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Rabies in the Americas
The International Conference on Rabies in the Americas (RITA)
has been held annually since 1990 with the objective of presenting
and discussing the advances in topics related to rabies. In recent
years, participants have included almost 250 persons representing
various countries in the Americas, principally North America, as
well as other continents
A BRIEF HISTORY OF RABIES
Rabies is an infectious and contagious disease of the central
nervous system. It has been known since the ancient days of 2300
B.C. This lethal virus still exists in almost all parts of the
world.
Once infected, and left untreated, this disease is usually
fatal. The rabies virus is concentrated in the saliva, mucus
membranes and central nervous tissue of a rabid animal. Only
humans, and other mammals, can become infected through a cut or
scratch from an animal with rabies, or if the rabies virus comes
in contact with the moist tissues of the mouth, nose or eyes.
There are two ways that rabies symptoms appear, dumb and
furious. Both can cause abnormal behavior. Immediately prior to
death, animals with furious rabies will appear to be ‘mad’:
frothing at the mouth and biting anything that gets in their way.
They may show extreme excitement and attack stationary things or
animals. Bouts of furious rabies usually alternate with periods of
depression.
In dumb rabies, there is no ‘mad’ period. With dumb rabies,
paralysis, usually of the lower jaw, and a drooping head are the
first sign of the disease. The paralysis quickly spreads to limbs
and vital organs and death quickly follows. Animals with dumb
rabies may become depressed and retreat to isolated places. Some
may appear ‘tame’, having no fear of humans.
RABIES SYMPTOMS AND TREATMENTS
Rabies can manifest itself as ‘dumb’ or ‘furious’
rabies.
Dumb Rabies:
 | some animals may become depressed and retreat to isolated
places.
| wild animals, especially skunks, may lose their fear of
humans.
| animals may show signs of paralysis such as abnormal facial
expressions, drooping head, sagging jaw, or paralyzed hind
limbs. |
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Furious Rabies:
| animals may show extreme excitement and aggression.
| animals may gnaw and bite their own limbs.
| animals may attack stationary things or other animals.
| bouts of furious rabies usually alternate with periods of
depression. |
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How long does it take for an animal to show the symptoms of
rabies after it has been infected?
The time between exposure to the virus and the onset of
symptoms can range from about two weeks to over a year in some
cases.
Can animals have rabies without showing any symptoms?
Yes. The rabies virus can be found in animal saliva days before
any obvious symptoms develop. Once symptoms develop, the animal
almost always succumbs to the disease.
Treatment for Humans against Rabies
All people who are knowingly exposed to rabies must be treated
immediately. This treatment usually consists of a series of five
injections given over a one-month period. The treatment is safe
and effective
Arctic Fox Strain
This strain of rabies invaded southern Ontario, between 1954
and 1959, from northern Ontario and Quebec. In northern Ontario,
the disease disappeared in 1972 but reappeared in 1989. It was
eliminated from southeastern Ontario, but still persists in certain
areas across southwestern Ontario.
Raccoon Strain
This strain of rabies (mid-Atlantic) was first reported in
Florida in 1947, remained in the southeastern coastal parts of the
USA until 1977, and then began to rapidly spread northward. It
entered Ontario in July 1999. It was first discovered in a
juvenile raccoon found dead in a dog kennel, just northwest of
Prescott. To date (December 2005) 132 cases have been reported within
this general area of Ontario. Wolfe Island near Kingston was
held at six cases during December 1999 and has been rabies
free for more than four years.
Bat Strain
These strains of rabies were first diagnosed in Ontario in
1961. There are eight species of bats in Ontario, all of which
have their own strain of the disease, but the most common are
Little Brown bat, Big Brown bat, and Silver-haired bat. Although
bats are the most widely distributed mammal, less than 2% of bats
submitted for testing have rabies (2% of all bats acting
strangely, dead, or have possibly bitten a human or pet). In the
overall population, this percentage would be much lower.
What is rabies?
