BRUCELLOSIS
Designed by-Dr. Lakhmir Sophia
OverviewOrganismHistoryEpidemiologyTransmissionDisease in HumansDisease in AnimalsPrevention and ControlActions to Take
DefinitionBacterial disease, infectiousHighly contagious zoonoticCaused by ingestion of unpasteurized
milkUndercooked meat from infected
animalsOr also with close contact with
infected animal
Brucella spp.Gram negative
coccobacillus◦Facultative,
intracellular organismMultiple species
◦Associated with certain hostsEnvironmental persistence
◦Withstands drying◦Temperature, pH, humidity◦Frozen and aborted materials, dust, soil
Species Biovar/Serovar
Natural Host Human Pathogen
B. abortus 1-6, 9 cattle, bison, buffalo yesB. melitensis 1-3 goats, sheep yesB. suis 1, 2, 3 swine yes
2 European hares yes4* reindeer, caribou yes5 rodents yes
B. canis none dogs, other canids yesB. ovis none sheep noB. neotomae none rodents noB. maris B. pinnipediae, B. cetaceae(?)
marine mammals yes?
The Many Names of Brucellosis
Human DiseaseMalta FeverUndulant FeverMediterranean FeverRock Fever of
GibraltarGastric Fever
Animal DiseaseBang’s DiseaseEnzootic AbortionEpizootic AbortionSlinking of CalvesRam EpididymitisContagious Abortion
History of Brucellosis450 BC: Described by Hippocrates1905: Introduced to the U.S1914: B. suis
◦Indiana, United States 1953: B. ovis
◦New Zealand, Australia1966: B. canis
◦Dogs, caribou, and reindeer
History of BrucellosisAlice Evans
◦American bacteriologist credited with linking the organisms in the 1920s
◦Discovered similar morphology and pathology between: Bang’s Bacterium abortus Bruce’s Micrococcus melitensis
Brucella nomenclature◦Credited to Sir David Bruce
Reported incidences1887- Spleen of patients(Brucella
mellitensis)1905- infection was traced in
goat’s milk1914- identification of Brucella
suis in pigs1950- Brucella ovis in rams1960- Brucella canis in dogs
EPIDEMIOLOGY
Populations at RiskOccupational disease
◦Cattle ranchers/dairy farmers◦Veterinarians ◦Abattoir workers◦Meat inspectors◦Lab workers
HuntersTravelersConsumers
◦Unpasteurized dairy products
Species of BacteriaBrucella mellitensisB. abortusB. suisB. ovisB. canis
TRANSMISSION
Transmission in HumansIngestion
◦Raw milk, unpasteurized dairy products
◦Rarely through undercooked meatMucous membrane or abraded
skin contact with infected tissues◦Animal abortion products
Vaginal discharge, aborted fetuses, placentas
Transmission in HumansAerosol
◦Laboratory, abattoirs◦Pens, stables, slaughter houses
Inoculation with vaccines◦B. abortus strain 19, RB-51 ◦B. melitensis Rev-1 ◦Conjunctival splashes, injection
Person-to-person transmission rare
Transmission in AnimalsIngestion of infected tissues or
body fluidsContact with infected tissues
or body fluids◦Mucous membranes, injections
Venereal◦Swine, sheep, goats, dogs
●Fomites
Pathogenesis Entry of organism by
ingestion
Localized in
regional lymph node
Enter into
intestinal
epithetial cellsEnter
lymphatics
Bactermia
Localize in reproductive organs, placenta,
fetus, mammary
glands, lymph nodes, spleen, liver, joints, bones.
