RESEARCH Open Access
Se ological e idence o ick-bo ne
encephali is i us in ec ion in moose and
dee in Finland: sen inels o i us
ci cula ion
Elina Ton e i
1*
, Pikka Jokelainen
2,3,4
, Juho Ma ala
5
, Jy ki Pusenius
5
and Olli Vapalah i
1,2,6
Abs ac
Backg ound: The incidence o ick-bo ne encephali is (TBE) in humans has inc eased in Finland, and he disease
has eme ged in new oci. These oci ha e been in es iga ed o de e mine he ci cula ing i us sub ype, he ick
hos species and he ecological pa ame e s, bu coun ywide epidemiological in o ma ion on he dis ibu ion o
TBEV has been limi ed.
Me hods: In his s udy, we sc eened se a om hun e -ha es ed wild ce ids o he p esence o an ibodies agains
ick-bo ne encephali is i us (TBEV) wi h a hemagglu ina ion inhibi ion es . The posi i e esul s we e con i med by
a neu alisa ion assay.
Resul s: Nine (0.74 %) o 1213 moose, one (0.74 %) o 135 whi e- ailed dee , and none o he 17 oe dee we e
ound se oposi i e o TBEV. A close geog aphical cong uence be ween se oposi i e ce ids and ecen ly epo ed
human TBE cases was obse ed: nine o he en se oposi i e animals we e om known endemic a eas.
Conclusions: Ou esul s con i m he local ci cula ion o TBEV in se e al known endemic a eas. One se oposi i e
moose had been sho in an a ea whe e human TBE cases ha e no been epo ed, sugges ing a possible new
ocus. Moose appea o be a use ul sen inel animal o he p esence o TBEV in he aiga egion.
Keywo ds: Moose, Roe dee , Se ology, Tick-bo ne encephali is, Whi e- ailed dee , Zoonosis
Backg ound
Tick-bo ne encephali is i us (TBEV) is a zoono ic a bo-
i us. In 1991–2010, i caused up o 12,733 annual e-
po ed human cases o ick-bo ne encephali is (TBE) in
Eu ope [1]. The e a e h ee known gene ic sub ypes o
he i us: Eu opean, Sibe ian and Fa -Eas e n [2]. The
sub ypes di e in hei endemic egions and ecological
p e e ences, and possibly in hei pa hogenici y [3].
The i us is main ained in an enzoo ic cycle o icks,
which a e ec o s and hos s o he i us, and hei e -
eb a e hos s. Non- i emic ansmission (NVT) o TBEV
be ween icks co- eeding on small e eb a es is consid-
e ed impo an o he main enance o he i us [4]. Due
o he complex ecology o TBEV, i s geog aphical dis i-
bu ion is mul i ocal [5].
La ge mammals a e seconda y hos s o TBEV as hey
suppo he ick popula ions by p o iding blood meals.
The NVT compe ence o la ge mammals is con o e sial
and la gely unknown: goa s a e no NVT-compe en ,
whe eas he NVT po en ial o oe dee (Cap eolus
cap eolus), which can be hea ily in es ed by co- eeding
la ae and nymphs, has no been s udied [6–10]. Ne e -
heless, oe dee and ed dee (Ce us elaphus) appea
o be key hos s o icks and he eby impo an o
TBEV main enance [8–10]. In Sweden, he inc ease in
TBE incidence has been associa ed wi h changes in ce -
id popula ions, especially oe dee popula ions [11].
TBE is usually subclinical in middle-sized and la ge
mammals [12]. Howe e , in Sweden, a moose (Alces
alces) cal wi h se e e beha io al abno mali ies and
* Co espondence: [email p o ec ed]
1
Depa men o Vi ology, Uni e si y o Helsinki, Facul y o Medicine, Helsinki,
Finland
Full lis o au ho in o ma ion is a ailable a he end o he a icle
© 2016 Ton e i e al. Open Access This a icle is dis ibu ed unde he e ms o he C ea i e Commons A ibu ion 4.0
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Ton e i e al. Pa asi es & Vec o s (2016) 9:54
DOI 10.1186/s13071-016-1335-6
subsequen ly diagnosed encephali is was ound o be
TBEV-posi i e [13].
