A retrospective economic analysis of the Ontario red fox oral rabies vaccination programme.

Ontario initiated a red fox (Vulpes vulpes) oral rabies vaccination (ORV) programme in 1989. This study utilized a benefit-cost analysis to determine if this ORV programme was economically worthwhile. Between 1979 and 1989, prior to ORV baiting, the average annual human post-exposure treatments, positive red fox rabies diagnostic tests and indemnity payments for livestock lost to rabies were 2248, 1861 and $246,809, respectively. After baiting, from 1990 to 2000, a 35%, 66% and 41% decrease in post-exposure treatments, animal rabies tests and indemnity payments was observed, respectively. These reductions were viewed as benefits of the ORV programme, whereas total costs were those associated with ORV baiting. Multiple techniques were used to estimate four different benefit streams and the total estimated benefits ranged from $35,486,316 to $98,413,217. The annual mean ORV programme cost was $6,447,720, with total programme costs of $77,372,637. The average benefit-cost ratios over the analysis period were .49, 1.06, 1.27 and 1.36, indicating overall programme efficiency in three of the four conservative scenarios.

Elimination of rabies from red foxes in eastern Ontario.

The province of Ontario (Canada) reported more laboratory confirmed rabid animals 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 (approximately 100,000 km2), the region with the highest human population density and greatest agricultural activity. Rabies posed an expensive threat to human health and significant costs to the agricultural economy. The rabies variant originated in arctic foxes: the main vector in southern Ontario was the red fox (Vulpes vulpes), with lesser involvement of the striped skunk (Mephitis mephitis). The Ontario Ministry of Natural Resources began a 5 yr experiment in 1989 to eliminate terrestrial rabies from a approximately 30,000 km2 study area in the eastern end of southern Ontario. Baits containing oral rabies vaccine were dropped annually in the study area at a density of 20 baits/km2 from 1989-95. That continued 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 1980's, an average of 235 rabid foxes per year were reported in the study area. None have been reported since 1993. Cases of fox rabies in other species also disappeared. In 1995, the last bovine and companion animal cases were 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 York (USA). The success of this experiment led to an expansion of the program to all of southern Ontario in 1994. Persistence of terrestrial rabies, and ease of elimination, appeared to vary geographically, and probably over time. Ecological factors which enhance or reduce the long term survival of rabies in wild foxes are poorly understood.

Background prevalence of tetracycline-like fluorescence in teeth of free ranging red foxes (Vulpes vulpes), striped skunks (Mephitis mephitis) and raccoons (Procyon lotor) in Ontario, Canada.

We collected and examined teeth from 3406 red foxes (Vulpes vulpes) collected in Ontario, Canada, from 1978 to 1986, prior to large scale rabies vaccine baiting. We found tetracycline-like fluorescence in five (0.2%) of the samples. Also, we observed similar fluorescences in five (0.4%) of 1103 striped skunks (Mephitis mephitis) and in six (0.8%) of 744 raccoons (Procyon lotor). The low prevalence of such marks would not appear to invalidate the use of tetracycline as a marking agent in vaccine baiting trials.

Tactics for the control of wildlife rabies in Ontario (Canada).

Two different tactics are currently being utilized to control rabies in foxes, skunks and raccoons in Ontario, Canada. The first tactic, which involves live-capturing with cage-traps and vaccinating by intramuscular injection, was successful in immunizing 54%-72% of the skunk and raccoon populations in a 60 km2 area of Toronto, Ontario. This area has been free of rabies for two-and-a-half years. The second tactic, involving the distribution of baits containing modified live-virus (ERA) rabies vaccine, was implemented to control rabies in foxes in both urban and rural areas of Ontario. In Toronto, 50% and 63% of the foxes were vaccinated during 1989 and 1990, respectively. Over the same period, 45% and 61% of the foxes in a 30,000 km2 area of south-eastern Ontario were immunized. Rabies is declining in both of these areas. A contingency plan has been devised to control an epizootic of raccoon rabies which is threatening to invade Ontario from the United States of America.

Light sensitivity and substrate penetration by eleutheroembryos of brook (Salvelinus fontinalis) and lake charr (Salvelinus namaycush) and their F1 hybrid, splake.

Critical light levels necessary to produce avoidance movements in photonegative free embryos (eleutheroembryos) of the lake and brook charr and their F1 hybrid splake, (S. namaycush X S. fontinalis) were determined and compared to previously studied movement patterns within artificial substrate systems. Light sensitivity was inversely related to depth of penetration into artificial substrates. As well, brook charr held in vertical profile tanks under either 14 : 10 h light : dark cycles or total darkness showed similar movement patterns. These results do not support previous hypotheses concerning the role of ambient light in the initial downward movement of eleutheroembryonic salmonids within spawning redds.