Mike Allan

Emergency response to raccoon rabies introduction into Ontario.

During 15 July to 4 October, 1999, rabies control programs were implemented with the objective being to contain the first three confirmed cases of raccoon rabies in Canada. The strategy, called point infection control (PIC) involved the use of three tactics: population reduction (PR), trap-vaccinate-release (TVR) and oral rabies vaccination with baits (ORV), to control the spread of raccoon rabies. A total of 1,202 raccoons (Procyon lotor) and 337 skunks (Mephitis mephitis) were captured and euthanized using 24,719 trap-nights in the three PR zones around the location of the three rabies cases, near Brockville, Ontario. That represented an 83% to 91% reduction in the raccoon populations in an approximate 225 km2 area around the three rabies cases. Raccoon density in the PR zones declined from 5.1–7.1/km2 to 0.6–1.1/km2 following control. All tested specimens were negative for rabies by the fluorescent antibody test (FAT). In addition, 1,759 raccoons and 377 skunks were intramuscularly vaccinated against rabies and released using 27,956 trap-nights in an approximate 485 km2 TVR zone implemented outside of the PR zones. A total of 856 cats from both PR and TVR areas were also captured, vaccinated and released. Cost for the three PIC operations was

Aerial distribution of ONRAB® baits as a tactic to control rabies in raccoons and striped skunks in Ontario, Canada.

363,000.00 Cdn or about

BEHAVIOR, MOVEMENTS, AND DEMOGRAPHICS OF RABID RACCOONS IN ONTARIO, CANADA: MANAGEMENT IMPLICATIONS

500.00 Cdn/km2. To further contain the outbreak, about 81,300 baits containing Raboral® V-RG oral rabies vaccine were aerially distributed on 8 and 27 September 1999, to create an 8 to 15 km wide buffer zone (1,200 km2 area) of vaccinated raccoons immediately beyond the PR and TVR zones. This was the first time that V-RG was used in Canada to orally vaccinate free ranging raccoons against rabies. Baiting costs were

The control of raccoon rabies in Ontario Canada: proactive and reactive tactics, 1994-2007.

241,000.00 Cdn or about

THE ELIMINATION OF RACCOON RABIES FROM WOLFE ISLAND, ONTARIO: ANIMAL DENSITY AND MOVEMENTS

200.00 Cdn/km2 including post baiting assessment costs. As of 31 August, 2000, thirty-five additional cases (38 in total) of raccoon rabies have occurred in the control and vaccination zones. This number is far below the level of rabies prevalence in USA jurisdictions where raccoon rabies was epizootic. In the future, PIC methodologies will continue to be used in Ontario to contain isolated cases of raccoon rabies.

Raccoon Density and Movements After Population Reduction to Control Rabies

During August 2006 and 2007, baits containing oral rabies vaccine, live adenovirus vector, known as ONRAB®, were aerially distributed in SW Ontario, Canada. Bait acceptance during 2006 was 62 and 74% in raccoons (Procyon lotor) in areas baited at 150 baits/km2 and 75 and 77% in plots baited at 300 baits/km2. During 2007, bait acceptance for raccoons ranged between 59% and 80%, and 83% and 87%, in areas baited at 75 and 400 baits/km2, respectively. Bait acceptance by skunks varied among plots (5–24%). Rabies virus-specific seroconversion during 2006 averaged 66 and 81% in raccoons in areas baited at 150 and 300 baits/km2, respectively. During 2007, seroconversion by raccoons was 76 and 84% in areas baited at 75 and 400 baits/km2, respectively. Seroconversion by skunks varied among plots (17–51%). Vaccine efficacy, as judged by the percentage of animals that consumed a bait and seroconverted, averaged 79 and 87% during 2006 for raccoons in areas baited at 150 and 300 baits/km2, respectively, and 81 and 90% in areas baited during 2007 at 75 and 400 baits/km2, respectively. Because tetracycline marking was poor in skunks, an estimate of vaccine efficacy was not possible. Aerial distribution of ONRAB® vaccine baits seems to be a feasible tactic for controlling rabies in skunks and raccoons.

PREVALENCE OF TETRACYCLINE AND RABIES VIRUS ANTIBODY IN RACCOONS, SKUNKS, AND FOXES FOLLOWING AERIAL DISTRIBUTION OF V-RG BAITS TO CONTROL RACCOON RABIES IN ONTARIO, CANADA

