1. No category

Role of the introduced Siberian chipmunk (Tamias sibiricus) on the risk of
exposure to Lyme borreliosis in a periurban forest (Sénart, Ile-de-France)
Vourc’h G1, Marsot M1,2*, Jacquot M1**, Pisanu B2, Gasqui P1, Abrial D1, Bord S1, Masséglia S1,
Bailly X1 & Chapuis J-L1
1 : INRA, UR0346 Epidémiologie Animale, 63122 Saint Genès Champanelle
2 : : MNHN, UMR 7204 MNHN-CNRS-UP6, Centre d’Ecologie et des Sciences de la Conservation, 61 rue Buffon, 75231 Paris cedex 05
* Present address: Université Paris-Est ANSES, Laboratoire de Santé Animale, Unité Epidémiologie, code postale Maisons-Alfort, France
** Present address: MRC–University of Glasgow Centre for Virus Research, Glasgow, United Kingdom
I. Context & objective
The introduction of a new host species can increase health threats by adding a new reservoir or
by amplifying the circulation of multi-host native pathogens (‘spillback’ - Kelly et al 2009).
Our objective was to study the consequence of the introduction of the Siberian chipmunk
(Tamias sibiricus barberi) on the risk of Lyme borreliosis in a periurban forest near Paris
(Sénart, Ile-de-France) from 2005 to 2011. Chipmunks are small ground squirrels
introduced from Korea to France in the late 1960’s. II. Material & Methods
T. sibiricus
•  Sampling of chipmunks, voles, mouse and questing nymphs
•  Count of ticks on animals and on the vegetation
•  Borrelia detection in ear biopsies and nymphs
•  NGS on Borrelia housekeeping gene rplB, and the infection
related gene ospC
- Contribution from field data (Marsot et al 2013)
# infected nymphs = Burden x Prevalence x Density x Infectivity
III. Results
1- Contribution of T. sibiricus to Lyme risk
- Contribution from genetic data (Jacquot et al 2014, in prep)
Model of contribution adapated from Brisson et al 2008
65.0 60 chipmunk
10
bank vole
Autochtonous reservoirs Contribution to LB risk (%)
12
wood mouse
8
6
4
2
2007
2008
2009
Aug.-Sept.-Oct.
May-June-July
March-April
Aug.-Sept.-Oct.
May-June-July
March-April
Aug.-Sept.-Oct.
May-June-July
March-April
Aug.-Sept.-Oct.
May-June-July
0
50 40 30 20 10 0 March-April
Estimated number of infected nymphs
produced/ha/day
14
2010
Year and period
T. sibiricus α M. glareolus β Others γ 2- Mapping of the acarological risk (density of
questing infected nymphs) (Vourc’h et al in prep)
IV. Conclusion
! Chipmunks contributed over 8 times more to the risk than
sympatric bank voles (Myodes glareolus) and wood mice
(Apodemus sylvaticus)
! The presence of chipmunks was not directly related to
increase spatial risk. Further works will be done to elucidate
impacts of confounding factors (e.g. deer densities) on
spatial risk
19,000 nymphs sampled
3,100 analyzed for Borrelia, 400 positive (13%)
GLM modeling of the density of infected nymphs
High
density of
chipmunks
References
Very low
density of
chipmunks
Brisson et al 2008. Conspicuous impacts of inconspicuous hosts on the Lyme disease epidemic. Proceedings of the Royal Society B-­‐Biological Sciences 275:227-­‐235. Jacquot et al. 2014. High-­‐throughput sequence typing reveals geneJc differenJaJon and host specializaJon among populaJons of the Borrelia burgdorferi species complex that infect rodents. PLoS ONE 9:e88581. Jacquot et al, in prep. High throughput sequence typing reveals mulJple, independent transmission cycles of Borrelia burgdorferi s.l. within a local host community Kelly et al 2009. Parasite spillback: a neglected concept in invasion ecology? Ecology 90:2047-­‐2056. Marsot et al. 2013. Introduced Siberian chipmunks (Tamias sibiricus barberi) contribute more to Lyme disease risk than naJve reservoir rodents. PLoSONE 8:e55377. Vourc’h et al, in prep. Mapping human risk of infecJon with Borrelia burgdorferi, the agent of Lyme disease, in a periurban forest. Contact:
Gwenaël Vourc’h
[email protected]
INRA-Unité d’Epidémiologie Animale
Centre de Recherche de Clermont-Ferrand-Theix
http//epia.clermont.inra.fr