Volume 17, Number 1—January 2011
Dispatch
Tick-borne Encephalitis Virus in Wild Rodents in Winter, Finland, 2008–2009
Table
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) | |||||
2008 | |||||
Myodes glareolus vole | 63 | 1§ | 0 | 1 (1.6) | 2 (3.2) |
Sorex caecutiens shrew | 4 | 0 | 0 | 0 | 0 |
S. araneus shrew | 7 | 0 | 0 | 0 | 0 |
2009 | |||||
M. glareolus vole | 17 | 4§ | 2 | 5 (29.4) | 4 (23.5) |
S. araneus shrew |
3 |
0 |
1 |
1 (33.3) |
0 |
Isosaari (TBEV-Eur) | |||||
2008 | |||||
Microtus agrestis vole | 71 | 3¶ | 2 | 4 (5.6) | 0 |
S. araneus shrew | 7 | 0 | 0 | 0 | 0 |
2009 | |||||
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.