The Rural Voice, 1978-10, Page 34two years of life, then suddenly abort their
first calf.
l'he usual incubation period from the
time the animal comes in contact with the
bacteria until it can be detected in a blood
test, is about six months. That's why herds
suspected of brucellosis infection are kept
under quarantine for at least six months.
There is no cure for brucellosis and
vaccination is not an effective weapon in
the current Canadian situation where the
disease incidence is very low.
In addition, antibodies produced by the
vaccine may later be mistaken for those
produced by the actual disease, and this in
turn could result in the animal having to be
slaughtered.
"The only fool -proof method of detecting
the disease is to isolate the bacteria." says
Dr. L'Ecuyer. "But this is very difficult.
We have to take up to 20 tissue samples
from various parts of the cow. then try to
grow the bacteria in a culture. It's a
painstaking and dangerous procedure. Two
technicians can do only eight to 10 such
thorough tests per week."
Dr. L'Ecuyer, who until recently was
director of the Animal Diseases Research
Institute (East) says the bacteriological
tests are now being used to evaluate the
effectiveness of the four types of blood
tests performed by the Branch.
The tube agglutination test is the official
test. It is slow, taking 48 hours to complete.
r-
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With the Health of Animals Branch
Laboratories performing about three
million blood tests for brucellosis this year.
time is an important factor.
Also widely used is the rapid plate
agglutination test. Here, a highly concen-
trated antigen is added to the blood
sample. If there are brucella antibodies in
the serum, a visible reaction takes place.
These tests are very sensitive. but they
are not 100 per cent specific. They may
detect antibodies to other organisms that
are similar to brucella.
In some parts of Canada. cattle are given
a card test at auction barns.
"The card test is fast, and has been veru
useful in the field," Dr. L'Ecuyer says.
However, the test is almost too sensitive.
It can't distinguish between antibodies
from an earlier vaccination and the actual
disease. It may also show reactions to
bacteria which share some of the brucella
organism's properties.
The fourth type of test used by the
Branch is called complement fixation. This
is a two-stage test which is both sensitive
and specific. However, it is technically
demanding. expensive to perform and is
usually used to confirm other types of
tests.
Dr. L'Ecuyer says the current research
on brucellosis bacteriology should help tell
veterinarians which combination of tests
produces the most accurate results.
PG. 34 THE RURAL VOICE/OCTOBER 1978
He notes that as brucellosis is system-
atically detected and the positive reactors
are destroyed, there is a danger that
people in the industry will again become
complacent about the disease.
"The closer we get to eradicating the
disease, the tougher we will have to be. If
we relax the controls, the disease is bound
to start spreading again."
Drainage still needed
Almost three million hectares of land in
eastern Canada still require tile drainage,
says Max Colwell, a research economist at
Agriculture Canada's research station at
Harrow, Ontario.
Dr. Colwell estimates that 60 per cent of
improved farmland in Quebec, and more
than 40 per cent in Ontario could benefit
from improved drainage,
He notes in a recent issue of Canadian
Farm Economics that, while the rate of tile
drainage installation has increased since
1170. it would still take about 40 years in
Ontario and 50 years in Quebec to provide
the drainage needed.
The potential benefits are great, he
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