Further Reading (Brucellosis)
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Brucellosis Information from the Centers for Disease Control (USA)
www.cdc.gov/ncidod/dbmd/diseaseinfo/brucellosis_g.htm
Contents
General Information
Technical Information
Additional Information
General Information
What is brucellosis?
Brucellosis is an infectious disease caused by
the bacteria of the genus Brucella. These bacteria are primarily
passed among animals, and they cause disease in many different vertebrates.
Various Brucella species affect sheep, goats, cattle, deer, elk,
pigs, dogs, and several other animals. Humans become infected by
coming in contact with animals or animal products that are contaminated
with these bacteria. In humans brucellosis can cause a range of
symptoms that are similar to the flu and may include fever, sweats,
headaches, back pains, and physical weakness. Sever infections of
the central nervous systems or lining of the heart may occur. Brucellosis
cab also cause long-lasting or chronic symptoms that include recurrent
fevers, joint pain, and fatigue.
How common is brucellosis?
Brucellosis is not very common in the United States,
where100 to 200 cases occur each year. But brucellosis can be very
common in countries where animal disease control programs have not
reduced the amount of disease among animals.
Where is brucellosis usually found?
Although brucellosis can be found worldwide, it
is more common in countries that do not have good standardized and
effective public health and domestic animal health programs. Areas
currently listed as high risk are the Mediterranean Basin (Portugal,
Spain, Southern France, Italy, Greece, Turkey, North Africa), South
and Central America, Eastern Europe, Asia, Africa, the Caribbean,
and the Middle East. Unpasteurized cheeses, sometimes called "village
cheeses," from these areas may represent a particular risk
for tourists.
How is brucellosis transmitted to humans, and who is likely to
become infected?
Humans are generally infected in one of three
ways: eating or drinking something that is contaminated with Brucella,
breathing in the organism (inhalation), or having the bacteria enter
the body through skin wounds. The most common way to be infected
is by eating or drinking contaminated milk products. When sheep,
goats, cows, or camels are infected, their milk is contaminated
with the bacteria. If the milk is not pasteurized, these bacteria
can be transmitted to persons who drink the milk or eat cheeses
made it. Inhalation of Brucella organisms is not a common route
of infection, but it can be a significant hazard for people in certain
occupations, such as those working in laboratories where the organism
is cultured. Inhalation is often responsible for a significant percentage
of cases in abattoir employees. Contamination of skin wounds may
be a problem for persons working in slaughterhouses or meat packing
plants or for veterinarians. Hunters may be infected through skin
wounds or by accidentally ingesting the bacteria after cleaning
deer, elk, moose, or wild pigs that they have killed.
Can brucellosis be spread from person to person?
Direct person-to-person spread of brucellosis
is extremely rare. Mothers who are breast-feeding may transmit the
infection to their infants. Sexual transmission has also been reported.
For both sexual and breast-feeding transmission, if the infant or
person at risk is treated for brucellosis, their risk of becoming
infected will probably be eliminated within 3 days. Although uncommon,
transmission may also occur via contaminated tissue transplantation.
Is there a way to prevent infection?
Yes. Do not consume unpasteurized milk, cheese,
or ice cream while traveling. If you are not sure that the dairy
product is pasteurized, don't eat it. Hunters and animal herdsman
should use rubber gloves when handling viscera of animals. There
is no vaccine available for humans.
My dog has been diagnosed with brucellosis. Is that a risk or
me?
B. canis is the species of Brucella species that
can infect dogs. This species has occasionally been transmitted
to humans, but the vast majority of dog infections do not result
in human illness. Although veterinarians exposed to blood of infected
animals are at risk, pet owners are not considered to be at risk
for infection. This is partly because it is unlikely that they will
come in contact with blood, semen, or placenta of the dog. The bacteria
may be cleared from the animal within a few days of treatment; however
re-infection is common and some animal body fluids may be infectious
for weeks. Immunocompromised persons (cancer patients, HIV-infected
individuals, or transplantation patients) should not handle dogs
known to be infected with B. canis.
How is brucellosis diagnosed?
Brucellosis is diagnosed in a laboratory by finding
Brucella organisms in samples of blood or bone marrow. Also, blood
tests can be done to detect antibodies against the bacteria. If
this method is used, two blood samples should be collected 2 weeks
apart.
Is there a treatment for brucellosis?
Yes, but treatment can be difficult. Doctors can
prescribe effective antibiotics. Usually, doxycycline and rifampin
are used in combination for 6 weeks to prevent reoccuring infection.
