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Rabies
Rabies is a life threatening disease that affects the
brain and/or spinal cord, caused by a virus found in the
saliva of infected warm-blooded animals. Warm blooded
animals are those that keep their core body
temperature at a near constant level regardless of the
temperature of the surrounding environment.
HOW IS RABIES TRANSMITTED?
An image of a rabies cell.
Rabies is usually transmitted to humans, farm animals, and domesticated animals (such
as cats and dogs) after being bitten by an infected animal (known as a rabid animal). If
farm animals or domestic animals acquire rabies, they can easily pass it on to humans
by biting them since humans are often in close proximity to these types of animals.
Another method of infection is contamination of an open skin wound. This can happen if
an infected animal licks the open wound of another animal or human. Yet another method
of infection is when the mucous membranes are exposed to the saliva of a rabid animal.
A mucous membrane is one of four major types of thin sheets of tissue that line or cover
various parts of the body, such as the mouth and passages for breathing.
Typically, wild animals transmit rabies to domestic animals and humans. The types of
wild animals most likely to transmit rabies are raccoons, wild dogs, coyotes, jackals,
ferrets, skunks, bats, foxes, weasels, wolves, and other meat-eaters.
"Where Medical Information is Easy to Understand"™
Groundhogs can also become infected with rabies by living in the
quarters of a previously infected animal. Some wild animals are
relatively resistant to rabies and thus are rarely infected with it.
Such animals include rats, mice, squirrels, chipmunks, opossums,
and rabbits.
HOW DOES RABIES AFFECT THE BODY?
When one is bit by a rabid animal, the virus from the animal's saliva
first affects the nerve that is closest to the bitten area. If not
treated, the virus will travel along the nerve until it enters the brain.
WHAT ARE SIGNS AND SYMPTOMS OF RABIES?
In humans, signs and symptoms usually begin about 3 to 7 weeks after being bitten. However, signs and
symptoms may occur as early as four days after being bitten or as long as two years. The initial
symptoms are usually fever and a generalized feeling of sickness throughout the body. After 2 to 3 days,
there will be pain and tingling in the area of the body that was bitten. The skin will be sensitive to changes
in temperature. Severe muscle spasms (sudden, involuntary muscle movements) occur in the mouth and
throat. There will be excess production of saliva accompanied by drooling.
Dramatic mood changes occur, with the person being calm one moment and violent the next. Also
developing will be seizures, which are involuntary muscle movements due to overexcitement of nerve cells
in the brain. Rabies is also known as hydrophobia (fear of water) because the person becomes unable to
swallow liquids despite feeling very thirsty.
In animals, signs of rabies are quite variable in animals. The stereotypical image of a rabid animal is one
who appears angry, irritable, vicious, and violent. Indeed, this often occurs. Rabid animals are quite
dangerous as they are very quick to bite and attack. Soon after signs occur, the animals will loss sensory
and motor functioning in the back legs and will be unable to walk. Death usually occurs within 4 to 7 days
after signs begin.
Sometimes, animals can appear sleepy, moving very little, yet will aggressively go to bite or attack
anything that moves near it. Sometimes, the animals can no longer move their lower jaw. Rabid animals
showing these kinds of behaviors usually fall into a coma and die within 3 to 10 days after signs begin. A
coma is a state of deep unconsciousness in which there are no voluntary movements, no responses to
pain, and no verbal speech.
In animals, it usually takes between 3 to 8 weeks for signs to begin after exposure to rabies, depending on
the species. Other factors that influence when symptoms will begin in animals includes how much virus
entered the body, the strength of the particular strain of rabies virus, the area of the body bitten, and the
age of the bitten animal.
HOW IS RABIES DIAGNOSED?
In humans, no single test is sufficient to diagnose rabies. Samples of blood, saliva, spinal fluid and/or skin
from the back of the neck can be taken for biopsy. A biopsy is the process of removing living tissue or
cells from organs or other body parts of patients for examination under a microscope or in a culture to help
make a diagnosis, follow the course of a disease, or estimate a prognosis. A culture is an artificial way to
grow cells or tissues in the laboratory.
Saliva can be tested for the direct presence of the rabies virus. Blood and spinal fluid can be tested for
the presence of antibodies to rabies. Antibodies are types of proteins that are formed by the body to
destroy foreign proteins known as antigens. Skin biopsies are used to detect the presence of rabies
antigens in the skin nerves at the bottom of the hair follicles. Skin nerves are nerves that provide
sensation to the skin. Hair follicles are pouch-like depressions (such as the openings in the skin) through
which hair grows.
In animals, rabies can be quickly and accurately diagnosed by a biopsy of the brain after death. After the
biopsy, a test known as the direct fluorescent antibody (DFAT) tests is performed. This test uses
antibodies tagged with a fluorescent dye to detect an antigen. Fluorescent means to emit light when struck
by a form of radiant energy. In a DFAT test, the antibody will detect the presence of the rabies antigen.
HOW IS RABIES TREATED?
Before going to the doctor or nearest emergency room, doctors recommend cleaning the wounded area
immediately with soap and hot water as son as possible. Rapid treatment is very important to prevent
death. Rabies is treated by injecting a vaccine (known as human rabies immune globulin) directly into the
wound. This provides immediate protection and the dose is based on one's weight. A second vaccine is
also injected five separate times over the course of 28 days. There are three types of the second rabies
vaccine, but all provide adequate treatment for rabies. If not treated, rabies infections in humans will
cause death in about 7 to 25 days after symptoms begin.
WHO NEEDS TO BE NOTIFIED OF RABIES INFECTION?
Besides notifying one's doctor as soon as possible of rabies infection, local animal control officer also
need to be informed if someone was bitten by a wild animal. If the bite was from a domestic animal, the
animal's owner will need to be contacted to determine if the animal is up to date on its rabies shots.
CAN RABIES BE PREVENTED?
Yes. There are vaccines against rabies that one can take to prevent contracting this disease. All
domestic animals and cattle in the United States must have the vaccine. The vaccine has significantly
decreased the number of cases of dogs transmitting rabies to humans in the U.S., although this is still a
problem in many other countries that do not require vaccinations.
WHAT ELSE IS RABIES KNOWN AS?
Rabies is also known as hydrophobia.
WHAT IS THE ORIGIN OF THE TERM, RABIES?
Rabies comes from the Latin word "rabies" meaning "rage."