Finland is a he no he n bounda y o he cu en dis-
ibu ion a ea o TBEV [14]. Two sub ypes o he i us,
Eu opean and Sibe ian, as well as he wo main hos ick
species, Ixodes icinus and I.pe sulca us, ha e been de-
sc ibed [15].Be ween 2007 and 2014, a o al o 273 hu-
man TBE cases we e epo ed in Finland [16, 17]. The
cases occu ed mainly in known endemic a eas, whe e
human TBE cases ha e been diagnosed o decades, and
whe e TBEV an ibodies we e de ec ed in ca le al eady
in he 1960s [16, 18]. The incidence o human TBE has
inc eased, and he disease has eme ged in new oci [16].
Bank ole (Myodes gla eolus) appea s o be he domin-
an small mammal in he s udied TBEV oci in Finland
in he bo eal aiga egion [14, 19]. La ge and middle-
sized mammalian species suppo ing he local main en-
ance o TBEV ha e no been in es iga ed.
The e a e h ee wild ce id species wi h subs an ial pop-
ula ions in Finland. Since he1970's, he moose popula ion
has comp ised 60,000 o 200,000 indi iduals ha a e
e enly dis ibu ed ac oss he coun y [20, 21]. The whi e-
ailed dee (Odocoileus i ginianus) popula ion has 40,000
o 50,000 indi iduals, ha inhabi mainly sou h-wes e n
Finland [22]. The oe dee popula ion o 10,000 o 20,000
indi iduals is dis ibu ed spa sely ac oss he coun y, wi h
he highes numbe s in he sou h-wes [23].
In his s udy, we sc eened se a o hese h ee wild ce -
id species o TBEV-speci ic an ibodies o es ima e he
se op e alence and o de e mine he geog aphical dis i-
bu ion o TBEV in Finland. We discuss he sui abili y o
moose as a sen inel animal o he p esence o TBEV
and as an indica o o local isk o human TBE
in ec ions.
Me hods
E hics s a emen
No animals we e killed o he pu pose o his s udy.
The animals we e sampled pos mo em, a e hey had
been legally killed by hun e s. The samples we e s o ed,
coded, and all da a we e ea ed con iden ially.
S udy design and sampling
The se um bank was collec ed du ing he hun ing sea-
son o 2008–2009, p ima ily o a na ionwide c oss-
sec ional se ological s udy on Toxoplasma gondii [24].
The sample is a con enience sample, and he sampling
was no a ge ed o TBEV oci. Al oge he 2917 sam-
pling packages we e dis ibu ed o he game manage-
men dis ic s, which subsequen ly dis ibu ed hem o
he hun e s. Each package included wo plas ic VACU-
ETTE® Se um Clo Ac i a o blood sample ubes
(G eine Bio-One GmbH, K emsmüns e , Aus ia) and a
ques ionnai e co e ing he game managemen dis ic ,
and species, sex and age g oup o he animal sampled.
All he animals included in he s udy we e legally
hun ed o human consump ion. The olun a ily pa ici-
pa ing hun e s collec ed he samples om he animals
and illed ou he ques ionnai e o each animal. The
pa icipa ion a e was 47 %. Samples we e sen by mail
and a i ed a he labo a o y wi hin 4 days o sampling,
be ween Sep embe 15 h 2008 and Feb ua y 2nd 2009.
Upon a i al, he samples we e coded, and se a we e
sepa a ed by cen i uga ion, di ided in o aliquo s and
s o ed a - 20 °C un il analyzed. Only he code numbe
o each sample was known by he pe sons pe o ming
he es s.
A o al o 1371 ce id samples we e included in his
s udy. The samples om 1213 moose o igina ed om all
15 game managemen dis ic s. The dee samples, om
135 whi e- ailed dee and 17 oe dee , had been col-
lec ed only om he sou h-wes e n dis ic s whe e hese
ce ids a e he mos nume ous. The species o six sam-
ples was unspeci ied.
