VECTOR-BORNE AND ZOONOTIC DISEASES Volume 8, Number 6, 2008 © Mary Ann Liebert, Inc. DOI: 10.1089/vbz.2007.0167 Serological Evidence of Viruses Naturally Associated with the Montane Water Vole (Arvicola scherman) in Eastern France Nathalie Charbonnel, 1 Julie Deter, 1 Yannick Chaval, 1 Juha Laakkonen, 2,3 Heikki Henttonen, 3 Liina Voutilainen, 3 Olli Vapalahti, 2 Antti Vaheri, 2 Serge Morand, 4 and Jean-François Cosson 1 Abstract We surveyed 12 populations of the montane water vole (Arvicola scherman), previously known as the fossorial form of the water vole A. terrestris, in eastern France for antibodies (immunoglobulin G) to Puumala virus (PUUV), lymphocytic choriomeningitis virus (LCMV), and cowpox virus (CPXV). Antibodies to PUUV were found in 9 (5.5%) of 164 voles from 7 populations, antibodies to LCMV were found in 13 (26.0%) of 50 voles from 2 populations, and antibodies to CPXV were found in 66 (41.8%) of 158 voles from 7 populations. Anti- body status to CPXV was statistically associated with the phase of the A. scherman population density cycle and the percentage of grassland areas surrounding the sampling sites. Key Words: Hantavirus—Arenavirus—Orthopoxvirus—Arvicola scherman—Rodent-borne zoonoses 763 Introduction R ODENT-BORNE VIRUSES THAT CAUSE human diseases in Eu- rope include Puumala virus (PUUV), Dobrava virus (DOBV), Saaremaa (SAAV), Seoul virus (SEOV), lympho- cytic choriomeningitis virus (LCMV), and cowpox virus (CPXV). PUUV, DOBV, SAAV, and SEOV are members of the family Bunyaviridae (genus Hantavirus), LCMV is the prototypical member of the family Arenaviridae (genus Are- navirus), and CPXV is a member of the family Poxviridae (genus Orthopoxvirus). The human diseases caused by these viruses in Europe range in severity from mild to fatal. Specific rodents (usually one or two closely related species) are the principal hosts of the hantaviruses and are- naviruses for which natural host relationships have been well characterized. For example, the bank vole (Myodes glare- olus) is the principal host of PUUV in western Europe (Brum- mer-Korvenkontio et al. 1980, Verhagen et al. 1986), the Nor- way rat (Rattus norvegicus) is the principal host of SEOV (Vapalahti et al. 2003), and the house mouse (Mus musculus) is the principal host of LCMV (Childs and Peters 1993). CPXV is enzootic in rodent populations throughout Europe and western Asia (Baxby and Bennett 1999). In western Europe it is principally associated with rodents (see Crouch et al. 1995, Boulanger et al. 1996) such as bank vole (M. glareolus), common vole (Microtus arvalis), and field mice (Apodemus spp.), but frequently is transmitted to humans from cats (Baxby 1977, Willemse and Egberink 1985). The montane water vole A. scherman, previously known as the fossorial form of A. terrestris, is a grassland rodent distributed from the mountains of northern Spain through central Europe to central Romania (Wilson and Reeder 2005). A previous study revealed that A. scherman popula- tions in the Jura Mountains of France and Switzerland ex- hibit cyclic fluctuations in population density with 5- to 8- year periodicity (Saucy 1994). Such dynamics may affect the occurrence of the human diseases caused by rodent-associ- ated viruses (Davis et al. 2005). The first objective of this study was to investigate whether A. scherman in eastern France is naturally associated with hantaviruses, are- naviruses, or orthopoxviruses. The second objective was to determine whether the prevalence of orthopoxvirus infec- tions was associated with the phase of the population den- sity cycle. 1 Centre de Biologie et de Gestion des Populations (CBGP), INRA EFPA, Campus International de Baillarguet, Montferrier s/Lez Cedex, France. 2 Department of Virology, Haartman Institute, University of Helsinki, Helsinki, Finland. 3 Finnish Forest Research Institute, Vantaa, Finland. 4 Institut des Sciences de l’Évolution de Montpellier (CNRS–UMR 5554), Montpellier, France.