsartikel (refereegranskat)abstract
- In the malaria vector Anopheles gambiae Giles sensu stricto, two molecular forms denoted M and S are considered units of incipient speciation within this species. Very low hybrid frequencies and significant genetic differentiation have been found in sympatric M- and S-form populations, We studied the molecular form composition and the degree of genetic differentiation at 15 microsatellites in two samples of An. gambiae collected ill two consecutive years from Bissau, Guinea Bissau. High frequencies of M/S hybrids (19-24%) were found in this area. Coincidently, very low levels of genetic differentiation were detected between forms when analysis involved microsatellites mapped at chromosome-3 (mean F-st 0.000-0.002). The single exception was the X-linked AGXH678, for which high differentiation was measured (F-st 0.158-0.301). This locus maps near the centromere of chromosome X, a low recombination region in which selection is likely to promote divergence between M and S forms. These results strongly suggest that the degree of isolation between M and S forms, considered the units of incipient speciation within An. gambiae, is not homogenous throughout the species distribution range.
|
|
