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Rabies is a viral disease that affects all warm-blooded animals, including humans. The virus is transmitted through saliva when an affected animal bites a susceptible victim. On rare occasions, the rabies virus can enter the body through deep scratch wounds (or any break in the skin or mucous membranes) or by inhalation. Inhalation of the virus is an unusual method of transmission; however, it can occur in caves that are heavily populated by rabid bats.
A rabid animal bites its victim and injects saliva containing the rabies virus. In the newly infected animal, the virus begins to multiply. Virus multiplication occurs in the area surrounding the bite wound. After a period of time, virus particles enter large nerves and travel toward the spinal cord and brain. Once inside the brain, the rabies virus multiplies a second time. As multiplication occurs, viruses pass to the salivary glands. This is particularly important and accounts for the danger associated with saliva.
Early symptoms include personality changes. Friendly animals become shy, and reserved animals often become aggressive.
Two forms of rabies are recognized: the "furious" or "mad" type and the "paralytic" or "dumb" form.
The most common form of rabies is the furious type. Animals hallucinate and snap at imaginary objects. A rabid animal is extremely aggressive and may attack or bite other animals as well as his (or her) owner. Other signs include excitation, irritability, photophobia (extreme sensitivity to light) and seizures.
In the United States, wild animals are the reservoir for the rabies virus. The most common wildlife species to spread rabies to domestic animals and humans in the Northern Hemisphere are the skunk, bat, raccoon, fox, and coyote. Raccoons and skunks are particularly a problem due to their presence in urban and suburban areas. Pets become infected when they come into contact with these animals (and are bitten).
Virus in the infected animal's saliva enters the victim's tissues during the bite. The virus attaches to the local muscle cells for a couple of days before penetrating to local nerves and beginning its slow ascent to the brain. Once in nervous tissue, the virus is not accessible to the immune system and may safely proceed, although the journey is slow taking up to one year (average time between bite and detectable virus in the brain is 20 to 30 days). Virus ultimately reaches the brain and in two to three days more is evident in all body secretions including saliva. At this point, the disease becomes transmissible and symptoms begin.
IT CAN TAKE UP TO A YEAR FROM THE TIME OF THE INITIAL BITE BEFORE SYMPTOMS BEGIN TO SHOW. ONCE SYMPTOMS SHOW, TREATMENT IS NEARLY IMPOSSIBLE.
PRODROMAL STAGE (the first 1.5 days after symptoms have started)
EXCITATIVE STAGE (Next 2-3 days)
PARALYTIC OR DUMB STAGE (Next 2 days)
Once the virus has been released to body secretions, it is again accessible to the immune system; however, the patient dies before an adequate immune response is mounted.
The classical symptoms of rabies described above may not be obviously recognizable, making diagnosis difficult if not impossible in a living animal. Long quarantines are often needed to determine if infection has occurred.
When human exposure to the animal in question is involved, what happens depends on an assortment of criteria. If the animal in question is dead, its brain can be tested for rabies. There is no test for rabies in a living animal but since we know that death follows quickly after the virus becomes contagious, a living animal can be confined for 10 days. If the animal is still alive 10 days after biting a person, then the bite could not have transmitted rabies.
Vaccinating pets protects them from rabies!
Vaccinations begin at three to four months of age and should be continued throughout the animal's life.