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A Serosurvey of Tick-Borne Encephalitis Virus in Sweden: Different Populations and Geographical Locations

Svensson, Joel LU ; Christiansen, Claus B and Persson, Kristina E M LU (2021) In Vector-Borne and Zoonotic Diseases 21(8). p.614-619
Abstract
Abstract
Background: New risk areas for tick-borne encephalitis (TBE) are emerging and the spread of disease and vaccine coverage is unclear in Sweden. We wanted to study the prevalence and levels of TBE-virus (TBEV) antibodies in southern Sweden, and to investigate whether there were individuals with undiagnosed TBE.

Materials and Methods: Two cohorts of sera were collected: One group of anonymous individuals in rural areas (AIRA) in Skåne and one group of volunteers who often got tick-bites (tick-bitten individuals [TBI]). An enzyme-linked immunosorbent assay for TBEV IgM and IgG was performed, as well as a TBEV neutralization test (NT) in selected individuals.

Results: In the AIRA group, there was an IgG... (More)
Abstract
Background: New risk areas for tick-borne encephalitis (TBE) are emerging and the spread of disease and vaccine coverage is unclear in Sweden. We wanted to study the prevalence and levels of TBE-virus (TBEV) antibodies in southern Sweden, and to investigate whether there were individuals with undiagnosed TBE.

Materials and Methods: Two cohorts of sera were collected: One group of anonymous individuals in rural areas (AIRA) in Skåne and one group of volunteers who often got tick-bites (tick-bitten individuals [TBI]). An enzyme-linked immunosorbent assay for TBEV IgM and IgG was performed, as well as a TBEV neutralization test (NT) in selected individuals.

Results: In the AIRA group, there was an IgG seropositivity of 5.3%. There were individuals with high antibody levels both in areas previously considered as risk areas (Bromölla and Knislinge), as well as in another area (Tyringe). In the TBI group, 45% of the individuals were vaccinated according to the questionnaires and IgG seropositivity was 28%. A lower seroprevalence and levels of antibodies were seen in the middle-aged group (50–69 years) compared with younger or elderly study participants. A positive NT revealed several individuals with suspected undiagnosed episodes of TBE.

Conclusion: Subclinical or misdiagnosed cases have probably occurred in Skåne. Middle-aged individuals had lower levels of IgG, which could indicate either less tick exposure or a lower vaccine response. Less than half of the TBI were vaccinated, an indication that more information about the disease and vaccine might be needed. We conclude that the study motivates an increased awareness of TBEV in the region. (Less)
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author
; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Vector-Borne and Zoonotic Diseases
volume
21
issue
8
pages
614 - 619
publisher
Mary Ann Liebert, Inc.
external identifiers
  • pmid:34028305
  • scopus:85112413371
ISSN
1557-7759
DOI
10.1089/vbz.2020.2763
language
English
LU publication?
yes
id
f603b41a-c07f-416d-993b-0373efb93cf9
date added to LUP
2021-05-30 15:41:54
date last changed
2025-04-04 14:49:06
@article{f603b41a-c07f-416d-993b-0373efb93cf9,
  abstract     = {{Abstract<br/>Background: New risk areas for tick-borne encephalitis (TBE) are emerging and the spread of disease and vaccine coverage is unclear in Sweden. We wanted to study the prevalence and levels of TBE-virus (TBEV) antibodies in southern Sweden, and to investigate whether there were individuals with undiagnosed TBE.<br/><br/>Materials and Methods: Two cohorts of sera were collected: One group of anonymous individuals in rural areas (AIRA) in Skåne and one group of volunteers who often got tick-bites (tick-bitten individuals [TBI]). An enzyme-linked immunosorbent assay for TBEV IgM and IgG was performed, as well as a TBEV neutralization test (NT) in selected individuals.<br/><br/>Results: In the AIRA group, there was an IgG seropositivity of 5.3%. There were individuals with high antibody levels both in areas previously considered as risk areas (Bromölla and Knislinge), as well as in another area (Tyringe). In the TBI group, 45% of the individuals were vaccinated according to the questionnaires and IgG seropositivity was 28%. A lower seroprevalence and levels of antibodies were seen in the middle-aged group (50–69 years) compared with younger or elderly study participants. A positive NT revealed several individuals with suspected undiagnosed episodes of TBE.<br/><br/>Conclusion: Subclinical or misdiagnosed cases have probably occurred in Skåne. Middle-aged individuals had lower levels of IgG, which could indicate either less tick exposure or a lower vaccine response. Less than half of the TBI were vaccinated, an indication that more information about the disease and vaccine might be needed. We conclude that the study motivates an increased awareness of TBEV in the region.}},
  author       = {{Svensson, Joel and Christiansen, Claus B and Persson, Kristina E M}},
  issn         = {{1557-7759}},
  language     = {{eng}},
  month        = {{05}},
  number       = {{8}},
  pages        = {{614--619}},
  publisher    = {{Mary Ann Liebert, Inc.}},
  series       = {{Vector-Borne and Zoonotic Diseases}},
  title        = {{A Serosurvey of Tick-Borne Encephalitis Virus in Sweden: Different Populations and Geographical Locations}},
  url          = {{http://dx.doi.org/10.1089/vbz.2020.2763}},
  doi          = {{10.1089/vbz.2020.2763}},
  volume       = {{21}},
  year         = {{2021}},
}