Depending on the timing of treatment and severity of illness, recovery
may take a few weeks to several months. Mortality is low (<2%),
and is usually associated with endocarditis.
I am a veterinarian, and I recently accidentally jabbed myself
with the animal vaccine (RB-51 or B-19, or REV-1) while I was vaccinating
cows (or sheep, goats). What do I need to do?
These are live vaccines, and B-19 is known to
cause disease in humans. Although we know less about the other vaccines,
the recommendations are the same. You should see a health care provider.
A baseline blood sample should be collected for testing for antibodies.
We recommend that you take antibiotics (doxycycline and rifampin
for B-19 and REV-1, or doxycycline alone for RB-51) for 3 weeks.
At the end of that time you should be rechecked and a second blood
sample should be collected. (The sample can also be collected at
2 weeks.) The same recommendations hold true for spraying vaccine
in the eyes (6 weeks of treatment in this case) or spraying onto
open wounds on the skin.
Technical Information
Clinical Features
Extremely variable. In the acute form (<8 weeks
from illness onset), symptomatic, nonspecific and "flu-like,"
including fever, sweats, malaise, anorexia, headache, myalgia, and
back pain. In the undulant form (<1 year from illness onset),
symptoms include undulant fevers, arthritis, and orchiepididymitis
in males. Neurologic symptoms may occur acutely in up to 5% of cases.
In the chronic form (>1 year from onset), symptoms may include
chronic fatigue syndrome-like, depressive episodes, and arthritis.
Etiologic Agent
Brucella species, usually B. abortus (cattle),
B. melitensis, B.ovis (sheep, and goats), B. suis (pigs), and rarely
B. canis (dogs).
Incidence
In the United States, < 0.5 cases per 100,000
population. Most cases are reported from California, Florida, Texas,
and Virginia.
Sequelae
Extremely variable, including granulomatous hepatitis,
peripheral arthritis, spondylitis, anemia, leukopenia, thrombocytopenia,
meningitis, uveitis, optic neuritis, papilledema, and endocarditis.
Transmission
Zoonotic. Commonly transmitted through abrasions
of the skin from handling infected mammals. In the United States,
occurs more frequently by ingesting contaminated milk and dairy
products. Highly infectious in the laboratory via aerosolization;
cultures are considered to warrant biosafety level-3 precautions.
Risk Groups
Abattoir workers, meat inspectors, animal handlers,
veterinarians, and laboratorians.
Surveillance
Brucellosis is a nationally notifiable disease
and reportable to the local health authority.
Trends
For previous 10 years, approximately 100 cases
per year have been reported.
Challenges
Elimination of domestic and feral animal reservoirs.
Develop a serologic test to detect infection by a recently introduced
new live B. abortus vaccine (RB-51).
Opportunities
Identify, transfer to CDC laboratories, test,
and improve as needed, rapid diagnostic technologies developed for
identification of Brucella spp. for bioterrorism preparedness.
Additional Information
MMWR Articles
CDC. Human Exposure to Brucella abortus Strain
RB51--Kansas, 1997. MMWR
March 47:172-174
References
CDC. Human exposure to Brucella abortus strain
RB51–Kansas, 1997.MMWR 1998;47:172-175.
US Department of Agriculture, Agricultural Research
Service National Animal Disease Center, Iowa State University, Stevens,
M G, Olsen SC, Palmer MV, Cheville NF. Brucella abortus strain RB51:
A new brucellosis vaccine for cattle. Compendium 1997; 19:766-774.
Baldi PC, Miguel SE, Fossati, CA, Wallach JC.
Serological follow-up of human brucellosis by measuring IgG Antibodies
to lipoplysaccharide and cytoplasmic proteins of Brucella species.
Clin Infect Dis 1996; 22:446-455.
Martin-Mazuelos E, Nogales MC, Florez C, Gomez-Mateos
M, Lozano F, Sanchez A. Outbreak of Brucella melitensis among microbiology
laboratory workers. J Clin Microbiol 1994; 32: 2035-2036.
Khuri-bulos NA, Doud AH, Azab SM. Treatment of
childhood brucellosis: results of a prospective trial on 113 children.
Pediatr Infect Dis J 1993; 12:377-381.
Chomel BB, DeBess EE, Mangiamele DM, Reilly KF,
Farver TB, Sun RK, Barrett LR. Changing trends in the epidemiology
of human brucellosis in California from 1973 to 1992: a shift toward
foodborne transmission. J Infect Dis 1994; 170:1216-1223.
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