brucellosis in cattle, sheep & goats: fundamentals of
TRANSCRIPT
Brucellosis in Cattle, Sheep & Goats:
Fundamentals of surveillance and eradication programs
B. Garin-BastujiEU / OIE & FAO Reference Laboratory for Brucellosis
ANSES – Maisons-Alfort, France
Thailand-Japan Conference on Animal HealthThe 25th Year Anniversary of National Institute of Animal Health
Rama Gardens Hotel, Bangkok, ThailandMay 30-31, 2012
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Bovine brucellosisNever reported EradicatedInfected Reported in the past
Data not available
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Sheep & Goats brucellosisNever reported EradicatedInfected country Reported in the past
Data not available
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Porcine BrucellosisNever reported
Infected countries
Infection reported in the past
Data not available
5
Human brucellosis global incidence
Incidence <2/millionIncidence >2/million Data not available
Incidence >50/million
Epidemiology & diagnosis of Brucellosis….
�Key elementsfor a sound strategy…
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Epidemiology of Brucellosis….
�Brucellosis is a "multi-species"infectious disease…
� different animal species� different Brucella species
…..to be considered
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B. melitensis
B. abortus
B. suis
Wild Ruminants, Rodents, Carnivores
Swine
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�Cattle, sheep, goats or pigs,.. …and wildlife
� frequently in contact…in many areas
Epidemiology of Brucellosis….
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Epidemiology of Brucellosis
�Abortion is the main sign of brucellosis…
�But, most infected females give birth normally ...
�In both cases, huge and durable excretion of Brucella
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�Survival of Brucella out of their host is long (compared with most other non-sporing pathogenic bacteria, under suitable conditions)
� Brucella may survive on / in many materials
Epidemiology of Brucellosis
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�Brucella are excreted primarily in:– Abortion & normal birth materials
– Vaginal secretions– Semen
– Milk and colostrum
Epidemiology of Brucellosis
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Entry point Mucous membranes & skinConjunctivae, nasopharynx & respiratory tract, oral route, genitalia
�Vertical transmission (in utero): congenital infection
�Horizontal transmission– Direct
Infected aerosolsConsumption (or licking) of infected materials and milkContactSexual transmission
– Indirect (water, manure, materials, shoes,...)
Epidemiology of Brucellosis
Transmission (in animals)
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Neighbouring /transhumance
Purchase
Resurgence(partial depopulation)
Transmission away(Water, manure, materials, shoes, vehicles)
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Epidemiology of Brucellosis….
�Epidemiology of Brucellosis is complex…
�Lots of transmission routes, most of them being almost impossible to control…
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Diagnosis of Brucellosis….
�No single test able to…– identify all infected animals, or
– certify all free animals
�Tests repetitions needed
�Tests associations (parallel/series), modify considerably the results predictive values (-ve/+ve)
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Diagnosis of Brucellosis
�Serological tests– Early,sensitive but low specificity (RBT/FPA))– Sensitive but low specificty (iELISA)– Late, more specific but less sensitive (CFT)– Highly specific but lower sensitivity (cELISA)– Highly sensitive/specific (iELISA on milk, but..)≠ tests: ≠ antibodies detected
�Cell tests: BST (highly specific, but..)
� Frequent discrepancies between tests� Associations usually needed� Predictive values (-ve/+ve) linked to prevalence.
� Choice of tests and interpretation should always be based on epidemiological reality.
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Epidemiology & diagnosis of Brucellosis….
�Brucellosis is a herd/flock disease…
– the epidemiological unit is the herd , the flock or the group including all epidemiologically-related sensitive animals
– the individual prevalence has no significancefor control monitoring
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Brucellosis Control /eradication strategies ….
�Tools &strategies…
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Control/elimination of animal brucellosis: the tools
�Test and isolation/slaughter– Partial or full depopulation
� Control of animal movements� Vaccination
…and adequate– Political will– Budget– Vet. Services / Lab. infrastructure– Animal/herd identification– Good quality vaccines
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Vaccination (Rev.1 & S19)�Vaccination increases resistance to infection and decreases
abortion risk– Thus, decreases the spread of infection– Thus, decreases individual and herd/flock prevalence– Thus, decreases incidence in human populations– But,
� insufficient on its own to eradicate� vaccine-induced serological/cell-immune reactions
�Sub-cutaneous or conjunctival route at standard dose– Cattle (females): S19
• 3-6 months SC 5-10x1010 CFU/dose
• Adults SC 0.3-3x109 CFU/dose (non pregnant, lactating or late pregnancy)
• Both CR 5-10x109 CFU/dose (twice)
– Sheep & Goats: Rev.1• 3-6 months SC 0.5-2x109 CFU/dose
• Both CR 0.5-2x109 CFU/dose (non pregnant, lactating or late pregnancy)
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RB51 Vaccine in Cattle (Moriyon et al. Vet. Res. 2004)
• Sub-cutaneous route (10-30 x109/ dose)• Increasingly used in place of S19• Effectiveness is much debated• Experiments and field trials:
– Some better than S19– Other:
• reduced doses: ineffective• full doses: only partially effective• or RB51 less effective than S19 against severe
challenges.• other observations suggest that RB51 is ineffective
when prevalence is high. • RB51 is not useful in sheep and evidence in goats is
preliminary and contradictory. • Azores: effective only when vaccine coverage and
eradication scheme fully & duly appliedThailand-Japan Conference on Animal Health -25 th Anniversary of NIAH, Bangkok, Thailand - May 30-31, 2012 22
Brucellosis Control /eradication strategies ….
�Which tools…Which strategy…
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Preliminary considerations
The epidemiological situation is almost never homogeneous in a given country/region
Different epidemiological / livestock contextswithin a country/region
�
Different & adaptedcontrol / eradication strategies
to be implemented�
Primary goals of a control programme:Knowledge of situation & definition of Epidemiological units of intervention
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Strategy / objectives
� First objective in endemic areas� Control of the infection
� Final objective � Eradication
� Mid / short-term objective �Regularly decrease the prevalence
�Progressive strategy
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Decision tree for brucellosis control in animals
test/slaughterCombined young animal
vaccination and test/slaughter
high prevalence Intermediate prevalence Low prevalence
Is brucellosis present in a certain area/country?
Yes
Are there adequate means / expertise / vet. services?
Mass vaccination
NoYes (survey/prevalence/epidemiological units)
NoSurveillance/test-and-slaughter/
movement control
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In conclusion….
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Control, surveillance & Eradication of Brucellosis…
�Epidemiology is the main key…– A sound knowledge of the situation is required before
deciding of a strategy– Adequate epidemiological parameters are required for
evaluating the results and monitoring the program…– Changes in strategy should always be based on
epidemiological evidences
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Control, surveillance & Eradication of Brucellosis…
�Diagnosis is the 2nd key…– Tests associations (series or parallel)
� to increase the result predictive values
– Test result interpretation…always in relation with: • risk-factors• status of the herd, the area, the country
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Don’t forget the iceberg!
Diagnostic testsVaccines
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Thanks for your attention…
Acknowledgments: Dr. Anastasios MINAS (Greece) for the Brucellosis Global status maps
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