RABIES

Rabies is a viral disease of wild and domestic animals. It is particularly prevalent in feral dogs, while humans are occasional victims. The virus is transmitted in saliva and enters the body through puncture wounds caused by bites, or via abrasions, open cuts, or sores. The virus attacks the central nervous system by migrating up peripheral nerves from the site of entry. It can take several months to reach the central nervous system, so there can be a very long incubation period. In humans and most animals it is almost invariably fatal, but bats may be symptomless carriers. Rabies occurs almost worldwide, but it has been eliminated from Britain, Iceland, and Scandinavia through rigorously enforced animal quarantine, which has also prevented it from ever gaining entry to Australia. Because of the long incubation period, exposed animals must be quarantined for many months. In much of the world, including the United States and Canada, rabies is endemic in foxes, raccoons, skunks, bats, and other wild animals, and these occasionally infect domestic animals and humans.

The French bacteriologist Louis Pasteur developed a postexposure vaccine against rabies in 1885, using desiccated nerve tissue containing the virus. For many years, Pasteur's prolonged and painful course of injections was used to treat all persons who had been bitten by suspected rabid animals. Prophylactic immunizations for animal and human use have been much improved by the human diploid cell vaccine (HDCV), developed in the 1970s. Rabies immune globulin is used for postexposure prophylaxis. When humans are bitten by a suspected rabid animal, the animal should be killed and its brain examined for evidence of infection. Vaccination of wild animals utilizes an oral vaccine delivered in baits.

JOHN M. LAST

(SEE ALSO: Communicable Disease Control; Immunizations; Pasteur, Louis; Veterinary Public Health)

BIBLIOGRAPHY

National Center for Infectious Diseases. Rabies. Available at http://www.cdc.gov/ncidod/dvrd/rabies.