Organism
proliferates
within the cells
Affinity of
bacteria to
placenta and focus esp.
chorio – allantoi
c trophobl
ast
Due to erythrit
ol in these tissue
Abortion
Brucella organism
Phagocytosis by
macrophages
Survive inside the
macrophages
Prevents fusion of lysosome with phagosomes
Bacteria not exposed to lysososmal enzymes
Bacteria grows inside
phagosomes of macrophages
Hence antibodies are in effective against bacteria
Macrophages rupture, release
the bacteria
Clinical Signs:Cattle and Bison
Third trimester abortions with B. abortus
Retained placenta◦Once expelled will have a
leathery appearanceEndometritisBirth of dead or weak calves
◦Respiratory distress and lung infections
Low milk yield
Clinical Signs: Sheep and Goats
B. melitensis ◦ Late term abortions
Retained placenta Birth of dead or
weak lambs/kidsGoats
◦ Articular, periarticular hygroma localizations
B. ovis◦ Abortions, fertility problems in sheep
Orchitis, epididymitis Abnormal breeding soundness exam
Clinical Signs: SwineB. suis
◦Prolonged bacteremia◦Abortion, early or late gestation◦Fertility problems◦Lameness, posterior
paralysis, spondylitis,metritis, abscesses
Clinical Signs: HorsesB. abortus most common
◦Susceptible to B. suisFistulous Withers or Poll Evil
◦Inflammation of the supraspinous bursa
◦Exudative process Bursal sac fills with clear
viscous liquid Can eventually rupture
Clinical Signs: DogsB. canis
◦Abortions Last trimester Prolonged
vaginal discharge◦Bacteremia◦Failure to conceive, stillbirths,
Prostatitis, epididymitisAlso susceptible to
◦B. melitensis, B. abortus, and B. suis
Clinical Signs: WildlifeElk
◦Abortion◦No retained placenta,
infertilityMoose
◦Debilitation, deathPredators act as vectors
◦Coyotes, crows, vultures, bears
Lesions Bacterial
granuloma in tissues, especially in lymphoreticular system.
No multinucleated giant cells. These ganulomas are visible grossly, or may be of microscopic size- classical lesion of Brucellosis
Gross lesionsNecrosis of cotyledons Inter – cotelydonary
chorion is oedematous and filled with odourless, sticky, brownish exudates
Yellowish granular, necrotic areas in colytedon.
Rest of chroion is opaque, thickened and leathery
Induration of bovine mammary glands and supramammary lymphnodes
Epidydimis and testicles of bulls become enlarged and hard
Scrotal contents – suppuration & rupture
Pigs Tiny white yellowish nodules in all
organs Rams Tail of epididymis a inflammed
Bitches Uterine and placental lesions Bronchopneumonia in aborted pups Osteomyelitis in dogs
Horses Necrotizing and purulent lesions in
ligamentum nuchae Necrotizing and purulent lesions in
region of thoracic attachment of ligamentum nuchae
Microscopic lesionsBovines
◦Organisms in chorionic epithelial cells ◦Necrosis and inflammatory exudates with
macrophages and neutrophils ◦Collection of epithelioid cells in endometrium.
Mammary gland ◦Diffuse inflammation, with lymphocytes and
neutrophils. ◦Collection of epithelioid cells with langhan’s
giant cells. ◦Later atrophy of glands and fibrosis
Pigs ◦ Typical Brucella
granulomas with necrosis Rams
◦ Perivascular oedema and lymphocytic infiltration
◦ Hyperplasia and degeneration of tubular epithelium and intertubular fibrosis
◦ Escape of spermatozoa from damaged tubules produced granulomatous response
Dogs ◦Hyperplasia and
plasmacytosis of lymphnodes
◦Orchitis ◦Epidydimitis ◦Prostatitis ◦Hyalinization of
glomeruli
Diagnosis in AnimalsIsolation of organism
◦Blood, semen, other tissuesSerology
◦Brucellosis card test, ELISABrucella milk ring testDemonstration by fluorescent
antibody of organism in clinical specimen◦Placenta, fetus
PREVENTION AND CONTROL
Prevention and ControlEducation about risk of
transmission◦Farmers, veterinarians, abattoir
workers, butchers, consumers, hunters
Wear proper attire if dealing with infected animals/tissues◦Gloves, masks, goggles
Avoid consumption of raw dairy products
Prevention and ControlImmunize in areas
of high prevalence◦Young goats and
sheep with Rev-1◦Calves with RB51 ◦No human vaccine
Eradicate reservoir ◦Identify, segregate,
and/or cull infected animals
Prevention and ControlB. suis, B. ovis, and B. canis
◦Venereal transmission◦Separate females at birthing to
reduce transmission on the farm or in kennel