Rabies is caused by an RNA virus that can affect any warm-blooded animal.  There have been 32 deaths from rabies in the United States between 1980-96.  There are approximately 200 rabid dogs out of 50,000,000 in the U.S.  Approximately 20,000 individuals receive rabies prophylaxis in the U.S. each year and expenditures for rabies approximate 1 billion dollars per year. 

There is susceptibility difference among different species of animals. In the U. S., raccoons are the predominating infected species and source of spread.  In the Midwest, in addition to raccoons, skunks, bats, and foxes are also frequent carriers of rabies.  Because of immunization practices, dogs and cats are rarely infected.  In underdeveloped countries, wild dogs are responsible for most of the cases of rabies. 

After the bite of a rabid animal, the virus binds to cells at the site and multiplies.  The virus enters the central nervous system via peripheral nerves and travel to the spinal cord ganglions.  At this time the first symptoms develop, pain and paresthesias at the site of the bite. The virus is slowly transported to the brain and this may take days to years.  Once in the brain, the virus affects the limbus system and produces bizarre and aggressive behaviors.  The viruses then travel to other parts of the body by peripheral nerves including the salivary glands.  Spread to the salivary glands makes the animal infectious.  Most animals succumb about ten days after the onset of clinical symptoms. 

In humans, exposure is from the bite of a rabid animal, contamination of an open wound with saliva of an infected animal, or contact with viruses in a laboratory setting.  Although exposures without a true bite can inoculate a large  number of viral particles, cases of rabies associated with scratches, abrasions, or licking are unusual.  There have been case reports of rabies after exposure to aerosolized saliva in caves and after the transplantation of corneas from donors with unrecognized rabies.  Exposure to urine, feces, blood, or petting a rabid animal, does not constitute an exposure.

Prevention
1. Teach children not to provoke animals.
2. Leash laws
3. Don't domesticate wild animals

Treatment
1. Thorough cleansing of wound area with soap and water and high-pressure irrigation.
2. Institution of post exposure prophylaxis is dependent on the geographic area, the species, type of exposure, and the likelihood that the animal was rabid.   When in doubt, treat.
3. Treatment instituted within 5 days will give protection. 
4. Capture any wild animal if possible and autopsy their brain. If the animal is not available, treatment recommendations are based on rabies epidemiology in the region. 
5. Reactions to the vaccine are rare.
6. Post exposure prophylaxis
     a. Rabies Immune Globulin- 20 IU/kg.
          i. Should inject as much as possible into the wound site and the remainder should be given IM in the gluteal region with a different needle and syringe.
     b. 4 doses of Human rabies vaccine given on days 0, 3, 7, and 14
7. Pre-exposure prophylaxis 
     a.  Recommended for veterinarians, animal handlers, individuals who work in labs that work with rabies viruses, and individuals traveling to countries with a large population of wild dogs. 
8 .CDC rabies hotline 404 639-1050 or 1075.