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  • 1.
    Aase, Audun
    et al.
    Norwegian Institute Public Heatlh, Norway.
    Hajdusek, Ondrej
    Academic Science Czech Republic, Czech Republic.
    Oines, Oivind
    Norwegian Vet Institute, Norway.
    Quarsten, Hanne
    Sorlandet Hospital Health Enterprise, Norway.
    Wilhelmsson, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Herstad, Tove K.
    Norwegian Institute Public Heatlh, Norway.
    Kjelland, Vivian
    University of Agder, Norway; Sorlandet Hospital Health Enterprise, Norway.
    Sima, Radek
    Academic Science Czech Republic, Czech Republic.
    Jalovecka, Marie
    Academic Science Czech Republic, Czech Republic.
    Lindgren, Per-Eric
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences. County Hospital Ryhov, Sweden.
    Aaberge, Ingeborg S.
    Norwegian Institute Public Heatlh, Norway.
    Validate or falsify: Lessons learned from a microscopy method claimed to be useful for detecting Borrelia and Babesia organisms in human blood2016In: INFECTIOUS DISEASES, ISSN 2374-4235, Vol. 48, no 6, p. 411-419Article in journal (Refereed)
    Abstract [en]

    Background A modified microscopy protocol (the LM-method) was used to demonstrate what was interpreted as Borrelia spirochetes and later also Babesia sp., in peripheral blood from patients. The method gained much publicity, but was not validated prior to publication, which became the purpose of this study using appropriate scientific methodology, including a control group. Methods Blood from 21 patients previously interpreted as positive for Borrelia and/or Babesia infection by the LM-method and 41 healthy controls without known history of tick bite were collected, blinded and analysed for these pathogens by microscopy in two laboratories by the LM-method and conventional method, respectively, by PCR methods in five laboratories and by serology in one laboratory. Results Microscopy by the LM-method identified structures claimed to be Borrelia- and/or Babesia in 66% of the blood samples of the patient group and in 85% in the healthy control group. Microscopy by the conventional method for Babesia only did not identify Babesia in any samples. PCR analysis detected Borrelia DNA in one sample of the patient group and in eight samples of the control group; whereas Babesia DNA was not detected in any of the blood samples using molecular methods. Conclusions The structures interpreted as Borrelia and Babesia by the LM-method could not be verified by PCR. The method was, thus, falsified. This study underlines the importance of doing proper test validation before new or modified assays are introduced.

  • 2.
    Dessau, Ram B
    et al.
    Slagelse Hospital, Slagelse, Denmark.
    Fryland, Linda
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Wilhelmsson, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Ekerfelt, Christina
    Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences.
    Nyman, Dag
    Åland University, Mariehamn, Finlad.
    Forsberg, Pia
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Infectious Diseases.
    Lindgren, Per-Eric
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Study of a Cohort of 1,886 Persons To Determine Changes in Antibody Reactivity to Borrelia burgdorferi 3 Months after a Tick Bite2015In: Clinical and Vaccine Immunology, ISSN 1556-6811, E-ISSN 1556-679X, Vol. 22, no 7, p. 823-827Article in journal (Refereed)
    Abstract [en]

    Lyme borreliosis is a tick-borne disease caused by the bacterium Borrelia burgdorferi. The most frequent clinical manifestation is a rash called erythema migrans. Changes in antibody reactivity to B. burgdorferi 3 months after a tick bite are measured using enzyme-linked immunosorbent assays (ELISAs). One assay is based on native purified flagellum antigen (IgG), and the other assay is based on a recombinant antigen called C6 (IgG or IgM). Paired samples were taken at the time of a tick bite and 3 months later from 1,886 persons in Sweden and the Åland Islands, Finland. The seroconversion or relative change is defined by dividing the measurement units from the second sample by those from the first sample. The threshold for the minimum level of significant change was defined at the 2.5% level to represent the random error level. The thresholds were a 2.7-fold rise for the flagellar IgG assay and a 1.8-fold rise for the C6 assay. Of 1,886 persons, 102/101 (5.4%) had a significant rise in antibody reactivity in the flagellar assay or the C6 assay. Among 40 cases with a diagnosis of Lyme borreliosis, the sensitivities corresponding to a rise in antibodies were 33% and 50% for the flagellar antigen and the C6 antigen, respectively. Graphical methods to display the antibody response and to choose thresholds for a rise in relative antibody reactivity are shown and discussed. In conclusion, 5.4% of people with tick bites showed a rise in Borrelia-specific antibodies above the 2.5% threshold in either ELISA but only 40 (2.1%) developed clinical Lyme borreliosis.

  • 3.
    Fryland, Linda
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Clinical and Experimental Medicine, Clinical Immunology.
    Forsberg, Pia
    Linköping University, Department of Clinical and Experimental Medicine, Infectious Diseases. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Medicine, Department of Infectious Diseases in Östergötland.
    Sandin, Linnea
    Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
    Wilhelmsson, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
    Lindblom, Pontus
    Linköping University, Department of Clinical and Experimental Medicine, Medical Microbiology. Linköping University, Faculty of Health Sciences.
    Nyman, Dag
    Aland Borrelia Grp.
    Lindgren, Per-Eric
    Linköping University, Department of Clinical and Experimental Medicine, Medical Microbiology. Linköping University, Faculty of Health Sciences.
    Ernerudh, Jan
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Immunology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Laboratory Medicine, Department of Clinical Immunology and Transfusion Medicine.
    Ekerfelt, Christina
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Clinical and Experimental Medicine, Clinical Immunology.
    Biomarkers in blood a few days after a bite by a Borrelia burgdorferi infected tick:: Asymptomatic Borrelia burgdorferi-infected subjects show higher Th1-associated response compared with subjects who later develop Lyme borreliosis2012Manuscript (preprint) (Other academic)
    Abstract [en]

