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

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/km(2) and 75 and 77% in plots baited at 300 baits/km(2). During 2007, bait acceptance for raccoons ranged between 59% and 80%, and 83% and 87%, in areas baited at 75 and 400 baits/km(2), 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/km(2), respectively. During 2007, seroconversion by raccoons was 76 and 84% in areas baited at 75 and 400 baits/km(2), 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/km(2), respectively, and 81 and 90% in areas baited during 2007 at 75 and 400 baits/km(2), 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.