Squirrelpox virus reservoir expansion on the east coast of Ireland

The European red squirrel (Sciurus vulgaris) has suffered a 20 % decline in range in Ireland since the introduction of the eastern grey squirrel (Sciurus carolinensis) in 1911. In the UK, squirrelpox virus (SQPV) has been identified as being a major contributor to the decline of red squirrel populations but has only recently been confirmed in a red squirrel from Wicklow in Ireland with anecdotal references to a previous outbreak in the Shankill area of south County Dublin and a case in Kilmacanogue, north County Wicklow. The current study examined a sample of grey squirrels from these areas for SQPV seroprevalence. Enzyme-linked immunosorbent assay (ELISA) tests were carried out on sera from 51 grey squirrels culled from two sites in south County Dublin, areas A and B, and a third site in north County Wicklow, area C. The results indicated declining SQPV seroprevalence rates moving northwards from Wicklow, 55 % in area C, 50 % in area B and 11 % in area A. The low levels of seropositivity in Killiney (A) suggest that this is the wave-front of grey squirrel expansion from Wicklow and that the population may not yet have reached the threshold density for SQPV transmission to the red squirrel population to occur. The results of this study indicate that there is potential overlap between seropositive grey squirrel populations and susceptible red squirrel populations with obvious implications for conservation and management