Se ological me hods
Fo he se ological analysis o he p esence o an i-
TBEV an ibodies, we used an in-house hemagglu ina ion
inhibi ion (HI) es [25] using he ollowing wo- old di-
lu ions: 1:10, 1:20, 1:40, 1:80, 1:160, 1:320, 1:640. Ti e s
we e de e mined acco ding o hese dilu ions, howe e ,
in cases whe e he las dilu ion showed pa ial inhibi ion
o hemagglu ina ion, he i e was de e mined as he
alue be ween he las clea dilu ion and he bo de line
dilu ion and is p esen ed in Table 1 by showing bo h he
lowe and highe dilu ions. Posi i e esul s we e u he
con i med by a apid ocus- o ming inhibi ion es o
neu alizing an ibodies using Swedish Eu opean sub ype
s ain 93–783 [25]. The es was pe o med in dilu ions
1:5 and 1:20. The samples ha es ed posi i e in he HI
es and posi i e o bo de line in he neu alisa ion es
we e de ined as se oposi i e. In addi ion, he samples
we e sc eened wi h in-house HI es s o he p esence o
an ibodies agains wo o he la i i uses ha could cause
c oss- eac i e an ibody esponses: Wes Nile i us
(WNV), which has no been ound in Finland, and Lam-
mi i us (LAMV) which has been ound in mosqui oes in
Finland [26].
S a is ical analyses
Two-by- wo ables and es s a is ics we e used o p e-
limina y compa isons [27]. Logis ical eg ession analyses
wi h S a a 11.0 (S a aCo p, College S a ion, Texas, US)
we e used o e alua e e ec s o a ailable explana o y
a iables (game managemen dis ic , sex, species, age
g oup) on he ou come a iable, TBEV-se oposi i i y.
Ton e i e al. Pa asi es & Vec o s (2016) 9:54 Page 2 o 8
Resul s
Al oge he 28 samples es ed posi i e o an i-TBEV
an ibodies wi h he HI es (Table 1), and i e s anged
om 15 o 640. These se a we e u he subjec o con-
i ma o y analysis by he TBEV neu alisa ion es . Ten
samples showed posi i e (<10/20) o bo de line esul
wi h dilu ions 1:5 (NT 5) o 1:20 (NT 20) and we e hus
de ined as se oposi i e (Table 1). The samples showing
TBEV-speci ic an ibodies by he neu alisa ion es had
highe HI- i e s han hose samples ha es ed posi i e
only on he HI es . The se oposi i e animals consis ed
o i e adul male moose, wo adul emale moose, wo
young male moose, and one adul male whi e- ailed
dee .
The en se oposi i e animals we e om six di e en
game managemen dis ic s, and hei geog aphical dis-
ibu ion appea ed o co ela e closely wi h he known
human in ec ion si es: nine se oposi i e animals o igi-
na ed om a eas whe e human cases ha e been de-
sc ibed (Fig. 1). The se op e alences in moose and
Table 1 Basic da a and se ological esul s o he wild ce ids hun ed in 2008–2009 in Finland ha es ed se oposi i e in he
sc eening o an ibodies agains ick-bo ne encephali is i us by hemagglu ina ion inhibi ion es
Indi idual Species Age Sex Dis ic
a
HI Neu alisa ion HI HI
TBEV TBEV WNV LAMV
NT 5 NT 20 NT esul
1. moose adul M 8 640 20/20 20/20 neg neg 20–40
2. moose adul M 1 160–320 0/20 6/20 pos <10 neg
3. moose cal M 8 160–320 9/20 17/20 pos neg neg
4. moose adul M 5 80–160 0/20 20/20 pos neg neg
5. moose nd. F 8 80 4/20 15/20 pos neg neg
6. moose adul M 1 80 0/20 10/20 pos neg neg
7. moose adul M 13 80 20/20 20/20 neg neg neg
8. moose adul M 3 80 2/20 17/20 pos neg neg
9. moose cal M 14 40–80 10/20 20/20 pos/neg neg neg
10. moose adul M 7 40 0/20 13/20 pos neg 20–40
11. moose cal F 13 40 20/20 20/20 neg neg neg
12. moose adul M 14 <40 20/20 20/20 neg neg neg
13. moose adul F 10 20–40 20/20 20/20 neg neg neg
14. moose cal M 7 20 20/20 20/20 neg neg neg
