Non‐invasive genetic studies and virus epidemiology

Opportunistic viral surveillance confirms the ongoing disease threat grey squirrels pose to sympatric red squirrel populations in the UK

“…AdV has been detected in areas of Italy where grey squirrels are present, 21 where parallel research to other studies 48,49 detected infections by PCR analysis from animals killed by trauma, such as road collisions, and which presented as asymptomatic cases with no pathology present on gross examination. It should be recognised that the majority of AdV particle TEM detection cases are only recorded as AdV‐associated deaths, with no confirmation of pathogenic infection presence.…”

“…SQPV is carried asymptomatically by grey squirrels and spreads into red squirrel populations, where it causes pathogenic infection and often high mortality. 14 However, it is important to highlight that, unlike SQPV, AdV is found within allopatric red squirrel populations within the UK environment, 48,49 from the offshore islands of the Isle of Wight and Jersey but also from further afield in mainland Europe (Germany), where the grey squirrel is absent. 24,25 A recent Portuguese AdV detection 50 described a case in a red squirrel translocated during a reinforcement programme.…”

“…Two studies 24,25 describe data matching the AdV strain detected in the red squirrel in Germany, being the same as that described from the UK and for the grey squirrel, while other studies provide further evidence of a single red and grey squirrel AdV strain. 27,28,31,44,49 In contrast, when investigating murine AdV sequence identity, strain divergence of close to 40% is observed, leading us to perhaps presume that a murine or other nonsciurid species AdV presence in sciurids would not be realistic.…”