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Letters
FIG 1: Adenovirus particles detected by negative contrast TEM in intestinal content from a red squirrel (Sciurus vulgaris) from Northern Ireland. Bar=100 nm
WILDLIFE DISEASE
Adenovirus particles from a wild red squirrel (Sciurus vulgaris) from Northern Ireland SURVEYS of red squirrel (Sciurus vulgaris) populations in Northern Ireland over recent decades have shown a reduction in some populations. Suspected competition for resources with the grey squirrel (Sciurus carolinensis) and the recent squirrelpox virus (SQPV) outbreak, which caused high mortality among the red squirrel population in Tollymore Forest, County Down, Northern Ireland, in early 2011 are likely contributing factors to this picture. Other viral diseases, such as adenovirus, have been described in recent years (Everest and others 2010), where sporadic and group losses have been recorded in both freeranging and captive populations. These can also be associated with significant mortality, which may have an impact on current conservation efforts. This letter describes the first detected case of adenovirus in a wild red squirrel from Northern Ireland. In October 2011, in the arboretum area of Tollymore Forest (grid reference IJ343 325), where scatter feeding was being employed to monitor red squirrel populations, an adult female red squirrel weighing 300 g was found dead. It was sent for postmortem examination at the School of Biological Sciences, Queen’s University Belfast. The examination revealed no external lesions typical of SQPV infection, and subsequent molecular analysis of the skin by PCR failed to amplify SQPV DNA. No perineal staining with diarrhoeic faeces was seen to suggest that the animal had diarrhoea or enteritis before death, but inflammation of the intestines was detected during examination, and the large intestine had fluid contents. This led to suspicion of a possible adenovirus infection, and an intestinal content sample was sent to the 188 | Veterinary Record | February 18, 2012
Animal Health and Veterinary Laboratories Agency (AHVLA) for examination. All other organ systems appeared unremarkable. Additional investigations, such as histopathology, bacteriology or parasitology, were not done. Negative contrast stain transmission electron microscopy on a sample of large intestinal content revealed numerous particles approximately 70 to 90 nm in diameter, whose size, shape and surface morphology were consistent with adenovirus (Fig 1). This indicated an adenovirus intestinal infection in a red squirrel from Northern Ireland. The animal had enteritis; however, due to limited laboratory examinations it was not possible to say definitively that the adenovirus infection was the cause of enteritis or the cause of death. Surveys in 2008 estimated the Tollymore Forest red squirrel population to be 103 animals. Recent surveys undertaken by the Tollymore Red Squirrel Group during December 2011 in the same area indicated an estimated population of just seven red squirrels, a reduction in excess of 93 per cent of the population surveyed in 2008. Disease caused by SQPV or adenovirus infection, or both, may be significant factors in explaining this decline; however, further work is required to establish this. David J. Everest, AHVLA – Weybridge, New Haw, Addlestone, Surrey KT15 3NB e-mail:
[email protected] John Griffin, Northern Ireland Forest Service, Dundonald House, Upper Newtownards Road, Ballymiscaw, Belfast BT4 3SB Neil D. Warnock, Lisa Collins, Jaimie Dick, Neil Reid, Mike Scantlebury, Nikki Marks, Ian Montgomery, School of Biological Sciences, Queen’s University Belfast, Belfast BT9 7BL
Reference
EVEREST, D. J., STIDWORTHY, M. F., MILNE, E. M., MEREDITH, A. L., CHANTREY, J., SHUTTLEWORTH, C. M., BLACKETT, T., BUTLER, H., WILKINSON, M. & SAINSBURY, A. W. (2010) Retrospective detection by negative contrast electron microscopy of faecal viral particles in wild red squirrels (Sciurus vulgaris) with suspected enteropathy in Great Britain. Veterinary Record 167, 1007-1010
doi: 10.1136/vr.e1128