15. dee
b
adul M 1 20 12/20 20/20 pos/neg neg neg
16. moose cal M 4 20 20/20 20/20 neg neg neg
17. moose cal F 3 20 16/20 20/20 neg neg 10
18. moose adul F 12 20 18/20 20/20 neg neg neg
19. moose adul M 5 <20 20/20 20/20 neg neg neg
20. moose adul F 1 10–20 20/20 20/20 neg neg neg
21. moose adul M 8 10–20 14/20 20/20 pos/neg 10 10–20
22. moose adul M 1 10–20 20/20 20/20 neg neg neg
23. moose adul M 7 10–20 17/20 20/20 neg neg neg
24. moose cal M 3 10–20 20/20 20/20 neg neg neg
25. moose adul F 3 10–20 20/20 20/20 neg neg neg
26. moose adul M 1 10–20 20/20 20/20 neg neg neg
27. moose adul F 8 10–20 16/20 20/20 neg neg neg
a
Dis ic s p esen ed in Fig. 1. The game adminis a i e dis ic s a e desc ibed acco ding o The Finnish Wildli e Agency
b
Whi e- ailed dee
NT 5 neu alisa ion es , dilu ion 1:5
NT 20, neu alisa ion es , dilu ion 1:20
HI hemagglu ina ion inhibi ion es
TBEV ick-bo ne encephali is i us
WNV Wes -Nile i us
LAMV Lammi i us
Ton e i e al. Pa asi es & Vec o s (2016) 9:54 Page 3 o 8
whi e- ailed dee we e 0.74 %, and he se op e alences
did no di e signi ican ly be ween he species, sexes
and age g oups (Table 2). Logis ic eg ession analyses e-
ealed no mul i a iable associa ion.
None o he samples es ed posi i e o WNV. Th ee
o ou samples ha we e weakly posi i e o LAMV,
showed lowe i e s o his i us han o TBEV in he
hemagglu ina ion es (Table 1). One o he LAMV-
posi i e samples showed a a he high hemagglu ina ion
i e , bu his sample was s ill also posi i e o TBEV ac-
co ding o he TBEV neu alisa ion es (Table 1).
Discussion
P esence o an i-TBEV-an ibodies in moose has been
p e iously in es iga ed appa en ly only in Sweden in
1962 and mo e ecen ly in No way [13, 28]. In he
15
13
7
9
14
5
3
12
11
6
10
2
4
1
8
30°E21°E
68°N
65°N
62°N
Ce id samples:
Pos_Hl + neu
Neg
HI high, neu neg.
HI low, neu neg.
Human pos 2007-08
Human pos 2009-13
62 neg.
A c ic Ci cle
Fig. 1 Geog aphical dis ibu ion o he hun ing loca ions o he es ed wild ce ids, he animals de ined as se oposi i e o an ibodies agains
ick-bo ne encephali is i us, and he cases o human ick-bo ne encephali is in Finland. Da a on hun ing loca ion we e a ailable o 79.2 % o he
animals. The numbe s 1–15 e e o he game managemen dis ic s
Ton e i e al. Pa asi es & Vec o s (2016) 9:54 Page 4 o 8
Swedish s udy, he se op e alence among 75 indi iduals
was 44 %, which is almos six y imes highe han he
Finnish es ima e ob ained in his s udy. The neu alisa-
ion es was used in bo h s udies, bu he esul s a e no
compa able because mos o he animals included in he
Swedish s udy had been sho in a known endemic a ea,
whe eas his s udy co e ed he whole o Finland excep
o he highly endemic Åland islands. In he No wegian
s udy, which used a comme cial ELISA me hod, he
p e alence was 52 %, bu he sample size (N= 27) was
small and he geog aphical ange limi ed.
In his s udy, we used an in-house HI es as he p i-
ma y sc eening es . Because la i i uses cause c oss-
eac ions in se ological analyses, he posi i e esul s we e
con i med by a labou -in ensi e, bu mo e speci ic neu-
alisa ion es . To exclude some known c oss- eac i e
la i i uses, we es ed he TBEV-posi i e samples (in he
HI es ) also o Wes Nile i us (WNV) and Lammi-
i us (LAMV). Low i e s o LAMV-speci ic an ibodies
we e de ec ed in ou animals in Sou he n and Cen al
Finland, while he e was no indica ion o WNV ha ing
been in oduced in he ce id popula ions.
