Brucellosis

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