Things to know about Rabies Viral Infectious Disease

Rabies is a viral infection of the brain and nerves. It is one of the most dreaded diseases, and its reputation is well-earned. Death from rabies is both extremely unpleasant as well as virtually certain.

Fortunately, rabies in humans has nearly been eradicated, with only one to three cases occurring per year since 1960. Currently, about 70 percent of reported rabies occur in wildlife. Wild animals are the major source of infection for both humans and domestic animals; however, most antirabies treatments are given because of bites by dogs and cats.

Meat-eating animals, such as dogs, cats, foxes, raccoons, skunks, coyotes, and wolves are more likely to be infected with rabies. Fox rabies is predominant in Virginia and Kentucky and skunk rabies in Oklahoma, Arkansas, Texas, Missouri, and Tennessee.5 Raccoon rabies is found in Florida and Georgia and is moving northward into the Carolinas.6 Bats are notorious carriers and are the only animals that can carry the virus without suffering the disease. In the United States, human rabies has never resulted from the bites of rabbits, squirrels, mice, cats, hamsters, guinea pigs, gerbils, chipmunks, and other rodents; and antirabies treatments are almost never necessary for bites of these animals.7 The occur­rence of rabies varies significantly in different areas and the local Health Department should be consulted if any uncertainty arises.

The agent of rabies is a virus which attacks the nervous system. From the site of the bite, it spreads along the nerves until it reaches the brain. The virus is spread in the saliva of infected animals, and it can enter the nervous system through any break in the skin, or through a mucous membrane such as the eyes or mouth. Most rabies exposures are from bites. The incubation period is usually three to six weeks, but can be as brief as six days or as long as twenty-three months, depending on the number of nerves that the virus can enter in the vicinity of the bite. If the nerve supply for the area is rich, the disease will appear more rapidly. Thus bites of the face or fingers have the shortest incubation period, especially if they are severe or multiple. Rabies lasts only about two to six days and is almost invariably fatal.

The victim often has periods of delirium, mania, and convulsions, but may also be stuporous and indifferent. As a result, animal rabies is often classified as "furious" or "dumb." In funous rabies, the animal is very irritable at first and then becomes increasingly fearful and nervous. It may not recognize familiar humans and show only an insane desire to bite. Dumb rabies has a very brief excitation period. The animal then becomes indifferent and apathetic and goes off by itself. Soon it becomes stuporous and paralysis develops, followed by coma and death. Obviously, furious rabies is much more dangerous to humans.

The term hydrophobia is often used for rabies. This means "fear of water" and is caused by spasm of the muscles of swallowing, resulting in excessive drooling and "foaming at the mouth."