Finding se ological e idence o TBEV in ec ion in
ce ids indica es p e ious TBEV in ec ion. A sys emic
in ec ion is c i ical o he de elopmen o he speci ic
an ibody esponse. Non- i emic ansmission (NVT) in
oden s be ween co- eeding icks is conside ed impo an
o he main enance o he i us and i does no e-
qui e sys emic in ec ion [29, 30]. Acco ding o ou
unpublished obse a ions and he ea lie esul s by
S edmy e al. [13], moose can be hea ily in es ed by
Ixodes icks. The ole o moose as seconda y hos s
o TBEV in he aiga egion and hei po en ial o
NVT du ing ick co- eeding ha e no been in es iga ed,
bu hey a e likely o ha e a ole in ampli ying he
ick popula ions and po en ially in in oducing in ec ed
icks o new a eas.
In Cen al and Sou he n Eu ope as well as in la ge
pa s o Sweden, he oe dee is a key hos o icks,
and a good indica o o he occu ence o human
TBEV in ec ions [8, 10, 11, 31–34]. The a ailable es i-
ma es o TBEV se op e alence in oe dee and ed
dee om o he Eu opean coun ies ange om 2.4
o 40 %, wi h ma ked local a ia ion [31, 32, 35–38].
Due o he low numbe o oe dee samples in ou
s udy, he ole o oe dee in he sp ead o ci cula ion
o TBEV in Finland could no be e alua ed.
In Finland, moose is he mos abundan and mos
widesp ead wild ce id, while he la ges popula ions
and he e ec i e dispe sal o oe dee and whi e- ailed
dee a e mainly limi ed o sou h-wes Finland due o
ha sh win e condi ions and hick snow co e in o he
pa s o he coun y. Howe e , small popula ions o oe
dee exis in Lapland in sho e and i e bank a eas ha
Table 2 P e alence o an ibodies agains ick-bo ne encephali is i us in wild ce ids hun ed in 2008–2009 in Finland
n
a
n posi i e Se op e alence (%) 95 % con idence in e al (Mid-P Exac )
Moose
Male 672 7 1.04 0.46–2.05
Female 512 2 0.39 0.07–1.29
Adul 729 7 0.96 0.42–1.89
Cal 453 2 0.44 0.07–1.45
All 1213 9 0.74 0.36–1.36
Whi e- ailed dee
Male 77 1 1.30 0.07–6.24
Female 57 0 0.00 0.00–5.12
Adul 71 1 1.41 0.07–6.75
Cal 64 0 0.00 0.00–4.57
All 135 1 0.74 0.04–3.60
Roe dee
Male 11 0 0.00 0.00–23.84
Female 6 0 0.00 0.00–39.30
Adul 14 0 0.00 0.00–19.26
Cal 3 0 0.00 0.00–63.16
All 17 0 0.00 0.00–16.16
All 1371 10 0.73 0.37–1.30
a
Backg ound in o ma ion was una ailable o some o he animals in es iga ed
Ton e i e al. Pa asi es & Vec o s (2016) 9:54 Page 5 o 8

ha e less snow [39, 40]. In Sweden, he geog aphic ex-
pansion o I. icinus has ollowed he inc ease and dis-
pe sal o oe dee [11]. In Finland, he dispe sal o
whi e- ailed dee is no as e ec i e and widesp ead as
ha o oe dee [41]. In e es ingly, acco ding o unpub-
lished da a o Finnish game au ho i ies and he incidence
and geog aphical dis ibu ion o human TBE [16], he
eme gence o new human cases seemed o coincide wi h
he sp ead and inc ease o oe dee and whi e- ailed dee
popula ions a he u n o he millenium in Finland. On
he o he hand, he same a eas ha e had la ge moose
popula ions and he e a e se e al o he species ha may
also suppo he ick popula ions [42–44]. Mos o he
s udies a ailable ha e ocused on single seconda y hos
species. Sampling o all ce id species in known endemic
a eas migh elucida e hei oles in he sp ead and ci cu-
la ion o TBEV.
Collec ing samples om ce ids in co-ope a ion wi h
hun e s p o ed success ul and use ul o e alua ing he
epidemiology o zoono ic diseases ([24] and his s udy).
