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Volume 17, Number 1—January 2011

Tick-borne Encephalitis Virus in Wild Rodents in Winter, Finland, 2008–2009

Elina Tonteri, Anu E. JääskeläinenComments to Author , Tapani Tikkakoski, Liina Voutilainen, Jukka Niemimaa, Heikki Henttonen, Antti Vaheri, and Olli Vapalahti
Author affiliations: Author affiliations: University of Helsinki, Helsinki, Finland (E. Tonteri, A.E. Jääskeläinen, L. Voutilainen, A. Vaheri, O. Vapalahti); Karolinska Institutet, Solna, Sweden (E. Tonteri); Keski-Pohjanmaa Central Hospital, Kokkola, Finland (T. Tikkakoski); Finnish Forest Research Institute, Vantaa, Finland (L. Voutilainen, J. Niemimaa, H. Henttonen); Hospital District of Helsinki and Uusimaa, Helsinki (O. Vapalahti)

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Small mammals trapped during 2 subsequent winters (2008 and 2009) in TBEV-Eur– and TBEV-Sib–endemic areas, Finland*

Location (virus subtype), year, and mammal species No. animals trapped No. RNA positive by real-time PCR
No. (%) antibody positive†
Brain Organ pool/spleen‡ Total (%)
Kokkola (TBEV-Sib)
Myodes glareolus vole 63 0 1 (1.6) 2 (3.2)
Sorex caecutiens shrew 4 0 0 0 0
S. araneus shrew 7 0 0 0 0
M. glareolus vole 17 2 5 (29.4) 4 (23.5)
S. araneus shrew
1 (33.3)
Isosaari (TBEV-Eur)
Microtus agrestis vole 71 2 4 (5.6) 0
S. araneus shrew 7 0 0 0 0
M. agrestis vole 24 13 0 13 (54.2) 2 (8.3)
S. araneus shrew 6 0 0 0 0

*TBEV, tick-borne encephalitis virus; TBEV-Eur, European subtype of TBEV; TVEV-Sib, Siberian subtype of TBEV.
†Blood samples, diluted ≈1:10 in phosphate-buffered saline, were screened by immunofluorescence assay with TBEV-infected Vero E6 cells as antigen.
‡For animals collected in 2008, organ pool of lungs, spleen, and liver were screened; for animals collected in 2009, only spleen was screened.
§Three brain samples positive for TBEV RNA by real-time reverse transcription–PCR (RT-PCR) (1 in 2008 and 2 in 2009) were also positive for the TBEV nonstructural protein (NS) 5 gene by nested RT-PCR.
¶Two brain samples positive for TBEV RNA by RT-PCR were also positive for the TBEV NS5 gene by nested RT-PCR.

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Page created: June 30, 2011
Page updated: June 30, 2011
Page reviewed: June 30, 2011
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