Transcript Rabies

Rabies: The Killer Virus
Copyright 2010.
What is Rabies?
Rabies is caused by a virus.
A virus cannot reproduce on its own. It “high jacks” a cell of a
host and makes that cell produce more viruses!
The Virus
 Shaped somewhat like a bullet.
 Rabies is a special
virus because it is
lethal to pets and
 All states require
pets to be
vaccinated for
Who gets Rabies?
All mammals are susceptible to rabies. This not only includes
dogs and cats but livestock and humans as well.
Rabies is know as a zoonotic disease since it
can affect both humans and animals.
In U.S. 93% of all rabies
occurs in wild animals
Review 1
 Why do we worry so much about
 What is a zoonotic disease?
 What kinds of animals get rabies?
 How does the rabies virus reproduce?
How is Rabies
 Rabies is transmitted through the saliva of an infected
animal. This usually occurs by a bite wound.
 The virus then travels up the nerves toward the brain and
spinal cord. It even leaves one nerve cell and moves to the
next. How do you suppose it does that?
Symptoms of Rabies
 In early stages rabies is very
difficult to detect.
 After an animal is bitten it
usually takes two to twelve
weeks before it shows any
symptoms, however it may take
as long as two years.
 This period of time is known as
the incubation period.
Do I look
like I have
Symptoms of Rabies
 The first symptoms are
flu- like. Human patients
complain of feeling tired
with pain and stiffness.
 Soon afterwards, symptoms
begin to include neurological
dysfunction (problems with
the brain and nerves).
 This may include slight
paralysis, anxiety,
sleeplessness, paranoia, and
 In addition to neurological
symptoms the patient will begin to
produce large quantities of saliva and
tears. The ability to swallow and
speak are also lost.
 It is because of these characteristic
symptoms that animals often “foam
at the mouth.”
 Because patients are
unable to swallow water
they exhibit hydrophobia
or fear of water.
 This is seen in
approximately 50-80% of
 The virus spreads from
the brain to the salivary
glands where viral
particles are able to be
shed in the saliva, thus
allowing the animal to
spread the virus to
 Rabid animals may also
exhibit aggressive
behavior. This makes
them more likely to bite
other animals allowing
infection to spread.
 Once the onset of symptoms has
begun the animal usually dies
within ten days.
 Rabies is almost always fatal.
 There are only six reported cases in
all of human history of humans
surviving rabies after the onset of
Review 2
What is happening during the incubation
period of rabies?
Summarize the symptoms of rabies.
Why do bites spread rabies?
 Despite the fact that rabies is nearly
always fatal once an animal is
infected, it can be easily prevented.
 Vaccination is the most effective
and commonly utilized method of
 Vaccinations are commonly given
to pets and livestock.
 This method of prevention has
greatly reduced the incidence of
disease in many countries.
Human Prevention
The first human was successfully
vaccinated for rabies in 1885 after
being bitten by a rabid dog.
While human vaccination has been
available for many years,
vaccination is normally only given
to people who are exposed to a
rabid animal or those who are at an
increased risk of being exposed,
such as veterinarians and animal
care workers.
Public Health
 Rabies is found in
nearly all nations.
 Nations highlighted
in red were at a
high risk for rabies.
 The majority (99%)
of rabies in humans
is seen in Asia and
Is the United States at high risk for Rabies?
Remember: rabies was such a big
problem in France in the 1800s that it
caused Pasteur to make a vaccine for
rabies one of his highest priorities.
Pasteur biographies for kids
Rabies in The U.S.
 The majority of rabies cases in the U.S. are caused by
bats. Skunks and raccoons are also a major reservoir for
the disease.
 Bat bites cause the largest number fatalities since the bites
are often small and people may not even realize that they
have been bitten.
Rabies In Wild Animals
Different colors for
the same wild animal
reservoir indicate a
different variant of the
rabies virus.
Source: JAVMA. 2008. 233: 884-897
How do you interpret the graph?
States with the Most Cases
Wild Animal Sources
Raccoons Bats
New York 279
Staying Safe
 Never handle wild animals,
especially skunks, raccoons and
Never try to nurse sick animals
back to health, call your local
wildlife rescue service instead
Make sure wild animals can’t
get into your garbage cans.
Never purposely feed wild
Never handle wild animals that
are acting unafraid of humans.
Never handle wild animals that
approach you.
We’re cute,
but we could
Testing for Rabies
 Because rabies is such a deadly
disease, testing is very important.
 If a wild animal bites a person, the
animal should usually be tested
 If an person is bitten by a pet, the pet is
put in quarantine for a period of ten
days to see if it develops symptoms.
 If an animal is shedding the virus in its
saliva it will almost always start
showing symptoms within ten days.
Pets are kept away from all human contact during this time,
and watched carefully by a veterinarian.
Testing for Rabies
 Since rabies affects the brain the best way to test for it is
by examining brain tissue.
 This is done with a method call direct fluorescent antibody
 This test can only be done post mortem (after the animal is
Staying Safe
 Always vaccinate your pets!
 Puppies and kittens should be vaccinated at sixteen weeks
of age and then at one year of age.
 Every animal should get a vaccine every three years for the
rest of their life.
 In Texas, pet rabies vaccination is required by state law!
us so we
will be
Vaccinations help both you and
your best friend stay safe.
Review 3
What are some things YOU can do to
prevent getting exposed to rabies?
Rabies Research
 Most research is focused on public health (vaccines in
food for wild animals, better vaccines, vaccination
programs for pets, etc.)
 We Need:
 More fundamental research on how a virus is able to
 Research on stopping the migration of rabies
throughout the nervous system.
World Rabies Day is a worldwide
campaign against rabies. One person
in the world dies from rabies every 10
MINUTES, equaling 55,000 each year!
The disease is 100% fatal, but 100%
preventable. Human deaths are
happening most frequently in
underprivileged countries, but the
presence of rabies and it's risks are still
remarkably high even in the U.S.
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