    The clinical outcome following infection with Borrelia (B.) burgdorferi sensu lato (s.l.) differs between individuals, ranging from asymptomatic infection to Lyme borreliosis (LB) with persistent symptoms post-treatment. Previous studies in mice and humans have generated the hypothesis that a successful outcome of B. burgdorferi s.l. infection is associated with an early strong pro-inflammatory T helper (Th)1-like immune response. The aim of this study was to assess the early course of events in B. burgdorferi s.l.-associated inflammation by screening for possible early immune biomarkers in peripheral blood from newly tick-bitten persons. The study subjects bitten by B. burgdorferi s.l.-infected ticks were divided into (1) those later developing clinical LB, (2) those who developed anti-B. burgdorferi s.l. antibodies but not clinical LB, (3) those who neither developed antibodies nor clinical LB. A fourth group consisted of bitten study subjects without development of antibodies or clinical LB. Two sets of samples, both comprising all four groups, were collected in order to repeat the analyses and confirm the data. Sera or plasma collected a few days after the tick bite were analysed for 18 biomarkers (IL-1β, IL-6, CXCL8/IL-8, IL-12p70, IL-17A, IL-27, TNF, CCL18, CCL20, CCL22, CXCL1, CXCL9, CXCL10, CXCL11, calprotectin, MMP-3, MMP-8, MMP-9) by multiplex bead assay and ELISA. In the first set of samples, the neutrophil activation marker calprotectin was increased in subjects who developed clinical LB compared with subjects who developed antibodies against B. burgdorferi s.l. but did not develop LB. However, the finding could not be confirmed in the second set of samples, thus the study failed to identify an early prognostic marker for development of clinical LB. Interestingly, both sets of samples showed increases in two different Th1-associated markers, CXCL10 and IL-12p70, respectively, in subjects who following a bite by a B. burgdorferi s.l.-infected tick developed antibodies against B. burgdorferi s.l. but did not develop LB compared with subjects who developed clinical LB, thus supporting the hypothesis of an early strong Th1-response being important for optimal resolution of B. burgdorferi s.l. infection.

  • 4.
    Fryland, Linda
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Immunology. Linköping University, Faculty of Health Sciences.
    Wilhelmsson, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Medical Microbiology. Linköping University, Faculty of Health Sciences.
    Lindgren, Per-Eric
    Linköping University, Department of Clinical and Experimental Medicine, Medical Microbiology. Linköping University, Faculty of Health Sciences.
    Nyman, Dag
    Aland Borrelia Grp.
    Ekerfelt, Christina
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Immunology. Linköping University, Faculty of Health Sciences.
    Forsberg, Pia
    Linköping University, Department of Clinical and Experimental Medicine, Infectious Diseases. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Medicine, Department of Infectious Diseases in Östergötland.
    Low risk of developing Borrelia burgdorferi infection in the south-east of Sweden after being bitten by a Borrelia burgdorferi-infected tick2011In: INTERNATIONAL JOURNAL OF INFECTIOUS DISEASES, ISSN 1201-9712, Vol. 15, no 3, p. E174-E181Article in journal (Refereed)
    Abstract [en]

    Objectives: The risk of developing Lyme borreliosis (LB) from Borrelia burgdorferi sensu lato (Bb)-infected ticks in Sweden is largely unknown. In the current study, we investigated the prevalence of Bb in ticks that had bitten humans and the risk of developing LB from Bb-infected ticks. Methods: Health questionnaires, blood samples, and ticks were collected from 394 tick-bitten study subjects in the County of Ostergotland, Sweden, at the time of the tick bite. Questionnaires and blood samples were also collected 3 months later. Ticks were screened for Bb DNA with PCR, while sera were analyzed for antibodies against Bb using two ELISA assays. Seroconversion, i.e., an at least two-fold increase in anti-Bb antibodies after 3 months, was confirmed using a Strip-Immunoassay. Results: Seventy-five of 397 ticks collected from the study subjects were determined to be Bb-positive. Sixty-four of the tick-bitten subjects had been bitten by Bb-infected ticks. Four of them showed seroconversion and were therefore considered to have an active Bb infection. None of these four subjects had sought health care due to symptoms, but one reported symptoms. Conclusions: Our data suggest that the risk of developing LB after being bitten by a Bb-infected tick is low, and asymptomatic Bb infections appear to be more frequent than symptomatic infections.

  • 5.
    Grankvist, Anna
    et al.
    University of Gothenburg, Sweden; Sahlgrens University Hospital, Sweden.
    Labbe Sandelin, Lisa
    Kalmar County Hospital, Sweden; Uppsala University, Sweden.
    Andersson, Jennie
    University of Gothenburg, Sweden; Sahlgrens University Hospital, Sweden.
    Fryland, Linda
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Wilhelmsson, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Lindgren, Per-Eric
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences. County Hospital Ryhov, Sweden.
    Forsberg, Pia
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Infectious Diseases.
    Wenneras, Christine
    University of Gothenburg, Sweden; Sahlgrens University Hospital, Sweden.
    Infections with Candidatus Neoehrlichia mikurensis and Cytokine Responses in 2 Persons Bitten by Ticks, Sweden2015In: Emerging Infectious Diseases, ISSN 1080-6040, E-ISSN 1080-6059, Vol. 21, no 8, p. 1462-1465Article in journal (Refereed)
    Abstract [en]

    The prevalence of Candidatus Neoehrlichia mikurensis infection was determined in 102 persons bitten by ticks in Sweden. Two infected women had erythematous rashes; 1 was co-infected with a Borrelia sp., and the other showed seroconversion for Anaplasma phagocytophilum. Both patients had increased levels of Neoehrlichia DNA and serum cytokines for several months.

