The Rural Voice, 1990-06, Page 30ported in Ontario. Of these, well
over 90 per cent occurred in southern
Ontario. In fact, more than 70 per
cent of the rabies cases in Canada
occur in southern Ontario.
Cases of human exposure to rabies
rise and fall with the prevalence of the
disease in animals —10 to 15 per cent
more humans will be treated for ex-
posure than there are animal rabies
cases reported.
Rabies cases by animal group
Cattle 12%
Cat 6%
Dog 3%
4%
Other
domestic
Other wildlife 4"6
Skunk 26%
Fox 45%
In the past 10 years, says Dr.
Charles Le Ber, senior veterinary
consultant for the Ontario Ministry of
Health, an average of 2,500 to 3,000
humans have been treated annually
for exposure to rabies.
Given the rarity of human death
by rabies, medical scientists speculate
about the possibility of some human
resistance to the strain of the disease
in Ontario. "It really makes you
wonder," says Dr. Le Ber. "But
because it is fatal, we must take
these precautions."
These precautions, in fact, may
largely account for the rarity of human
infection. The post -exposure treat-
ment for humans is a series of injec-
tions: 5 intramuscular injections on
days 0, 3, 7, 14, and 28. Formerly,
treatment called for 21 injections.
Since 1982, the rabies vaccine has
been of human origin, which mini-
mizes the allergic reactions associated
with the older vaccines, which were
produced from the tissue of mouse
brain, then from duck embryo tissue.
The modem vaccine is a "human
diploid cell vaccine" and is grown in
normal human embryo lung (fibro-
blast) cell tissue. It produces an anti-
body reaction 10 to 20 times greater
than the older vaccines. Many veter-
inarians have regular vaccinations to
minimize the risk of handling animals.
This pre -exposure vaccine entails
three injections and a booster about
every two years.
The control of rabies is achieved
by creating and maintaining an "im-
mune barrier" between domestic
animals and wildlife. The control of
wild animals, with their varied migra-
tion patterns, is next to impossible. So
individuals must focus on immuniza-
tion programs for pets and attempt to
isolate pets from other animals.
People are also discouraged from
keeping wild animals as pets. In one
case, a raccoon exposed 150 people to
the rabies virus, of whom 74 were
treated for the disease. The ratio of
rabies in wild animals compared to
domestic pets is 3 to 1. There are no
vaccines that have been approved for
use with domesticated wildlife animal
pets.
Various attempts to immunize
wildlife have been tried. Bait poison-
ing, sterilizing hormones, and the gas-
sing of animals in dens were attempt-
ed. Besides being inhumane, the
methods were largely ineffective.
Animal rabies cases by county
1989-90
Huron 87
Perth 50
Grey 135
Bruce 22
Recently, feed has been baited with
vaccine. The Ministry of Natural
Resources reports this reached 74 per
cent of foxes, 56 per cent of skunks,
and 85 per cent of coyotes.
Baiting was done in the province
from aircraft that could "seed" 200
square miles with 90 baits per square
mile in less than 8 hours. The baits
contained tetracycline as an antibiotic.
The tetracycline was used as a "bio -
marker," showing up on teeth and
indicating how often and when the
animal was in contact with the bait.
Hunters and trappers helped the
MNR by providing information and
animal specimens for examination
and research.
First aid for handling animal bites
(and always assume the presence of
–rabies!) entails four steps:
1. Wash the area immediately
and thoroughly with soap and water.
This is especially important with a
puncture -type wound;
2. Apply an antiseptic. Alcohol is
effective in cleaning the wound site;
3. Consult a medical doctor.
Usually a tetanus injection is admin-
istered;
4. Notify the Health Unit and
provide information to assist in
locating the animal., If destroying the
animal, try not to damage the brain.
Human exposure to animal groups
Dog
30%
Other
domestic 7%
Cat 19%
`�Skunk 4°/,
Cattle 15%
Other
wildlife
11%
Fox 14%
"The virus can be killed on the
surface," notes Dr. Moore. "It is very
susceptible to alcohol and other dis-
infectants. There are very few human
fatalities."
The response when a pet or farm
animal comes into contact with a rabid
animal involves five steps:
1. Isolate the pet and prevent
further contact with the rabid animal;
2. Contact a veterinarian;
3. Report the incident to the
district office of Agriculture Canada's
Food Production and Inspection
Branch;
4. Vaccinated animals may be
quarantined three to six months;
5. Unvaccinated animals may have
to be destroyed.
Rabies is under constant study,
and testing methods have improved
dramatically. Today, fast and accurate
fluorescent antibody tests are used on
fresh brain tissue. "The specimen,"
says Dr. Moore, "is dyed to show the
rabies virus cells. The test is 98 per
cent accurate and the results can be
obtained in one day. New procedures
now let the test be performed on tissue
samples with hair from live animals."
Rabies is a serious, unpredictable
disease. "There are different signs in
all animals," Moore says. "It is safest
to assume the presence of rabies until
we know for sure."0
26 THE RURAL VOICE