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Q. What is Brucellosis?
A.
Brucellosis is a contagious disease caused by bacteria
called Brucella abortus. This disease infects domestic animals,
wildlife and humans worldwide. In the United States, the primary livestock
carriers of the disease historically have been cattle. The only wildlife
populations known to be infected with Brucella abortus in the United
States are the elk and bison in the Greater Yellowstone Area (GYA) of
Wyoming, Montana and Idaho. Some feral swine populations, and caribou and
reindeer in Alaska are known to be infected with a type of brucellosis
caused by a similar bacteria, Brucella
suis.
Although
rare, brucellosis can also infect humans and is called undulant fever, Malta
fever or Mediterranean fever. Once a person is infected, the disease can
affect any organ or organ system of the body.
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Q. How Do People or Animals Get
Brucellosis?
A. In ungulates (hoofed animals), such as cattle,
bison and elk, the animal becomes infected after ingesting or eating the
Brucella organism. The organism is shed in birthing tissues and fluids,
especially before, during or soon after an animal aborts or delivers live
young. An elk that encounters an aborted elk fetus will instinctively sniff,
lick and/or eat the infected reproductive tissues thus infecting itself.
People may become infected with brucellosis by coming in
contact with infected animals and their reproductive tissues. The bacteria
can enter the body through ingestion, contact with mucous membranes (e.g.
eyes), through an open wound, or rarely through intact skin. People who
drink unpasteurized milk, or eat other dairy products that are unpasteurized,
are at the highest risk for getting the disease. Other people at high risk
include livestock handlers, slaughter industry workers and veterinarians.
If properly cooked, meat from infected animals is
NOT a health risk to humans.
Infected bison and elk may be a health
risk for hunters who either improperly handle the carcasses or are exposed
to birth tissues. The risk is greatest when handling infected females during
their last half of pregnancy (e.g. February-June). There have been two
confirmed cases of hunters contracting undulant fever from elk in the
GYA, both in Madison County in southwest Montana.
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Q. What Are the Signs of Animals Infected
With Brucellosis?
A. In the field, elk and
bison usually do not show any obvious signs of having brucellosis. After an
animal becomes infected with the bacteria, the incubation time (the time
between exposure to the bacteria and the beginning of symptoms) varies
depending on how much exposure the animal had, whether or not they have been
previously vaccinated, the species, age, sex and stage of pregnancy.
Following a short infection, the bacteria usually collects in the udder
and/or lymphatic system and, depending on the stage of pregnancy, in
reproductive tissues. Abortion is a symptom of brucellosis. Other symptoms
include retained placenta, reduced milk production, weak calves, lameness,
swollen joints, swollen testicles and reduced ability of females to become
pregnant.
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Q. What Happens to People Infected With
Brucellosis?
A. People
infected with brucellosis can have many different symptoms such as weakness,
lethargy, anorexia, fatigue, body aches, sweats and mental inattention.
Other symptoms might include fever, swollen lymph nodes and occasionally an
enlarged liver and/or spleen. Symptoms usually begin 2-3 weeks after a
person becomes infected. In about one half of cases, the symptoms appear
right after infection, while in other cases, symptoms develop over several
weeks or months.
In people, brucellosis can affect any
organ or organ system. Bones and joints are commonly involved and the lower
spinal cord (the spine itself does not swell) often swells and is painful.
Infected people can also suffer from painful, swollen joints in the
shoulder, knees or hips. People rarely die from brucellosis. Life
threatening conditions include infection of the heart valves or the brain.
However, these cases are rare.
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Q. As a Big Game Hunter In
The GYA, How Can I Avoid Becoming Infected With Brucellosis?
A.
The chance of a hunter becoming infected with brucellosis is
very small, especially if he or she uses precautions, such as wearing
protective clothing and gloves, using care with sharp instruments and
washing thoroughly after
handling animal tissues.
It is important for hunters to
use gloves and other barriers when handling the
carcasses of bison or elk. Disposable latex gloves are cheap, easy to find
and easy to carry. They also make cleaning up after field dressing the
animal much easier. Latex gloves should be included in your bag of “hunting
essentials”.
In addition, when field dressing game, hunters should
prevent their open wounds or mucous membranes from coming into contact with
blood, reproductive tissues or other fluids from harvested game. Hunters
should also avoid handling the reproductive tract or fetuses. And, as a
general rule, hunters should not handle or eat animals that appear sick,
regardless of the cause.
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Q. What Is Being Done To
Prevent And Eliminate Brucellosis?
A.
Idaho, Montana and Wyoming are all committed to eliminating brucellosis from
their wildlife populations. Some of the ways that the states are trying to
deal with the disease include:
~ Vaccinating-
Vaccines are being tested on wild animals to determine how effective they
are in preventing animals from getting the disease. Elk are vaccinated in
Wyoming.
~ Habitat improvements-
By using prescribed burns and other habitat improvement techniques, state
and federal wildlife agencies are trying to improve the quality of habitat
along the summer/winter migration routes of elk. These improvements can
encourage elk to leave their winter ranges earlier and spread out from each
other. When elk are more spread out, they are less likely to be in contact
with aborted fetuses, which is a major
source of infection.
~ Separation of cattle
and elk during the winter-
Because most abortions occur during the winter and early spring, managers
try to keep cattle and wildlife separated during this time so that cattle do
not become infected. This helps prevent cattle from coming in contact with
aborted fetuses.
~
Increased agency cooperation and
public information and education-
In 1995, the Greater Yellowstone Interagency Brucellosis Committee was
formed. The committee is made up of several state and federal agencies that
deal with brucellosis issues. The Committee works to share up-to-date
research and management information between agencies and with the public.
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Q. Who Do I Contact If I
Have Additional Questions Or Concerns About Brucellosis?
A. The
Greater Yellowstone Interagency Brucellosis Committee’s
website has several related documents and links to other brucellosis sites:
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http://gyibc.com/
Additional information, regarding Brucellosis, is available through the
following agencies:
Idaho
Department of Fish and Game:
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http://www2.state.id.us/fishgame/fishgame.html
Montana
Fish, Wildlife and Parks:
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http://www.fwp.state.mt.us/
Wyoming Game
and Fish Department:
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http://gf.state.wy.us/
