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J Am Vet Med Assoc. 1998 Nov 15;213(10):1407-12.

Prevention of the spread of rabies to wildlife by oral vaccination of raccoons in Massachusetts.

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Department of Comparative Biomedical Sciences, School of Veterinary Medicine, Tufts University, North Grafton, MA 01536, USA.



To evaluate the use of bait containing rabies vaccine to create a barrier of rabies-vaccinated raccoons in Massachusetts and to determine the effectiveness of various bait distribution strategies in halting the spread of rabies.


Prospective study.


Free-ranging raccoons.


Baits were distributed twice yearly in a 207-km2 (80-mi2) area in the vicinity of the Cape Cod Canal. Bait density and distribution strategy varied among 3 treatment areas. Raccoons were caught in live traps after bait distribution and anesthetized; blood samples were obtained to measure serum antibody titers to rabies virus. Vaccination rates were determined by the percentage of captured raccoons with antibody titers to rabies virus > or = 1:5. In addition, raccoons with clinical signs of illness inside the vaccination zone and adjacent areas were euthanatized and submitted for rabies testing.


The percentage of vaccinated raccoons differed significantly among the following 3 areas with various bait densities: high-density area with uniform bait distribution (103 baits/km2 [267 baits/mi2]) = 37%; low-density area with additional targeted bait distribution (93 baits/km2 [240 baits/mi2]) = 67%; and, high-density area with additional targeted bait distribution (135 baits/km2 [350 baits/mi2]) = 77%. Nineteen animals with rabies (15 raccoons, 3 skunks, 1 cat) were reported in the area just outside of the vaccination zone, but only 1 raccoon with rabies was reported from inside the vaccination zone.


In this suburban study area, an approximate vaccination rate of 63% was sufficient to halt the spread of rabies in free-ranging raccoons. Compared with uniform bait distribution, targeting raccoon habitats increased vaccination rates.

[Indexed for MEDLINE]

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