Tuesday, September 30, 2008

The Epidemiology of Rabies in the U.S.

In any given year about 7,500 cases of rabies in nonhuman animals are reported to the Centers for Disease Control and Prevention. Wild animals account for approximately 93% of all cases of rabies reported -- most of the rest are in domestic/feral cats, dogs and farm animals.

The average human in the U.S. is FAR more likely to be struck dead by lightning than to come down with rabies, much less die from it. That said, most Americans are not encountering (much less handling) raccoons, fox, skunks, groundhogs, possum and feral cats on a regular basis.

Raccoons continued to be the most frequently reported rabid wildlife species (37.2% of all animal cases during 2001), followed by skunks (30.7%), bats (17.2%), foxes (5.9%), and other wild animals, including rodents and rabbits (2.3%).

Raccoons have been recognized as a reservoir for rabies in the southeastern states since the 1950s. An outbreak that began during the late 1970s in the mid-Atlantic states has been attributed to the translocation by hunters of infected raccoons from Florida.

Raccoon rabies is now found in all of the eastern coastal states as well as Alabama, Pennsylvania, Vermont, West Virginia, and Ohio.

Foxes (mainly Vulpes vulpes) accounted for 5.9% of all cases of rabies in animals reported in 2001. The majority of cases of rabies in foxes (360 out of 437 cases) were reported by states affected by the raccoon-associated variant of the rabies virus. In 2001 Alaska reported 45 cases of rabies in fox, Maryland reported 38 cases, and North Carolina reported 56 cases.

During the past 2 decades, more than 100 million doses of vaccine-laden bait have been distributed over 6 million square kilometers in Europe, with promising results for controlling the disease in red foxes. The use of oral vaccination in Switzerland during the past 20 years resulted in a declaration of rabies-free status in 1998, and a similar declaration was made by France as of the end of 2000.

Air-dropped rabies-vaccine baits are now being dropped in many parts of the Eastern and mid-Western United States, and good-to-excellent results are being observed.

To see a larger view of the CDC incidence map of rabies in fox (2001) >> click here

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