  • 6.
    Henningsson, Anna J
    et al.
    Ryhov County Hospital, Jönköping.
    Wilhelmsson, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Gyllemark, Paula
    Ryhov County Hospital, Jönköping.
    Kozak Ljunggren, Monika
    Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Department of Clinical and Experimental Medicine, Division of Cell Biology.
    Matussek, Andreas
    Ryhov County Hospital, Jönköping.
    Nyman, Dag
    Ryhov County Hospital, Jönköping.
    Ekerfelt, Christina
    Bimelix Biomedical Laboratory, Mariehamn, Åland, Finland .
    Lindgren, Per-Eric
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Ryhov County Hospital, Jönköping.
    Forsberg, Pia
    Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Infectious Diseases. Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine.
    Low risk of seroconversion or clinical disease in humans after a bite by an Anaplasma phagocytophilum-infected tick2015In: Ticks and Tick-borne Diseases, ISSN 1877-959X, E-ISSN 1877-9603, Vol. 6, no 6, p. 787-792Article in journal (Refereed)
    Abstract [en]

    The risk of contracting human granulocytic anaplasmosis (HGA) after a tick bite is mainly unknown. In this study we investigated the clinical and serological response in 30 humans bitten by ticks positive for Anaplasma phagocytophilum (Group A), 30 humans bitten by Borrelia burgdorferi sensu lato (s.l.)-positive ticks (Group B), and 30 humans bitten by ticks negative for both A. phagocytophilum and B. burgdorferi s.l. (Group C). Ticks, blood samples and questionnaires were collected from tick-bitten humans at 34 primary healthcare centres in Sweden and in the Åland Islands, Finland, at the time of the tick bite and after three months. A total of 2553 ticks detached from humans in 2007-2009 were analyzed by polymerase chain reaction, and 31 (1.2%) were positive for A. phagocytophilum, 556 (21.8%) were positive for B. burgdorferi s.l., and eight (0.3%) were co-infected by A. phagocytophilum and B. burgdorferi s.l. The overall prevalence of Anaplasma IgG antibodies in the included participants (n=90) was 17%, and there was no significant difference between the groups A-C. Only one of the participants (in Group C) showed a four-fold increase of IgG antibodies against A. phagocytophilum at the three-month follow-up, but reported no symptoms. The frequency of reported symptoms did not differ between groups A-C, and was unrelated to the findings of A. phagocytophilum and B. burgdorferi s.l. in the detached ticks. We conclude that the risk for HGA or asymptomatic seroconversion after a tick bite in Sweden or in the Åland Islands is low, even if the tick is infected by A. phagocytophilum.

  • 7.
    Labbe Sandelin, Lisa
    et al.
    Uppsala University, Sweden; Kalmar County Hospital, Sweden.
    Tolf, Conny
    Linnaeus University, Sweden.
    Larsson, Sara
    Linnaeus University, Sweden.
    Wilhelmsson, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Salaneck, Erik
    Uppsala University, Sweden.
    Jaenson, Thomas G. T.
    Uppsala University, Sweden.
    Lindgren, Per-Eric
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Olsen, Bjorn
    Uppsala University, Sweden.
    Waldenstrom, Jonas
    Linnaeus University, Sweden.
    Candidatus Neoehrlichia mikurensis in Ticks from Migrating Birds in Sweden2015In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 10, no 7, p. e0133250-Article in journal (Refereed)
    Abstract [en]

    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.

  • 8.
    Lindblom, Pontus
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Clinical and Experimental Medicine.
    Wilhelmsson, Peter
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Clinical and Experimental Medicine.
    Fryland, Linda
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Clinical and Experimental Medicine.
    Matussek, Andreas
    County Hospital Ryhov, Jönköping.
    Haglund, Mats
    Kalmar County hospital.
    Sjöwall, Johanna
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Clinical and Experimental Medicine. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Infectious Diseases.
    Vene, Sirkka
    Swedish Institute for Communicable Disease Control, Stockholm.
    Nyman, Dag
    Åland Central Hospital, Åland, Finland.
    Forsberg, Pia
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Clinical and Experimental Medicine. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Infectious Diseases.
    Lindgren, Per-Eric
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Clinical and Experimental Medicine.
    Determining factors for successful vaccination against tick-borne encephalitis virus in older individuals2014Manuscript (preprint) (Other academic)
    Abstract [en]

    We performed a cross-sectional study including 533 persons (median age 61) from the highly TBE endemic Åland Islands in the archipelago between Sweden and Finland. Blood samples, questionnaires and vaccination records were obtained from all study participants. The aim was to investigate if there was any association between TBEV antibody titer and 14 healthrelated factors: [age, gender, number of vaccine doses (0-5), time since last vaccine dose, previous TBE disease, vaccination against other flaviviruses, ≥2 tick-bites during the previous 3 months, pet-ownership, asthma, smoking, allergy, diabetes, medication, and previous tumor]. Measurement of TBEV IgG antibodies was performed using two commercial ELISA assays (Enzygnost and Immunozym), and a third in-house rapid fluorescent focus inhibition test was used to measure TBEV neutralizing antibodies. The age of the person and the number of vaccine doses were the two most important factors determining successful vaccination. The response to each vaccine dose declined linearly with increased age. A 35 year age difference corresponds to a vaccine dose increment from 3 to 4 to achieve the same response. Participants receiving medication and participants previously vaccinated against other flaviviruses had lower TBEV antibody titers on average, while those with self-reported asthma had higher titers. By comparing the 3 serological assays we show that the Enzygnost and Immunozym assay differ due to choice of cutoffs, but not in overall accuracy.

