title: Surveillance of endemic foci of tick-borne encephalitis in Finland 1995-2013: evidence of emergence of new foci.
abstract: The geographical risk areas for tick-borne encephalitis (TBE) in Finland remained the same until the beginning of the 21st century, but a considerable geographical expansion has been observed in the past 10 years. In order to support public health measures, the present study describes the number of laboratory-confirmed TBE cases and laboratory tests conducted and the associated trends by hospital district, with a particular emphasis on the suspected geographical risk areas. An additional investigation was conducted on 1,957 clinical serum samples throughout the country taken from patients with neurological symptoms to screen for undiagnosed TBE cases. This study identified new TBE foci in Finland, reflecting the spread of the disease into new areas. Even in the most endemic municipalities, transmission of TBE to humans occurred in very specific and often small foci. The number of antibody tests for TBE virus more than doubled (an increase by 105%) between 2007 and 2013. Analysis of the number of tests also revealed areas in which the awareness of clinicians may be suboptimal at present. However, it appears that underdiagnosis of neuroinvasive TBE is not common.
authors.affiliation: Departments of Virology and Veterinary Biosciences, University of Helsinki, Helsinki, Finland.
authors.forename: Elina
authors.initials: E
authors.lastname: Tonteri
authors.forename: Satu
authors.initials: S
authors.lastname: Kurkela
authors.forename: Suvi
authors.initials: S
authors.lastname: Timonen
authors.forename: Tytti
authors.initials: T
authors.lastname: Manni
authors.forename: Tytti
authors.initials: T
authors.lastname: Vuorinen
authors.forename: Markku
authors.initials: M
authors.lastname: Kuusi
authors.forename: Olli
authors.initials: O
authors.lastname: Vapalahti
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D000914:Antibodies, Viral / Q000097:blood*; D002648:Child; D002675:Child, Preschool; D004669:Encephalitis Viruses, Tick-Borne / Q000276:immunology*; D004675:Encephalitis, Tick-Borne / Q000453:epidemiology*; D019353:Endemic Diseases; D062665:Epidemiological Monitoring; D005260:Female; D005387:Finland / Q000453:epidemiology; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D018884:Ixodes / Q000821:virology*; D008297:Male; D008875:Middle Aged; D011159:Population Surveillance; D012367:RNA, Viral / Q000235:genetics / Q000302:isolation & purification; D012306:Risk; D055815:Young Adult
chemical_list: D000914:Antibodies, Viral; D012367:RNA, Viral
keywords: Finland; Kumlinge disease; emerging foci; surveillance system for TBE; tick-borne encephalitis; Åland