Elimination of rabies from red foxes in eastern Ontario

The province of Ontario (Canada) reported more laboratory confirmed rabid a nimals than any other state or province in Canada or the USA from 1958-91, with the exception of 1960-62. More than 95% of those cases occurred in the southern 10% of Ontario (approximate to 100,000 km(2)), the region with th e highest human population density and greatest agricultural activity. Rabi es posed an expensive threat to human health and significant costs to the a gricultural economy. The rabies variant originated in arctic foxes: the mai n vector in southern Ontario was the red fox (Vulpes vulpes), with lesser i nvolvement of the striped skunk (Mephitis mephitis). The Ontario Ministry o f Natural Resources began a 5 yr experiment in 1989 to eliminate terrestria l rabies from a approximate to 30,000 km(2) study area in the eastern end o f southern Ontario. Baits containing oral rabies vaccine were dropped annua lly in the study area at a density of 20 baits/km(2) from 1989-95. That con tinued 2 yr beyond the original 5 yr plan. The experiment was successful in eliminating the arctic fox variant of rabies from the whole area. In the 1 980's, an average of 235 rabid foxes per year were reported in the study ar ea. None have been reported since 1993. Cases of fox rabies in other specie s also disappeared. In 1995, the last bovine and companion animal cases wer e reported and in 1996 the last rabid skunk occurred. Only bat variants of rabies were present until 1999, when the raccoon variant entered from New Y ork (USA). The success of this experiment led to an expansion of the progra m to all of southern Ontario in 1994. Persistence of terrestrial rabies, an d ease of elimination, appeared to vary geographically, and probably over t ime. Ecological factors which enhance or reduce the long term survival of r abies in wild foxes are poorly understood.