The emergence of squirrelpox in Ireland

Abstract

The native red squirrel Sciurus vulgaris population in Britain has been on the decline for many years. A poxvirus associated with the introduced American grey squirrel S. carolinensis has been recognized as having a major role in the reduction of red squirrel numbers by causing a deleterious disease, known as squirrelpox, from which they seldom recover. In Ireland, red squirrel numbers have also been reducing while the grey squirrel population, first introduced in 1911, has been expanding. Until now, no poxvirus-associated disease had been found in Irish red squirrels and therefore, the role of squirrelpox in the displacement of red squirrels by grey squirrels in Ireland has been questioned. Here we report, for the first time, confirmed squirrelpox disease in two populations of red squirrels in Northern Ireland. In addition, we present serological evidence of the extent of poxvirus infection in the grey squirrels from both the Republic of Ireland and Northern Ireland, including an apparent increase in the seroprevalence of antibodies against the virus in grey squirrels over the period of the study, and discuss the implications of our findings for the conservation tactics employed to protect red squirrels.

Stress in biological invasions: Introduced invasive grey squirrels increase physiological stress in native Eurasian red squirrels

“…Food competition is most intense between December and April (Wauters, Gurnell, Martinoli, & Tosi, ; Wauters, Tosi et al., ). On the British Isles, a squirrel pox virus results in disease‐mediated competition, with grey squirrels acting as a reservoir and transmitting the virus to red squirrels, for which, in most cases, the infection is lethal (McInnes et al., ; White et al., ). In Italy, the virus is not present (Romeo et al., ).…”

Squirrelpox Virus: Assessing Prevalence, Transmission and Environmental Degradation

“…More recently, there was a confirmed case in the Republic of Ireland (County Wicklow, November 2011; Sean Callanan, unpublished data ). These recent cases of SQPV in red squirrels reflect increasing seropositivity in grey squirrels and emergent cases in red squirrels throughout Ireland [16]. It is expected, therefore, that as the grey squirrel continues to expand its range, contact rates between the two species will rise, increasing the likelihood of SQPV spreading to remaining red squirrel populations [17].…”

Macroparasites of introduced parakeets in Italy: a possible role for parasite-mediated competition

“…Wapiti) to Europe (Balbo et al 1988;Novobilský et al 2007), where they may attack native red deer Cervus elaphus and have lethal consequences for Roe deer Capreolus capreolus. Similarly, squirrelpox virus mediates the amount and type of competition between alien grey squirrels Sciurus carolinensis and native European red squirrels Sciurus vulgaris in the British Isles (Rushton et al 2005;McInnes et al 2013).…”