To analyse he ole o moose o he local epidemiology
and o he moni o ing o TBEV locally and coun y-
wide, epea ed hun e -ha es ed sampling om ce ids
could be used alongside he con inuous moni o ing o
human TBE. Good sample sizes a e achie able, and
sampling animals ha we e killed o ano he eason is
e hically sound.
The e we e mo e males han emales among he
sampled animals, and male ce ids domina e also in
he annual hun ing s a is ics in Finland [21, 45]. Eigh
o he en se oposi i e animals we e male. Male
moose and young indi iduals mig a e ac oss a wide
ange and migh he e o e ha e mo e possibili ies o
encoun e an in ec ed ick and also o ca y icks o
new loca ions [46]. In oe dee , highe TBEV-an ibody
p e alence has been seen in males e en a e he mo-
bili y is excluded [32]. In his s udy, he posi i e e-
sul s we e de ec ed mainly in a eas, which a e known
o be endemic o TBEV.
Among he animals included in his s udy, 37.9 % we e
cal es (less han 1 yea old), which is a smalle p opo -
ion han in he game s a is ics o Finland [21]. All ani-
mals included in he s udy had expe ienced a leas one
ick- eeding season, bu he exac ages o he adul ani-
mals we e no de e mined. Assuming ha he an ibodies
pe sis , i canno be es ima ed when he in ec ions we e
acqui ed. Compa ing he an ibody p e alence in old in-
di iduals wi h he p e alence in young indi iduals could
be used o de e mine whe he he incidence o in ec ions
is inc easing in he a ea. In his s udy, he p e alences
we e simila , sugges ing ecen in oduc ion, o inc eas-
ing in ec ion p essu e.
The only p e ious coun ywide se ological su ey on
he dis ibu ion and p e alence o TBEV in ec ion in
Finland was done in 1960s by sc eening TBEV an i-
bodies in ca le se um samples [18]. The se oposi i e
ca le we e om a eas whe e human cases ha e been di-
agnosed o decades. In his s udy, se e al se oposi i e
wild ce ids we e shown o inhabi he same a eas.
Du ing he wo p e ious ick- eeding seasons be o e
he collec ing o he ce id samples, human cases had
been epo ed in eigh a eas in Finland (Fig. 1). In his
s udy, se oposi i e ce ids we e de ec ed in six o he
eigh a eas. Finding no se oposi i e ce ids in wo o he
eigh a eas may be explained by sampling bias: o ex-
ample, he Helsinki ocus is an island wi h no hun ing
ac i i y. Finding no se oposi i es a ound he oci sup-
po s he p e ious obse a ions ha dis ibu ion o
TBEV is highly ocal.
One se oposi i e moose male cal (indi idual 9,
Table 1) was om Kainuu, an a ea wi h no epo s o
human TBE cases. As a cal unde 1 yea o age ollows
a cow, and cows wi h cal es usually do no do dispe sal
mig a ions, i is mos likely ha his indi idual had en-
coun e ed he i us locally. This esul could hus sug-
ges a possible new TBEV ocus, which calls o u he
moni o ing o he a ea o TBEV ci cula ion and po en-
ial human cases.
In Finland, he human TBE cases ha e eme ged mainly
nea by wa e –in he a chipelago, coas al egions, and
nea big lakes [16]. This dis ibu ion o human TBE
cases may be due o he high densi y o summe co ages
by wa e as well as long exposu e imes du ing he sum-
me holidays, which o e lap wi h he ick eeding season.
O he explana ions o he p oximi y o human TBE
cases o wa e include he ecological ac o s ha cause
he highly ocal dis ibu ion o TBEV in a ou able
mic oclima ic condi ions. Summe habi a s o ce ids
a e o en also nea by wa e [47, 48] and moose a e
known o use wa e o cool o [49]. Fu he mo e, dis-
pe sal o oe dee has ollowed he seasho es, i e s, and
lakes [40]. These habi a p e e ences migh enhance he
po en ial ole o ce ids in main aining ick popula ions
ha enable TBEV ci cula ion.
