The Rural Voice, 1991-11, Page 24SHARING THE ENVIRONMENT,
SHARING THE DISEASE
BE WARY, SOMETIMES THE ANIMALS WE RAISE SHARE THEIR DISEASES WITH US
by Cathy Laird
h all started out with a small
blister-like spot on the little finger of
my left hand. I thought I had burned
myself on thc oven door, but there was
no fluid under the raised skin. One
week later, thc small mark had grown
to be the size of a nickel. It was raised
up a quarter of an inch and was the
colour of lilac flowers. Then, 1 deci-
ded to get to the doctor.
With one look, our doctor's wife
said that it looked like "orf." "Orf?" I
had never heard of it. I was told it was
a disease carried by sheep and goats,
and it can easily contracted by hand-
ling infected animals. We recently
had been given an orphan lamb, and
we all took turns feeding it.
About this time, our dog developed
two scab sores on his lower lip. Dogs
can get orf, too. Did I get orf from the
dog or thc Iamb? All I can say is that I
had orf and it was painful.
The disease was first called orf in
1890 by T. Walley. It is also known
as contagious pustular dermatosis in
humans, and as contagious ecthyma
in livestock. The disease is a skin -
infecting virus that is spread by direct
contact with infected animals and by
handling of contaminated equipment.
The disease contagious ecthyma is
found world-wide, and has been
documented exclusively in the white-
race of people. The age range of re-
ported cases has ranged from ten years
to 72 years. Certain groups of people
are more inclined to catch orf. Be-
sides animal producers, these groups
include veterinarians, people taking
immunosuppressive drugs, and people
with a tendency towards eczema.
The disease can be acquired
indirectly as well, because the virus
can be found on barn doors, on fences,
on feeding equipment, in bedding, in
manure, on towels, and in vehicles
used to transport livestock. The virus
has even been found on sheep pelts.
Contagious ecthyma is contracted
by sheep, goats, big horn sheep,
mountain goats, cattle, dogs, and
possibly cats. The animals do not
have to have visible sores on their
mouths to pass on the disease. Areas
that are particularly sensitive in sheep
are the mouth and lips, thus the names
"sorc mouth" and "scabby mouth" are
also used for the disease. In humans,
the primary areas of infection are the
hands and arms, particularly the right
index finger. High numbers of orf
disease occur on the right index finger
due to the finger being closest to the
mouth when feeding and handling the
animals.
In livestock, the sores usually start
at the corners of the mouth and spread
around the lips. Possible areas of
infection of feedlot lambs are mouth,
gums, tongue, palate, eyelids, and
middle ears. The eyelids, mouth, and
feet are affected primarily in nursing
SHAPES AND SIZES
OF TYPICAL VIRUSES
Bacterial virus
F2 or R17
•
20 nm
Polio virus
•
30 nm
Tobacco mosaic
virus
300 om�
Inllw.nia virus
•
80 nm
Herpesvirus
.-150 nm-.
The above illustration shows the
microscopic size of viruses. Much
smaller than the size of cells they infect,
they range in size from 20 to 400
nanometers. It takes about 25 million
nanometers to make up an inch.
Iambs. In breeding ewes and rams, the
skin and mucous membranes of the
genitals and the skin of the feet are
areas of sensitivity.
When contagious ecthyma is found
in the mouths of nursing lambs, kids,
and calves, the disease can spread to
the teats and udder of the milking
mothers. A complication of the dis-
ease in lactating animals is mastitis.
Contagious ecthyma in livestock
can spread to the gastro-intestinal
areas, as well as to the feet. The dis-
ease spreads quickly in a flock or
herd, with up to 90 per cent of the
animals in a single group having les-
ions or sores on the mouth. Rarely
does the disease lead to death, but sore
mouths reduce feed intake, leading to
general malaise and weakness, leading
to secondary illnesses, such as pneu-
monia.
The virus that causes orf is a
member of the DNA family Pox-
viridae, and resembles the virus of
sheep pox, vaccinia, and lumpy skin
disease. The sores are similar to "cow
pox" or "milker's pox" that was more
common years ago when milking was
done by hand.
The orf virus is sturdy, and can
survive over a cool winter on pasture
land, and can re -occur in a herd or
flock from year to year. The virus has
been known to survive at room tem-
perature for 15 years. Scabs can
"seed" an area with the live virus, but
lose their ability to cause infection in
the summer heat after 30 to 60 days.
Once livestock, dogs, or humans
contact the virus, there follows a
period of immunity ranging from one
to three years. The most common age
for lambs to be infected with conta-
gious ecthyma is one to three months
of age, but the disease commonly
occurs in lambs from three to six
months of age, also. There is no evi-
dence as yet that immunity can be
given through colostrum, although
annual vaccinations of pregnant ewes
20 THE RURAL VOICE