  • 9.
    Lindblom, Pontus
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences.
    Wilhelmsson, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences.
    Fryland, Linda
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences.
    Matussek, Andreas
    County Hospital Ryhov, Sweden .
    Haglund, Mats
    County Hospital Kalmar, Sweden .
    Sjöwall, Johanna
    Linköping University, Department of Clinical and Experimental Medicine, Division of Clinical Sciences. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Infectious Diseases.
    Vene, Sirkka
    Public Health Agency Sweden, Stockholm.
    Nyman, Dag
    Aland Central Hospital, Finland .
    Forsberg, Pia
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Infectious Diseases.
    Lindgren, Per-Eric
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences.
    Factors Determining Immunological Response to Vaccination against Tick-Borne Encephalitis Virus in Older Individuals2014In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, no 6, p. e0100860-Article in journal (Refereed)
    Abstract [en]

    We performed a cross-sectional study including 533 individuals (median age 61) from the highly TBE endemic A land Islands in the archipelago between Sweden and Finland. Blood samples, questionnaires and vaccination records were obtained from all study participants. The aim was to investigate if there was any association between TBEV antibody titer and 12 health-related factors. Measurement of TBEV IgG antibodies was performed using two commercial ELISA assays (Enzygnost and Immunozym), and a third in-house rapid fluorescent focus inhibition test was used to measure TBEV neutralizing antibodies. The age of the individual and the number of vaccine doses were the two most important factors determining the immunological response to vaccination. The response to each vaccine dose declined linearly with increased age. A 35 year age difference corresponds to a vaccine dose increment from 3 to 4 to achieve the same immunological response. Participants previously vaccinated against other flaviviruses had lower odds of being seropositive for neutralizing TBEV antibodies on average, while participants with self-reported asthma had higher odds of being seropositive. By comparing the 3 serological assays we show that the Enzygnost and Immunozym assay differ due to choice of cutoffs, but not in overall accuracy.

  • 10.
    Lindblom, Pontus
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences.
    Wilhelmsson, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences.
    Fryland, Linda
    Linköping University, Department of Clinical and Experimental Medicine, Division of Inflammation Medicine. Linköping University, Faculty of Health Sciences.
    Sjowall, Johanna
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Infectious Diseases.
    Haglund, Mats
    Kalmar County hospital.
    Matussek, Andreas
    County Hospital Ryhov, Jönköping.
    Ernerudh, Jan
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Immunology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Diagnostics, Department of Clinical Immunology and Transfusion Medicine.
    Vene, Sirkka
    Swedish Institute for Communicable Disease Control, Stockholm.
    Nyman, Dag
    Åland Central Hospital, Åland, Finland.
    Andreassen, Åshild
    Norwegian Institute of Public Health, Olso, Norway.
    Forsberg, Pia
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Infectious Diseases.
    Lindgren, Per-Eric
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences.
    Tick-borne encephalitis virus in ticks detached from humans and follow-up of serological and clinical response.2014In: Ticks and Tick Borne Diseases, ISSN 1877-959X, Vol. 5, no 1, p. 21-28Article in journal (Refereed)
    Abstract [en]

    The risk of tick-borne encephalitis virus (TBEV) infection after a tick bite remains largely unknown. To address this, we investigated the presence of TBEV in ticks detached from humans in an attempt to relate viral copy number, TBEV subtype, and tick feeding time with the serological and clinical response of the tick-bitten participants. Ticks, blood samples, and questionnaires were collected from tick-bitten humans at 34 primary health care centers in Sweden and in the Aland Islands (Finland). A total of 2167 ticks was received from 1886 persons in 2008-2009. Using a multiplex quantitative real-time PCR, 5 TBEV-infected ticks were found (overall prevalence 0.23%, copy range <4 X 10(2)-7.7 X 10(6) per tick). One unvaccinated person bitten by a tick containing 7.7 x 10(6) TBEV copies experienced symptoms. Another unvaccinated person bitten by a tick containing 1.8 x 10(3) TBEV copies developed neither symptoms nor TBEV antibodies. The remaining 3 persons were protected by vaccination. In contrast, despite lack of TBEV in the detached ticks, 2 persons developed antibodies against TBEV, one of whom reported symptoms. Overall, a low risk of TBEV infection was observed, and too few persons got bitten by TBEV-infected ticks to draw certain conclusions regarding the clinical outcome in relation to the duration of the blood meal and virus copy number. However, this study indicates that an antibody response may develop without clinical symptoms, that a bite by an infected tick not always leads to an antibody response or clinical symptoms, and a possible correlation between virus load and tick feeding time. (C) 2013 Elsevier GmbH. All rights reserved.

  • 11.
    Wilhelmsson, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences.
    A STING from a Tick: Epidemiology, Ecology and Clinical Aspects of Lyme Borreliosis2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Lyme borreliosis (LB) is the most common tick-borne disease in the Northern Hemisphere and the number of LB cases is increasing. The infection is caused by spirochetes belonging to the Borrelia burgdorferi sensu lato complex, and is, in Europe, transmitted to humans by Ixodes ricinus ticks.

    To gain a deeper knowledge of the interactions between ticks, humans and Borrelia bacteria, we investigated temporal differences in exposure to tick bites in different parts of Sweden and the Åland Islands, Finland during the years 2008 and 2009. We also investigated the site of tick attachment on the human body and the time it takes for a person to detected and remove such ticks. Furthermore, the distribution of Borrelia species and the number of Borrelia cells in the ticks were investigated. Sera taken from the tick-bitten persons at study inclusion were analyzed for the presence of Borrelia antibodies. Three months later, the clinical outcome and the serological response of the tick-bitten persons were investigated. A total of 2154 I. ricinus ticks and 1546 participants were included in the studies.

    Participants were exposed to tick bites between April and November, but temporal and spatial differences in exposure to ticks was found. The majority of the tick bites were caused by nymphs (70%) and most tick bites took place on the legs (50%). The site of tick attachment on the body as well as the age and gender of the participant influenced how soon a tick was detected. The majority of participants removed “their” ticks later than 24 hours of attachment. Of all ticks, 26% was Borrelia-infected, but the prevalence varied between the life stages of the tick and between the studied areas. Six species of the B. burgdorferi sensu lato complex and one Borrelia species that may cause tick-borne relapsing fever were detected. Adult ticks that had fed more than 36 hours contained a lower number of Borrelia cells than adult ticks that had fed less than 36 hours. The seroprevalence among the participants varied between genders as well as between the studied areas. Of all participants, 2% was diagnosed with LB and 2.5% seroconverted without an LB diagnose. A correlation between seroconversion and duration time of tick attachment was found, but the number of Borrelia cells in the tick, did not explain the risk of infection for the bitten person.

