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Redirected page to Category:Brucella species
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#REDIRECT[[:Category:Brucella species]]
 
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{{toplink
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|backcolour =
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|linkpage =Bacteria
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|linktext =BACTERIA
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|pagetype=Bugs
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<br>
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===Overview===
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*Important zoonoses worldwide
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*Cause chronic granulomatous diseases
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*6 species
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*Target reproductive organs of certain species
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*Infected animals act as reservoir of infection
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*Organisms can remain viable in moist environment for months
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*Cause undulant fever in humans
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===Characteristics===
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*Small, non-moltile, Gram negative coccobacilli
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*Facultative intracellular pathogens
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*Modified Ziehl-Neelsen positive - clusters of red coccobacilli on smears
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*Aerobic and capnophilic
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*Catalase positive; oxidase and urease positive except for ''Brucella ovis'' 
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*Some species require enriched media for growth
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*Non-haemolytic
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*Smooth colonies of ''B. abortus, B. melitensis'' and ''B. suis'' are small, glistening, blue and translucent after incubation for 3-5 days, and become opaque with age
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*Rough colonies of ''B. ovis'' and ''B. canis'' are dull, yellow, opaque and friable
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*Slide agglutination with speicific antisera detect important antigens
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*''B. abortus'' lysed by specific bacterophages
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*Oxidative metaboloic rates can differentiate species
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===Pathogenesis and pathogenicity===
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*Brucellae that lack outer membrane LPS (rough colonies) are less virulent than those which possess it
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*Penetrate nasal, oral or pharyngeal mucosa
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*Phagocytosed and carried to regional lymph nodes
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*Smooth organisms survive and multiply in cells of the reticulo-endothelial system
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*Inhibit lysosome-phagosome fusion
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*Superoxide dismutase and catalase production may resist oxidative killing
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*Lymph nodes enlarge (lymphatic and lymphoreticular hyperplasia) and inflammation is induced
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*Surviving organisms spread to other organs (liver, [[Spleen - Anatomy & Physiology|spleen]], placenta) and cause granulomatous reactions
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*Eythritol is a growth stimulant and attracts the bacteria to the placenta of cattle, sheep, goats and pigs; also found in mammary gland and epididymis, targets for brucellae
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*Infection of foetus and abortion
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*May localise in joints or intervertebral discs in chronic infections
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===Clinical disease===
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*Bovine brucellosis:
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**Caused by ''Brucella abortus''
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**Eradicated in many countries including UK
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**Infection usually by ingestions but also venereal, skin abrasions, inhalation, transplacental
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**Abortion storms in susceptible herds
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**Abortion after fifth month of gestation due to placentitis
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**Brucellae excreted in foetal fluids for 2-4 weeks following abortion and at subsequent parturitions without abortion
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**Infection of mammary glands and lymph nodes persists for years
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**Excreted intermittently in milk for years
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**Seminal vesicles, ampullae, testicles and epididymus infected in bulls; necrotising orchitis
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**Decreased fertility in cows and bulls; decreased milk production
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**Localisation in [[Spleen - Anatomy & Physiology|spleen]] and lymphatic tissue of non-pregnant animals
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**Occasionally causes [[Joints Inflammatory - Pathology#In Cattle|arthritis]]
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*Isolated from closed cases of [[Bursae and Tendons Inflammatory - Pathology#Poll Evil and Fistulous Withers|poll evil and fistulous withers]] in horses
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*Caprine and ovine brucellosis:
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**Caused by ''B. melitensis''
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**Goats more susceptible
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**Abortion, orchitis in males, arthritis, hygromas
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**May not have protective immunity following abortion
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**Rose Bengal agglutination test and complement fixation test
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**Test and slaughter where exotic
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*Ovine epididymitis
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**Caused by ''B. ovis''
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**Epididymitis in rams and placentitis in ewes
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**Reduced fertility in rams, sporadic abortion and peinatal mortality
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**Venereal transmission
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**Long latent period in rams following infection (present in semen 5 weeks after infection)
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**Premating checks on rams - serological tests and scrotal palpation
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**Testicular atrophy and swollen epididymis in chronically-infected rams
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**Agar gel immunodiffusion test, complement fixation test and indirect ELISA
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**Vaccination of young rams with ''B. melitensis'' vaccine or ''B. ovis'' bacterin
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*Porcine brucellosis:
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**Caused by ''B. suis''
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**Prolonged bacteraemia
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**Chronic inflammation in reproductive organs of boars and sows; also in joints and bones
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**Routes of infection: ingestion or venereal
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**Abortion, still birth, neonatal mortality, temporary sterility
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**Boars excreting bacteria in semen may have testicular abnormalities or be normal
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**Lameness, incoordination and posterior paralysis in joint and bone involvement
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**Rose Bengal and indirect ELISA for diagnosis
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**Test and slaughter where exotic
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**Modified live ''B. suis'' vaccine
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*Canine brucellosis:
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**Caused by ''B. canis''
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**Rough therefore lower virulence - mild or asymptomatic infections
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**Abortions, decreased fertility, reduced litter sizes, neonatal mortality
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**Orchitis and epididymitis causing infertility in male dogs
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**Infertility may be permanent if chronic infection
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**Slide agglutination, ELISA, agar gel immunodiffusion
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**Neuter infected animals
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*Human brucellosis:
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**Susceptible to ''B. abortus, B. suis, B. melitensis'' and ''B. canis''
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**Transmission via contact with secretions from infected animals
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**Routes of infection: skin abrasions, inhalation, ingestion
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**Unpasteurised milk source of infection
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**Undulant fever - fluctuating pyrexia, malaise, fatigue, muscle and joint pains, osteomyelitis
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**Can become chronic
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**''B melitensis'' and ''B. suis'' cause most severe infections
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**Antimicrobials
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===Diagnosis===
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*Serological testing of milk (Milk Ring Test) and beef cattle (Rose Bengal Plate Test)
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*Serological tests detect anti-lipopolysaccharide antibodies
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*LPS antigen present in virulent as well as some vaccine strains therefore vaccination may confuse serological testing
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*False positives due to cross-reaction with LPS in other bacteria
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*Modified Ziehl-Neelson stains reveal organisms in samples from cotyledons, uterine discharge and foetal abomasal contents
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*PCR for detection in tissue
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*Brucellin for intradermal testing for ''B. abortus''
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*Enriched media for isolation
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*Complement fixation test
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*Indirect and competitive ELISA
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*Serum agglutination test
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*Antiglobulin test
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===Control===
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*Test and slaughter program has eradicated bovine brucellosis in the UK
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*Vaccination of heifers against ''B. abortus'' in endemic regions:
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**Strain S19, a live attenuated vaccine, stimulating a cell-mediated immune response; vaccination of young animals; interferes with serological testing
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**45/20 bacterin vaccine less effective
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**Newer RB51 vaccine has no LPS O-antigen therefore not detected by serological tests and gives good protection
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*Live attenuated ''Brucella melitensis'' vaccine to protect lambs and kids against ''B. melitensis''
 
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