Du ing ecen yea s, human TBE cases ha e been e-
po ed in new a eas in Finland, and he s ic ly ocal pa -
e n may be changing owa ds a coalescing dis ibu ion
[14–16, 50]. The esul s o his s udy sugges ha moose
could se e as sen inels and indica o s o isk o human
TBEV in ec ions in he aiga egion whe e dee , commonly
used as sen inels o TBEV isk o humans, a e no wide-
sp ead. Su eying an i-TBEV an ibodies in wild ce ids
could be a use ul ool o moni o ing his zoonosis.
Conclusions
An i TBEV-an ibodies we e de ec ed in en ee- anging
ce ids in Finland. The in ec ions we e p esumably
au och honous, na u ally acqui ed by he ce ids om
Ton e i e al. Pa asi es & Vec o s (2016) 9:54 Page 6 o 8
hei local na u al en i onmen . Nine ou o en se o-
posi i e animals had been hun ed in a eas whe e human
TBE cases ha e occu ed, con i ming he local ci cula-
ion o he i us in he oci. Ou s udy also ound one
possible new ocus, as one se oposi i e moose male cal
was om an a ea wi h no epo s o human TBE cases.
Ou obse a ion o he geog aphical cong uence be ween
he human cases and se oposi i e moose sugges ha
moose could se e as sen inels and indica o s o TBEV
isk o humans.
Abb e ia ions
HI: hemagglu ina ion inhibi ion es ; LAMV: Lammi i us; NVT: non- i emic
ansmission; TBE: ick-bo ne encephali is; TBEV: ick-bo ne encephali is i us;
WNV: Wes Nile i us.
Compe ing in e es s
E. Ton e i has ecei ed a lec u ing ee om P ize L d o gi ing a lec u e in
he In e na ional Scien i ic Wo king G oup on Tick-Bo ne Encephali is
(ISW-TBE) mee ing, Janua y 2015. The o he au ho s decla e ha hey ha e
no compe ing in e es s.
Au ho s’con ibu ions
ET, PJ and OV designed he s udy. PJ was esponsible o planning he
o iginal sampling. ET did he labo a o y wo k. All au ho s con ibu ed o he
w i ing p ocess o he manusc ip : ET and OV con ibu ed especially o he
TBE aspec s, ET, PJ and OV o zoono ic and epidemiological aspec s, and JM
and JP o ecological and game managemen aspec s. All au ho s accep ed
he inal e sion o his manusc ip o be submi ed o publica ion.
Acknowledgemen s
The au ho s would like o exp ess hei g a i ude o I ina Suomalainen,
Uni e si y o Helsinki and Si kka Vene, The Public Heal h Agency o Sweden,
o hei help wi h he se ological assays, and o he hun e s and he s a o
Ve e ina y Pa hology and Pa asi ology, Depa men o Ve e ina y Biosciences,
Facul y o Ve e ina y Medicine, Uni e si y o Helsinki o he con ibu ions o
he o iginal sampling. We hank Vesa Ni ala (Na u al Resou ces Ins i u e
Finland) o d awing hemap. The wo k was inancially suppo ed by he
Finnish Founda ion o Ve e ina y Resea ch, S a egic De elopmen Fund o
he Es onian Uni e si y o Li e Sciences, Academy o Finland, and he Helsinki
Uni e si y Hospi al unds.
Au ho de ails
1
Depa men o Vi ology, Uni e si y o Helsinki, Facul y o Medicine, Helsinki,
Finland.
2
Depa men o Ve e ina y Biosciences, Uni e si y o Helsinki, Facul y
o Ve e ina y Medicine, Helsinki, Finland.
3
Depa men o Food Hygiene and
En i onmen al Heal h, Uni e si y o Helsinki, Facul y o Ve e ina y Medicine,
Helsinki, Finland.
4
Depa men o Basic Ve e ina y Sciences and Popula ion
Medicine, Es onian Uni e si y o Li e Sciences, Ta u, Es onia.
5
Na u al
Resou ces Ins i u e Finland (Luke), Managemen and P oduc ion o
Renewable Resou ces, Joensuu, Finland.
6
Depa men o Vi ology and
Immunology, Hospi al dis ic o Helsinki and Uusimaa (HUSLAB), Helsinki,
Finland.
Recei ed: 9 July 2015 Accep ed: 21 Janua y 2016
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