Small mammal trapping and sampling
Small mammals were trapped from 2012 to 2014 five times per year, in
mid-April and in each first week of June, July, September and October.
The trapping grid consisted of 196 live-traps (14 X 14 Uggland special
nr. 3, Grahnab, Sweden) set at 15 m intervals, covering a total area of
3.2 ha. For each session, traps were set for three consecutive nights
and baited with carrots and sunflower seeds. Trapped rodents were
individually marked with a transponder (Vétérissimo Mini RWI-I, Vethica,
France). Blood samples were taken once per session through the
retro-orbital sinus. Species, body mass, sex and tick presence were
recorded and then the animals were released at the point of capture. We
used the minimum value of weight observed during a second capture
session to define the threshold value below which an individual was
considered juvenile. Accordingly, individuals weighting less than 14 g
for M. glareolus and 16 g for A. flavicollis were
considered juveniles. From April 2012 to July 2013, all the ticks found
on rodents were collected. In June and July 2012, given the high number
of small rodents captured, although all the animals were subject to
blood sampling and examined for tick presence, we only counted and
collected the ticks of a number of randomly-chosen animals infested by
ticks. All the ticks and blood samples were kept at +4°C until brought
back to the laboratory. There, the blood clot was gently detached from
the bottom of the Eppendorf tube before being centrifuged at 5000 rpm
for 5 min and the serum obtained was stored at -20°C until tested for
the presence of TBEV antibodies. Larvae were identified at genus level
and nymphs/adults at species level based on their morphology using
appropriate keys and descriptions (Pérez‐Eid, 2007). All the ticks were
washed in 70% ethanol, rinsed twice in distilled water, dried, and
stored at -80°C until tested for TBEV