Avian Bornavirus as a cause of disease in free-ranging waterfowl in North America

Photo: Peg Abbott

A new strain of the recently discovered Avian Bornavirus (ABV) was identified in 2009 as a cause of neurological disease and mortality in free-ranging Canada geese and trumpeter swans  in southern Ontario.

A retrospective evaluation of pathology cases from the Toronto Zoo and the Ontario Canadian Cooperative Wildlife Health Centre (CCWHC) office from 1992 to 2011 revealed the presence of Avian Bornavirus in tissues showing lesions resembling those described in parrots affected with proventricular dilatation disease, a fatal neurological condition of parrots.

Although this virus has been isolated from apparently healthy geese, swans and ducks in the United States, our findings confirmed that it can also cause disease and death in wild waterfowl species.

Cloacal swabs and blood samples were collected from 400 free ranging Canada geese, trumpeter swans, and mute swans during the summer of 2011. The virus was found in 3.5% of the geese, 9% of the mute swans and none of the trumpeter swans (despite the fact that these species amalgamate and diseased trumpeter swans had been identified previously in this population) and showed an uneven distribution among sites. The determination of the presence of antibodies in blood, as a marker of exposure to the virus, is currently underway.

Crew sampling Canada Goose for ABV

The waterfowl strain of avian bornavirus appears broadly distributed within the ranges of North American waterfowl species and has likely been endemic here for a substantial period of time. The significance of this virus on wild populations and the possible role of waterfowl as a vector of ABV for other species are currently unknown.  Avian Bornavirus is genetically distinct from the mammalian bornaviruses and is not a cause of disease in people.

This study is part of Dr Pauline Delnatte’s graduate work; she is supervised by Dr. Dale Smith at the University of Guelph, Department of Pathobiology and the CCWHC-Ontario.

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