    A deeper knowledge and a better understanding of the interactions between ticks, humans and Borrelia bacteria may contribute reducing the risk for tick bites and the risk of developing LB after a tick bite.

    List of papers
    1. Ixodes ricinus ticks removed from humans in Northern Europe: seasonal pattern of infestation, attachment sites and duration of feeding
    Open this publication in new window or tab >>Ixodes ricinus ticks removed from humans in Northern Europe: seasonal pattern of infestation, attachment sites and duration of feeding
    Show others...
    2013 (English)In: Parasites & Vectors, ISSN 1756-3305, E-ISSN 1756-3305, Vol. 6, no 362Article in journal (Refereed) Published
    Abstract [en]

    BACKGROUND:

    The common tick Ixodes ricinus is the main vector in Europe of the tick-borne encephalitis virus and of several species of the Borrelia burgdorferi sensu lato complex, which are the etiological agents of Lyme borreliosis. The risk to contract bites of I. ricinus is dependent on many factors including the behaviour of both ticks and people. The tick's site of attachment on the human body and the duration of tick attachment may be of clinical importance. Data on I. ricinus ticks, which were found attached to the skin of people, were analysed regarding potentially stage-specific differences in location of attachment sites, duration of tick attachment (= feeding duration), seasonal and geographical distribution of tick infestation in relation to age and gender of the tick-infested hosts.

    METHODS:

    During 2008-2009, 1770 tick-bitten persons from Sweden and the Åland Islands removed 2110 I. ricinus ticks. Participants provided information about the date of tick detection and location on their body of each attached tick. Ticks were identified to species and developmental stage. The feeding duration of each nymph and adult female tick was microscopically estimated based on the scutal and the coxal index.

    RESULTS:

    In 2008, participants were tick-bitten from mid-May to mid-October and in 2009 from early April to early November. The infestation pattern of the nymphs was bimodal whereas that of the adult female ticks was unimodal with a peak in late summer. Tick attachment site on the human body was associated with stage of the tick and gender of the human host. Site of attachment seemed to influence the duration of tick feeding. Overall, 63% of nymphs and adult female ticks were detected and removed more than 24 hours after attachment. Older persons, compared to younger ones, and men, compared to women, removed "their" ticks after a longer period of tick attachment.

    CONCLUSIONS:

    The infestation behaviour of the different tick stages concerning where on the host's body the ticks generally will attach and when such ticks generally will be detected and removed in relation to host age and gender, should be of value for the development of prophylactic methods against tick infestation and to provide relevant advice to people on how to avoid or reduce the risk of tick infestation.

    Place, publisher, year, edition, pages
    BioMed Central, 2013
    Keywords
    Ixodes ricinus; Tick infestation; Tick bite; Attachment site; Feeding behaviour; Feeding duration; Host-seeking behaviour; Seasonal activity; Sweden; Åland
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-103499 (URN)10.1186/1756-3305-6-362 (DOI)000330064200001 ()24360096 (PubMedID)
    Available from: 2014-01-20 Created: 2014-01-20 Last updated: 2017-12-06Bibliographically approved
    2. Prevalence and Diversity of Borrelia Species in Ticks That Have Bitten Humans in Sweden
    Open this publication in new window or tab >>Prevalence and Diversity of Borrelia Species in Ticks That Have Bitten Humans in Sweden
    Show others...
    2010 (English)In: JOURNAL OF CLINICAL MICROBIOLOGY, ISSN 0095-1137, Vol. 48, no 11, p. 4169-4176Article in journal (Refereed) Published
    Abstract [en]

    Members of the genus Borrelia are among the most common infectious agents causing tick-borne disease in humans worldwide. Here, we developed a Light Upon eXtension (LUX) real-time PCR assay that can detect and quantify Borrelia species in ticks that have fed on humans, and we applied the assay to 399 such ticks. Borrelia PCR-positive ticks were identified to species level by sequencing the products of conventional PCR performed using Borrelia group-specific primers. There was a 19% prevalence of Borrelia spp. in the detached ticks, and the number of spirochetes per Borrelia PCR-positive tick ranged from 2.0 x 10(2) to 4.9 x 10(5), with a median of 7.8 x 10(3) spirochetes. Adult ticks had a significantly larger number of spirochetes, with a median of 8.4 x 10(4) compared to the median of nymphs of 4.4 x 10(4). Adult ticks also exhibited a higher prevalence of Borrelia (33%) than nymphs (14%). Among the identified species, Borrelia afzelii was found to predominate (61%) and was followed by B. garinii (23%), B. valaisiana (13%), B. burgdorferi sensu stricto (1%), B. lusitaniae (1%), and B. miyamotoi-like (1%). Also, 3% of the ticks were coinfected with multiple strains of B. afzelii. Notably, this is the first report of B. lusitaniae being detected in ticks in Sweden. Our LUX real-time PCR assay proved to be more sensitive than a corresponding TaqMan assay. In conclusion, the novel LUX real-time PCR method is a rapid and sensitive tool for detection and quantification of Borrelia spp. in ticks.

