BRUCELLOSIS

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BRUCELLOSIS
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Brucellosis is also known as Bangs
Disease. Brucellosis is known as a contagious
abortion disease in animals. In humans, the
disease is known as Malta fever, Mediterranean
fever, and undulant fever. The disease is named
after Sir David Bruce, an English army surgeon
who identified the cause of the disease in 1887.
Sir David Bruce found the causative agent to be
Bacillus melitensis. He found the bacteria in
the spleens of British soldiers who died of
undulant fever on the Mediterranean island of
Malta. Several years later the infection in
these British soldiers was traced to the
soldiers drinking contaminated goats milk.
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In 1897, Brucella abortus was isolated and
identified from an aborted bovine fetus by Danish
veterinarian, Dr. Fredrick Bang. The infection
in cattle became known as Bangs disease and was
eventually proven to be ubiquitous in many
animals. Brucellosis is one of the most serious
diseases of livestock because of the damage it
causes decreased milk production weight
loss loss of young infertility lameness
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Note Brucella spp. Was the first microbe that
the United States chose to develop as a
biological weapon The reasons it was chosen,
include its ease of manufacture, susceptibility
to sunlight and its ability to be spread by
aerosol dispersion or by contaminated food or
milk. It has the advantage of being
debilitating to people without being fatal. Its
development as a biological weapon was stopped in
1967, and later President Nixon banned
development of all biological weapons on November
25, 1969.
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Causative Agent (Pathogen) A contagious
bacterial disease Br. abortus cattle and
bison Br. suis swine Br.
canis dogs Br. melitensis sheep and goats
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Brucellosis only occasionally affects horses and
cats are relatively resistant to the infections.
Depending upon how an animal contracts
brucellosis, a different species of Brucella may
be causing the infection. For example pigs,
sheep and goats that are in contact with infected
cattle can be infected with Br.
abortus. Dogs that ingest placentas from
farm animals may be infected with Br.
abortus, Br. susis, and Br. melitensis.
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Brucella spp. Are a gram negative coccobacilli
( rods that are so short that they resemble
cocci ) The bacteria infect the placenta, uterus
and fetus, causing abortion in females. It also
infects the testes and accessory sex glands
causing orchitis and accessory sex gland
infection in males. It can cause infertility in
both sexes. Br. Abortus and Br. Canis cause
mild disease in humans, whereas Br. Suis and Br.
Melitensis can be fatal.
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Brucellosis has a worldwide distribution and can
affect a variety of animals. In the United
States and Europe brucellosis is uncommon as a
result of its elimination from cattle herds. Br.
melitensis in sheep and goats represents
the most important source of brucellosis
in humans it is not enzootic in the United
States, Canada, northern Europe,
Australia, or Souteast Asia prevalent in
Latin American, Mediterranean area, Central
Asia and the countries around the Arabian Gulf.
Humans are infected by the handling of
animals during the birthing process and
the consumption of raw milk products
(especially fresh soft cheeses)
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Br. suis affects both sexes of swine
causes infertility, abortion, orchitis,
bone/joint lesions prevalence is generally
low occurs in areas in which pigs are kept,
including southeastern United States and
Australia where populations of feral swine
are heavily infected. Human infections
occur in people handling pigs on farms and during
slaughtering and processing feral and
domestic swine.
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Br. abortus has been eradicated from Canada,
Japan, northern Europe and Australia
Cases in humans are sporadic and are acquired by
drinking unpasteurized milk working with
infected cattle at a slaughter facility by
attending infected parturient cattle accidental
inoculation with live vaccine
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Br. Canis infection in humans tends to occur
in dog handlers In the United States, the
frequency of brucellosis is related to the number
of infected animals. Infected animals are rare
in the United States and pasteurization of milk
has eliminated that mode of transmission Occupati
onal exposure (cattle-workers, veterinarians,
slaughterhouse workers) is the main transmission
route in the United states. The incidence is
approximately 200 cases per year. People with
Brucellosis in the United States are primarily
found in Texas, California, Virginia and Florida

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Pathogenesis Once in the body, Brucella spp. are
engulfed by neutrophils and are carried In the
lymphatic fluid to the lymph nodes draining the
infected area. The infected neutrophils release
bacteria into the blood and bacteria localize in
certain organs. liver spleen bone
marrow kidney The gross lesions seen in an
animal are subtle and rarely diagnostic.
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In cows, placental lesions include edema
necrosis brownish odorless discharge In
aborted bovine fetuses edema bronchopneu
monia In bulls scrotum becomes enlarged
and thickened
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In swine formation of white nodules on the
uterus of females formation of white nodules on
the testes of males lesions in both sexes of
the spleen, liver, kidney, lymph nodes and
bone In sheep edema and inflammation of the
epididymis in rams necrosis of the placenta in
ewes inflammatory changes in the lung, liver,
lymph nodes spleen and kidneys of lambs
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In dogs uterine and placental lesions in
females orchitis in males bronchopneumonia in
pups The incubation period of brucellosis is
variable ranging from 2 weeks to 1 year or
longer. Note the typical length is 30 to 60
days.
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Diagnosis in Animals Tissues infected with
Brucella spp. do not provide distinctive
findings. Diagnosis in animals consists of
bacteriologic or serologic identification.
Treatment in Animals Treatment of infected
animals is not attempted because animals may
recover from the disease signs but do not clear
the infection. Management and Control in
Animals Measures for prevention and control of
brucellosis include vaccination of calves,
periodic testing of bulk milk from farms, blood
testing of adults and slaughtering of infected
animals.
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In the United States a federal program for
brucellosis eradication called the Cooperative
State Federal Brucellosis Eradication Program has
existed since 1934. States are deemed
brucellosis free when none of their cattle or
bison is found to be infected for 12 consecutive
month under an active surveillance program.
Clinical Signs in Humans Brucella spp. are
able to establish an infection by surviving
phagocytosis and are passed from the lymph to
blood and then to organs throughout the
body. The organs mainly affected are the liver,
spleen, and bone marrow. In humans the
incubation period is typically 5 to 60 days (or
longer)
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The most prominent symptoms are weakness
loss of appetite chills headache
back pain intermittent (undulating)
fever It persists for weeks to months if left
untreated. Chronic infection can damage joints
and the spinal cord.
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Diagnosis in Humans Diagnosis is primarily
dependent on clinical suspicion adequ
ate history of possible exposure
(including travel) isolation of the
organism Brucellosis in humans is very hard to
diagnose. An undeniable diagnosis requires
isolation of the organism using blood culture as
the method of choice. Culture from bone marrow,
blood and affected organs may be successful.
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Treatment in Humans Humans are treated with
antibiotic combinations for 4 to 6 weeks. No
widely accepted vaccines for humans have been
developed. All material taken directly
from Understanding Zoonotic Diseases by Janet
Amundson Romich published by Thomson/Delmar
Learning.