Aleutian mink disease virus in free-ranging mustelids in Finland - a cross-sectional epidemiological and phylogenetic study.

Aleutian mink disease virus (AMDV) can cause severe immune-complex-mediated disease in American mink. AMDV has also been detected in several other mustelid species with potential negative impact on their health and population. A molecular and cross-sectional epidemiological study was conducted to obtain data on the prevalence, distribution, transmission and diversity of AMDV strains in Finnish free-ranging mustelids and risk factors associated with infection. The presence of anti-AMDV antibodies and/or AMDV DNA was tested from 308 samples representing eight mustelid species and 17 administrative regions. Positive samples were detected across Finland, and in 54 % (31/57) of feral American mink, 27 % (7/26) of European badgers and 7 % (1/14) of European polecats. Samples from Eurasian otters, European pine martens, least weasels, stoat and wolverine were negative. Major risk factors for infection were the species American mink with 335 and badger with 74 times higher odds than other species, and the years 2006-2009 with five times higher odds than the years 2010-2014. No clustering according to species, geographical origin or year was evident in phylogeny, except for four divergent sequences from Estonian badgers that formed a separate phylogroup distinct from other AMDV strains. This study showed that AMDV was prevalent in certain species of Finnish free-ranging mustelids and widely distributed across Finland. Furthermore, the free-ranging mustelids carried both strains similar to those found in farmed mink, but also distinct strains that may represent novel amdoparvoviruses.