During 1999–2003, 127 cases of raccoon variant rabies were reported in raccoons (Procyon lotor) and striped skunks (Mephitis mephitis) in Ontario, Canada. Raccoons accounted for 98% (125/127) of the reported cases with behaviors/conditions including aggression, fighting with dogs, ataxia, vocalizations, appearance of being sick, and the presence of porcupine (Erethizon dorsatum) quills. Seventy-eight percent of the rabid raccoons were adults. Juveniles were underrepresented (22%) compared with the adult/juvenile ratios found in nonrabid Ontario raccoon populations. Of the known aged raccoons, 83% were ≤3 yr of age, and 22% of the rabid adult female raccoons had evidence of having had a litter during the year in which they were found to be rabid. The majority of rabid raccoons were reported during the fall, winter, and spring, suggesting a relationship between raccoon behavioral activities such as denning and breeding and the timing of rabies outbreaks. Multiple cases of raccoon rabies occurred at several barns, suggesting that those structures serve as focal points of rabies transmission as a result of denning activities. Movements of five rabid raccoons (range 1,564–4,143 m) were not different from movements of nonrabid raccoons in Ontario. Sixty-six percent of the rabid animals were submitted by government staff, stressing the importance of those agencies in rabies control and surveillance operations. Increased knowledge of the behaviors of rabid raccoons should assist in the development of management strategies for rabies.

Antimicrobial Resistance in Escherichia coli Isolates from Raccoons (Procyon lotor) in Southern Ontario, Canada

Proactive and reactive tactics have been utilized in Ontario, Canada, to prevent raccoon rabies from becoming established. A total of 96,621 raccoons (Procyon lotor) and 7,967 striped skunks (Mephitis mephitis) were live captured using 1,221,044 trap nights, vaccinated against rabies by injection, and released, during proactive Trap-Vaccinate-Release (TVR) programs in southern Ontario during 1994–2007. During those years, on average, 43% to 83% of the raccoon populations were vaccinated against rabies. In addition, 20,129 raccoons and 2,735 skunks were vaccinated against rabies, and 8,311 raccoons and 1,449 skunks were euthanized, using 576,359 trap nights, during reactive Point Infection Control (PIC) operations in eastern Ontario during 1999–2005. A significant correlation was detected between trapping effort and the percentage of the raccoon population that was vaccinated. Between 1999 and 2007, 132 cases of raccoon variant rabies (130 raccoons, two striped skunks) were reported in eastern Ontario. The last case occurred on 23 September 2005 with Ontario being free of reported raccoon rabies to 10 November 2008, proving that TVR and PIC are effective tactics for the control of this disease.

SALMONELLA IN RACCOONS (PROCYON LOTOR) IN SOUTHERN ONTARIO, CANADA

During 1996 to 1998, an average of 52% to 55% of the raccoon (Procyon lotor) population on Wolfe Island, Ontario was vaccinated against rabies during proactive trap-vaccinate-release (TVR) operations. However, during 1999, the percent of the population vaccinated declined to 39% and an outbreak (6 cases) of raccoon rabies occurred on the island from December 1999 to January 2000. The raccoon population on Wolfe Island declined dramatically (71% reduction) from 1,067 raccoons (mean density=8.4/km2 [6.4–12.4, 95% CI]) during 1999 to 305 raccoons (mean density=2.4/km2 [0.87–4.1, 95% CI]) in the spring of 2000. Raccoon density immediately following the outbreak was significantly lower in cells with rabies cases, suggesting that rabies had a negative effect on population size. However, raccoon density had doubled by 1 yr following the outbreak. Movement of raccoons on Wolfe Island was as great as 24 km. Male raccoons moved greater distances than females. Movements to surrounding islands were also noted for raccoons ear tagged on Wolfe Island which indicates the island could serve as a focus for greater geographic rabies spread. Point infection control (PIC) during 2000, TVR during 2001–02, and the aerial distribution of Vaccinia-Rabies Glycoprotein (V-RG) baits during 2000 and 2003–05 were used to eliminate rabies from Wolfe Island. No cases have been detected since late January 2000 (to February 2007).

Rabies in Vaccinated Raccoons from Ontario, Canada

Abstract Population reduction (PR) and trap–vaccinate–release (TVR) were used to control an outbreak of the raccoon (Procyon lotor) variant of rabies in Ontario, Canada, during 1999. Raccoon density declined significantly following PR; however, density increased significantly 9–10 months post–PR. Recolonization of PR areas with raccoons marked in TVR areas was very low with only 1.8% (32/1,759) of those raccoons dispersing into PR areas during 1999–2000. In addition, the number of raccoons dispersing from TVR areas into PR areas was not significantly greater than the number of raccoons dispersing into treatment areas where population reduction had not been implemented during 1999–2000. Raccoon movements in this study, determined by mark–recapture, averaged <4.0 km during 1999–2000 and did not differ among treatments (with or without PR). In summary, there was not a mass exodus of raccoons from TVR areas to PR areas during 1999–2000, suggesting there was not an immediate, dramatic, vacuum effect drawing raccoons into areas devoid of raccoons due to PR. However, one year post–PR, raccoon populations were near or above pre–PR densities (due to a high reproductive rate of resident raccoons), suggesting that PR would have to be an annual event if rabies is not eliminated from an area.