    Place, publisher, year, edition, pages
    American Society for Microbiology, 2010
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-62152 (URN)10.1128/JCM.01061-10 (DOI)000283588500049 ()
    Note
    Original Publication: Peter Wilhelmsson, Linda Fryland, Stefan Börjesson, Johan Nordgren, Sven Bergström, Jan Ernerudh, Pia Forsberg and Per-Eric Lindgren, Prevalence and Diversity of Borrelia Species in Ticks That Have Bitten Humans in Sweden, 2010, JOURNAL OF CLINICAL MICROBIOLOGY, (48), 11, 4169-4176. http://dx.doi.org/10.1128/JCM.01061-10 Copyright: American Society for Microbiology http://www.asm.org/ Available from: 2010-11-19 Created: 2010-11-19 Last updated: 2014-03-25
    3. Prevalence, Diversity, and Load of Borrelia species in Ticks That Have Fed on Humans in Regions of Sweden and Åland Islands, Finland with Different Lyme Borreliosis Incidences
    Open this publication in new window or tab >>Prevalence, Diversity, and Load of Borrelia species in Ticks That Have Fed on Humans in Regions of Sweden and Åland Islands, Finland with Different Lyme Borreliosis Incidences
    Show others...
    2013 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 8, no 11, p. e81433-Article in journal (Refereed) Published
    Abstract [en]

    The incidence of Lyme borreliosis (LB) in a region may reflect the prevalence of Borrelia in the tick population. Our aim was to investigate if regions with different LB incidences can be distinguished by studying the prevalence and diversity of Borrelia species in their respective tick populations. The Borrelia load in a feeding tick increases with the duration of feeding, which may facilitate a transmission of Borrelia Spirochetes from tick to host. Therefore, we also wanted to investigate how the Borrelia load in ticks that have fed on humans varies with the duration of tick feeding. During 2008 and 2009, ticks that had bitten humans were collected from four regions of Sweden and Finland, regions with expected differences in LB incidence. The duration of tick feeding was estimated and Borrelia were detected and quantified by a quantitative PCR assay followed by species determination. Out of the 2,154 Ixodes ricinus ticks analyzed, 26% were infected with Borrelia and seven species were identified. B. spielmanii was detected for the first time in the regions. The tick populations collected from the four regions exhibited only minor differences in both prevalence and diversity of Borrelia species, indicating that these variables alone cannot explain the regions different LB incidences. The number of Borrelia cells in the infected ticks ranged from fewer than ten to more than a million. We also found a lower number of Borrelia cells in adult female ticks that had fed for more than 36 hours, compared to the number of Borrelia cells found in adult female ticks that had fed for less than 36 hours.

    Place, publisher, year, edition, pages
    Public Library of Science, 2013
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-102779 (URN)10.1371/journal.pone.0081433 (DOI)000327539800130 ()
    Note

    Funding Agencies|Medical Research Council of South-East Sweden|FORSS-8967FORSS-12573FORSS-29021FORSS-86911|Swedish Research Council (Medicine)|2011-345|County Council of Ostergotland||Wilhelm and Else Stockmanns Foundation||Angstromlands Kuturstiftelse||EU Interreg IV A|167226|

    Available from: 2014-01-07 Created: 2013-12-26 Last updated: 2017-12-06
    4. A prospective study on the incidence of Borrelia infection after a tick bite in Sweden and on the Åland Islands, Finland (2008-2009)
    Open this publication in new window or tab >>A prospective study on the incidence of Borrelia infection after a tick bite in Sweden and on the Åland Islands, Finland (2008-2009)
    Show others...
    2016 (English)In: Ticks and Tick-borne Diseases, ISSN 1877-959X, E-ISSN 1877-9603, Vol. 7, no 1, p. 71-79Article in journal (Refereed) Published
    Abstract [en]

    Lyme borreliosis (LB) is a common and increasing tick-borne disease in Europe. The risk of acquiring a Borrelia infection after a tick bite is not fully known. Therefore, we investigated the incidence of Borrelia infection after a tick bite and if the Borrelia load and/or the duration of tick-feeding influenced the risk of infection. During 2008-2009, ticks and blood samples were collected from 1546 tick-bitten persons from Sweden and the Åland Islands, Finland. Follow-up blood samples were taken three months after the tick bite. The duration of tick feeding was microscopically estimated and Borrelia was detected and quantified in ticks by real-time PCR. Anti-Borrelia antibodies were detected in sera using ELISA assays and immunoblot.

    Even though 28 % of the participants were bitten by a Borrelia-positive tick, only 7.5% (32/428) of them developed a Borrelia infection, half of them LB. All who seroconverted removed “their” ticks significantly later than those who did not. The Borrelia load in the ticks did not explain the risk of seroconversion. Regional as well as gender differences in the Borrelia seroprevalence were found. The risk of developing a Borrelia infection after a bite by a Borrelia-infected tick is small but increases with the duration of tick feeding.

    Place, publisher, year, edition, pages
    Elsevier, 2016
    Keywords
    Borrelia burgdorferi sensu lato; tick bite; incidence of infection; Lyme borreliosis; asymptomatic infection; bacterial load; tick-feeding.
    National Category
    Infectious Medicine
    Identifiers
    urn:nbn:se:liu:diva-105475 (URN)10.1016/j.ttbdis.2015.08.009 (DOI)000366953400012 ()
    Note

    Funding agencies: Swedish Research Council Branch of Medicine [K2008-58X-14631-06-3]; Medical Research Council of South-East Sweden [FORSS-8967, FORSS-12573, FORSS-29021, FORSS-86911]; EU Interreg IV A project ScandTick [167226]; County Council of Ostergotland [LIO-56191];