Rabies is an infectious disease caused by a virus that infects
nerves in mammals. The rabies virus travels to the brain through
nerves. Once it reaches the brain, the virus reproduces and then
travels through the nerves back to most parts of the body.
Eventually, the virus reaches the salivary glands where it is
released into the saliva in the mouth. By this time, the disease
has usually damaged the brain, producing either submissive or
violent behaviour. It almost always causes death. Death is by
asphyxiation or cardiac arrest.
How is rabies spread?
Rabies is spread by infected animals to other mammals
(including humans) through saliva. This can occur in three main
ways:
| biting
| contact with the virus through an open cut, sore or wound
| contact with the virus through mucous membranes (mouth,
nasal cavity, eyes) |
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What are the symptoms of rabies?
In humans: early symptoms of rabies may include numbness around
the site of the bite, fever, headache, and a general sick feeling.
Later symptoms may include muscle spasms and hydrophobia (fear of
water). In an adult, clinical symptoms can appear as soon as two
weeks after exposure, or up to one year following exposure. Once
symptoms appear, death is usually imminent.
In animals: depression, partial paralysis, sometimes aggressive
behaviour, followed by death.
Are there different types of rabies?
There are different strains, but unlike flu strains, rabies
vaccine for humans and rabies vaccine for domestic animals
protects against all strains of rabies in North America. There are
three strains presently in Ontario: ‘arctic fox’ (mainly found
in foxes and skunks), ‘mid-Atlantic’ raccoon (mainly found in
raccoons), and a variety of bat strains. In other parts of Canada
and North America, there are a number of skunk, fox, and other bat
strains.
Are some strains of rabies more dangerous than others?
All strains are dangerous. At present, there is no proof that
any one strain is more dangerous to humans than another. The most
common strain to kill humans in North America is the bat strain.
Any mammal (including
humans) can contract rabies
How long does the rabies virus last outside the body and in
dead animals?
The life span of the rabies virus depends on the duration of
its exposure to air and climatic conditions. Freezing does not
kill the virus.
Always assume that a dead animal may still have the virus
Does rabies kill people?
Yes. According to the Guinness Book of World Records, rabies is
one of the few diseases which is 100% fatal. There have only been
6 documented cases world-wide of an individual surviving rabies.
In one case, the patient did not die of rabies but never made a
full recovery. Worldwide, an average of 50,000 people die of
rabies each year, mostly in India. All North American strains of
rabies are fatal once clinical symptoms develop. Fortunately, a
series of vaccinations can prevent death if administered
immediately after exposure. One vaccine protects humans against
all strains of rabies found in North America.
How would I become exposed to rabies?
Rabies is spread by infected animals through:
| bites
| contact with an open cut, sore or wound
| contact with mucous membranes (mouth, nasal cavity, eyes)
| careless handling of a dead rabid animal |
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Usually, people come into contact with rabies through their
pets. Rabies in a single dog or cat could expose many human
beings. Only 10% of reported rabid animals are cats or dogs, but
they are responsible for about 60% of all human post-exposure
vaccinations.
What should I do if a suspected rabid animal bites me?
Wash the bite or scratch well with soap and warm water,
immediately.
Call your family physician, or go to the nearest hospital for
treatment.
Rabies is deadly, so all bites and scratches from a suspect
animal must be reported.
Either you, your doctor or the hospital emergency department
must report the incident to the local health unit.
If you are bitten or scratched by an animal with rabies, you
will receive a series of 5 shots of post-exposure rabies vaccine.
More shots may be required depending on the severity and location
of the exposure.
How do I know if I have rabies?
Early symptoms of rabies may include numbness around the site
of the bite, fever, headache, and a general sick feeling. Later
symptoms may include muscle spasms, aerophobia (fear of air gusts),
hydrophobia (fear of water), and difficulty breathing.
In an adult, clinical symptoms can appear as soon as two weeks
after exposure, or up to one year following exposure. It depends
on where the bite is located, the severity of the wound, and
the strain of rabies, among other factors. Once clinical symptoms
develop, however, it may be too late.
If you have sufficient reason to believe that you have come
into contact with the rabies virus, contact your physician or go
to a hospital or clinic.