    Available from: 2014-03-25 Created: 2014-03-25 Last updated: 2017-05-03Bibliographically approved
  • 12.
    Wilhelmsson, Peter
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
    Fryland, Linda
    Linköping University, Department of Clinical and Experimental Medicine. Linköping University, Faculty of Health Sciences.
    Börjesson, Stefan
    Linköping University, Department of Clinical and Experimental Medicine, Medical Microbiology. Linköping University, Faculty of Health Sciences.
    Nordgren, Johan
    Linköping University, Department of Clinical and Experimental Medicine, Medical Microbiology. Linköping University, Faculty of Health Sciences.
    Bergström, Sven
    Ernerudh, Jan
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Immunology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Diagnostics, Department of Clinical Immunology and Transfusion Medicine.
    Forsberg, Pia
    Linköping University, Department of Clinical and Experimental Medicine, Infectious Diseases. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Infectious Diseases.
    Lindgren, Per-Eric
    Linköping University, Department of Clinical and Experimental Medicine, Medical Microbiology. Linköping University, Faculty of Health Sciences.
    Erratum: Prevalence and Diversity of Borrelia Species in Ticks That Have Bitten Humans in Sweden (vol 48, pg 4169, 2010)2011In: Journal of Clinical Microbiology, ISSN 0095-1137, E-ISSN 1098-660X, Vol. 49, no 1, p. 481-481Article in journal (Other academic)
    Abstract [en]

    n/a

  • 13.
    Wilhelmsson, Peter
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
    Fryland, Linda
    Linköping University, Department of Clinical and Experimental Medicine. Linköping University, Faculty of Health Sciences.
    Börjesson, Stefan
    Linköping University, Department of Clinical and Experimental Medicine, Medical Microbiology. Linköping University, Faculty of Health Sciences.
    Nordgren, Johan
    Linköping University, Department of Clinical and Experimental Medicine, Medical Microbiology. Linköping University, Faculty of Health Sciences.
    Bergström, Sven
    Umeå University.
    Ernerudh, Jan
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Immunology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Diagnostics, Department of Clinical Immunology and Transfusion Medicine.
    Forsberg, Pia
    Linköping University, Department of Clinical and Experimental Medicine, Infectious Diseases. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Centre, Department of Infectious Diseases in Östergötland.
    Lindgren, Per-Eric
    Linköping University, Department of Clinical and Experimental Medicine, Medical Microbiology. Linköping University, Faculty of Health Sciences.
    Prevalence and Diversity of Borrelia Species in Ticks That Have Bitten Humans in Sweden2010In: JOURNAL OF CLINICAL MICROBIOLOGY, ISSN 0095-1137, Vol. 48, no 11, p. 4169-4176Article in journal (Refereed)
    Abstract [en]

    Members of the genus Borrelia are among the most common infectious agents causing tick-borne disease in humans worldwide. Here, we developed a Light Upon eXtension (LUX) real-time PCR assay that can detect and quantify Borrelia species in ticks that have fed on humans, and we applied the assay to 399 such ticks. Borrelia PCR-positive ticks were identified to species level by sequencing the products of conventional PCR performed using Borrelia group-specific primers. There was a 19% prevalence of Borrelia spp. in the detached ticks, and the number of spirochetes per Borrelia PCR-positive tick ranged from 2.0 x 10(2) to 4.9 x 10(5), with a median of 7.8 x 10(3) spirochetes. Adult ticks had a significantly larger number of spirochetes, with a median of 8.4 x 10(4) compared to the median of nymphs of 4.4 x 10(4). Adult ticks also exhibited a higher prevalence of Borrelia (33%) than nymphs (14%). Among the identified species, Borrelia afzelii was found to predominate (61%) and was followed by B. garinii (23%), B. valaisiana (13%), B. burgdorferi sensu stricto (1%), B. lusitaniae (1%), and B. miyamotoi-like (1%). Also, 3% of the ticks were coinfected with multiple strains of B. afzelii. Notably, this is the first report of B. lusitaniae being detected in ticks in Sweden. Our LUX real-time PCR assay proved to be more sensitive than a corresponding TaqMan assay. In conclusion, the novel LUX real-time PCR method is a rapid and sensitive tool for detection and quantification of Borrelia spp. in ticks.

  • 14.
    Wilhelmsson, Peter
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences.
    Fryland, Linda
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences.
    Lindblom, Pontus
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences.
    Sjöwall, Johanna
    Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Infectious Diseases. Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine.
    Ahlm, Clas
    Division of Infectious Diseases, Department of Clinical Microbiology, Umeå University, Umeå, Sweden.
    Berglund, Johan
    School of Health Science, Blekinge Institute of Technology, Karlskrona, Sweden.
    Haglund, Mats
    Department of Infectious Diseases, Kalmar County Hospital, Kalmar, Sweden.
    Henningsson, Anna J
    Department of Clinical Microbiology, Division of Medical Services, Ryhov County Hospital, Jönkoping, Sweden.
    Nolskog, Peter
    Department of Communicable Disease Control and Prevention, Region Västra Götaland, Skaraborg Hospital, Skövde, Sweden.
    Nordberg, Marika
    The Åland Group for Borrelia Research, Mariehamn, Åland, Finland.
    Nyberg, Clara
    The Åland Group for Borrelia Research, Mariehamn, Åland, Finland.
    Ornstein, Katharina
    Department of Internal Medicine, Hässleholm Hospital, Hässleholm, Sweden/Department of Clinical Sciences, Lund University, Lund, Sweden.
    Nyman, Dag
    The Åland Group for Borrelia Research, Mariehamn, Åland, Finland.
    Ekerfelt, Christina
    Linköping University, Department of Clinical and Experimental Medicine, Division of Inflammation Medicine. Linköping University, Faculty of Health Sciences.
    Forsberg, Pia
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Infectious Diseases.
    Lindgren, Per-Eric
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences.
    A prospective study on the incidence of Borrelia infection after a tick bite in Sweden and on the Åland Islands, Finland (2008-2009)2016In: Ticks and Tick-borne Diseases, ISSN 1877-959X, E-ISSN 1877-9603, Vol. 7, no 1, p. 71-79Article in journal (Refereed)
    Abstract [en]

    Lyme borreliosis (LB) is a common and increasing tick-borne disease in Europe. The risk of acquiring a Borrelia infection after a tick bite is not fully known. Therefore, we investigated the incidence of Borrelia infection after a tick bite and if the Borrelia load and/or the duration of tick-feeding influenced the risk of infection. During 2008-2009, ticks and blood samples were collected from 1546 tick-bitten persons from Sweden and the Åland Islands, Finland. Follow-up blood samples were taken three months after the tick bite. The duration of tick feeding was microscopically estimated and Borrelia was detected and quantified in ticks by real-time PCR. Anti-Borrelia antibodies were detected in sera using ELISA assays and immunoblot.

    Even though 28 % of the participants were bitten by a Borrelia-positive tick, only 7.5% (32/428) of them developed a Borrelia infection, half of them LB. All who seroconverted removed “their” ticks significantly later than those who did not. The Borrelia load in the ticks did not explain the risk of seroconversion. Regional as well as gender differences in the Borrelia seroprevalence were found. The risk of developing a Borrelia infection after a bite by a Borrelia-infected tick is small but increases with the duration of tick feeding.

  • 15.
    Wilhelmsson, Peter
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences.
    Lindblom, Pontus
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences.
    Fryland, Linda
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences.
    Ernerudh, Jan
    Linköping University, Department of Clinical and Experimental Medicine, Division of Inflammation Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Diagnostics, Department of Clinical Immunology and Transfusion Medicine.
    Forsberg, Pia
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Infectious Diseases.
    Lindgren, Per-Eric
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences.
    Prevalence, Diversity, and Load of Borrelia species in Ticks That Have Fed on Humans in Regions of Sweden and Åland Islands, Finland with Different Lyme Borreliosis Incidences2013In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 8, no 11, p. e81433-Article in journal (Refereed)
    Abstract [en]

    The incidence of Lyme borreliosis (LB) in a region may reflect the prevalence of Borrelia in the tick population. Our aim was to investigate if regions with different LB incidences can be distinguished by studying the prevalence and diversity of Borrelia species in their respective tick populations. The Borrelia load in a feeding tick increases with the duration of feeding, which may facilitate a transmission of Borrelia Spirochetes from tick to host. Therefore, we also wanted to investigate how the Borrelia load in ticks that have fed on humans varies with the duration of tick feeding. During 2008 and 2009, ticks that had bitten humans were collected from four regions of Sweden and Finland, regions with expected differences in LB incidence. The duration of tick feeding was estimated and Borrelia were detected and quantified by a quantitative PCR assay followed by species determination. Out of the 2,154 Ixodes ricinus ticks analyzed, 26% were infected with Borrelia and seven species were identified. B. spielmanii was detected for the first time in the regions. The tick populations collected from the four regions exhibited only minor differences in both prevalence and diversity of Borrelia species, indicating that these variables alone cannot explain the regions different LB incidences. The number of Borrelia cells in the infected ticks ranged from fewer than ten to more than a million. We also found a lower number of Borrelia cells in adult female ticks that had fed for more than 36 hours, compared to the number of Borrelia cells found in adult female ticks that had fed for less than 36 hours.

  • 16.
    Wilhelmsson, Peter
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences.
    Lindblom, Pontus
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences.
    Fryland, Linda
    Linköping University, Department of Clinical and Experimental Medicine, Infectious Diseases. Linköping University, Faculty of Health Sciences.
    Nyman, Dag
    Jaenson, Thomas GT
    Uppsala University, Sweden .
    Forsberg, Pia
    Linköping University, Department of Clinical and Experimental Medicine, Infectious Diseases. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Infectious Diseases.
    Lindgren, Per-Eric
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences. Ryhov County Hospital, Jönköping, Sweden .
    Ixodes ricinus ticks removed from humans in Northern Europe: seasonal pattern of infestation, attachment sites and duration of feeding2013In: Parasites & Vectors, ISSN 1756-3305, E-ISSN 1756-3305, Vol. 6, no 362Article in journal (Refereed)
    Abstract [en]

    BACKGROUND:

    The common tick Ixodes ricinus is the main vector in Europe of the tick-borne encephalitis virus and of several species of the Borrelia burgdorferi sensu lato complex, which are the etiological agents of Lyme borreliosis. The risk to contract bites of I. ricinus is dependent on many factors including the behaviour of both ticks and people. The tick's site of attachment on the human body and the duration of tick attachment may be of clinical importance. Data on I. ricinus ticks, which were found attached to the skin of people, were analysed regarding potentially stage-specific differences in location of attachment sites, duration of tick attachment (= feeding duration), seasonal and geographical distribution of tick infestation in relation to age and gender of the tick-infested hosts.

    METHODS:

    During 2008-2009, 1770 tick-bitten persons from Sweden and the Åland Islands removed 2110 I. ricinus ticks. Participants provided information about the date of tick detection and location on their body of each attached tick. Ticks were identified to species and developmental stage. The feeding duration of each nymph and adult female tick was microscopically estimated based on the scutal and the coxal index.

    RESULTS:

    In 2008, participants were tick-bitten from mid-May to mid-October and in 2009 from early April to early November. The infestation pattern of the nymphs was bimodal whereas that of the adult female ticks was unimodal with a peak in late summer. Tick attachment site on the human body was associated with stage of the tick and gender of the human host. Site of attachment seemed to influence the duration of tick feeding. Overall, 63% of nymphs and adult female ticks were detected and removed more than 24 hours after attachment. Older persons, compared to younger ones, and men, compared to women, removed "their" ticks after a longer period of tick attachment.

    CONCLUSIONS:

    The infestation behaviour of the different tick stages concerning where on the host's body the ticks generally will attach and when such ticks generally will be detected and removed in relation to host age and gender, should be of value for the development of prophylactic methods against tick infestation and to provide relevant advice to people on how to avoid or reduce the risk of tick infestation.

  • 17.
    Wilhelmsson, Peter
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Lindgren, Per Eric
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Detection of a novel Lyme borreliosis pathogen.2016In: Lancet. Infectious diseases (Print), ISSN 1473-3099, E-ISSN 1474-4457, Vol. 16, no 5, p. 511-512Article in journal (Other academic)
1 - 17 of 17
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