You may have come into contact with the rabies virus if:
| a potentially rabid animal has bitten you.
| saliva, or other tissue, from a potentially rabid animal
(dead or alive) came into contact with an open cut, sore,
wound or mucous membrane (mouth, nasal cavity, eyes).
| you woke up and discovered a bat, live or dead, in the
vicinity of where you were sleeping
What should I do if I think I have rabies?
Contact your family physician, emergency department of the
closest hospital, or a walk-in-clinic.
How long does it take to get rabies after being infected?
The speed at which symptoms appear depends on where the
bite is located, the size and depth of the wound, and the
strain of rabies, among other factors.
In people, the incubation period is usually two to eight
weeks.
If you suspect you have come into contact with a rabid
animal, contact a physician immediately.
Is rabies treatment painful?
No. The modern treatment consists of five injections in the
upper arm over a 28-day period. It is much less painful than
treatments of the past, when 14 injections were given in the
abdomen, once a day, over a period of 2 weeks.
How can I reduce my risk of rabies exposure?
| Make sure your dogs and cats are vaccinated against
rabies every three years (annually in some cases—check
with your veterinarian).
| Don't allow your pets to wander freely, particularly at
night.
| Keep your distance from unfamiliar animals, particularly
ones that appear sick, even if they are babies.
| Don't feed wild animals.
| Attempt to keep bats from getting inside your home. |
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If I come in contact with urine or feces should I be
worried about rabies?
Contact with urine, feces or blood of a rabid animal is not
normally considered infectious. However, you should consult
your family physician or local health unit if you are exposed
to these substances as you may have been exposed to other
diseases and parasites.
May I be vaccinated against rabies?
Yes. Rabies shots are given by a family physician or
traveler's health clinic. Contact your physician to determine
the cost. There are three shots spanning 21 days. Immunity
levels (the level of resistance to rabies) should be checked
each year. Boosters (subsequent shots that will increase your
immunity) are given when necessary and duration of immunity
varies from person to person.
Shots are recommended for international travelers entering
high risk areas (as defined by the World Health Organization)
and for people involved in activities with high potential for
contact with the virus: e.g. trappers, wildlife rehabilitators, slaughterhouse workers, veterinarians, etc.
What about children?
Warn children to stay away from wild animals or stray pets.
Report bites or scratches to a physician.
How do I protect my pets against rabies?
Make sure your dogs and cats are vaccinated against rabies
every three years, or annually (depending on the vaccine used
by your vet).
At present, rabies vaccinations are compulsory in 31 of the
37 health units in Ontario. You could be fined if you do not
get your pet vaccinated against rabies.
Do not allow pets to wander freely, particularly at night,
when night-roamers like foxes, skunks, bats, and raccoons are
out.
Where can my pet get vaccinated and how much will it cost?
Contact your local veterinarian. The cost generally ranges
from $15.00 to $65.00. Vets may vaccinate your pet for other
diseases at the same time.
How long does the vaccination last?
A vaccination lasts either one or three years, depending on
the vaccine used by your vet.
When is a rabid dog or cat infectious?
Pets can transmit rabies once the virus is present in the
saliva. The rabies virus may be present in the saliva of an
infected dog or cat for a number of days before the onset of
visible signs. Once the signs occur, the animal usually dies |
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Which strains of rabies do I have to watch out for?
All strains are dangerous to pets, livestock and humans.
In recent years, most of the human deaths due to rabies have
been caused by bat strain rabies. From 1990 to 2004, over 75% (33
out of 43 cases) of all rabies deaths in Canada and the
United States have been caused by bat strain rabies. Most of
the non-bat strain rabies deaths (7 out of 10 cases) were acquired
while travelling outside of Canada or the United States. In many
of these rabies deaths due to bat strain rabies, the people were
not aware that they were bitten or in contact with a bat and did
not seek treatment until it was too late. In several instances,
people were in advance stages of rabies and were unable to
communicate with the doctor to indicate whether or not they had
been in contact with a bat.
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