Epidemiology of brucellosis in ruminants: the basics and dynamics of the disease
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Transcript of Epidemiology of brucellosis in ruminants: the basics and dynamics of the disease
Epidemiology of Brucellosis in Ruminants: the Basics and Dynamics of the Disease
Professor John B. KaneeneDVM, MPH, PhD, FAES
Center for Comparative EpidemiologyMichigan State University
Workshop: An Integrated Approach to Controlling Brucellosis in Africa, Addis Ababa,
29-31 January 2013
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Basic Epidemiology of Brucellosis Reservoirs and Routes of Transmission Outbreak Investigations Surveillance and Control Programs Summary
Presentation Outline
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Host-Agent-Environment Host species: most mammals
Hoofstock: cattle, goats, sheepSwine and other mammals
Agents: Brucella spp.Host preferences, but not specific
Environmental conditions:Allows direct contact with materials contaminated
when Brucella are shed
Basic Epidemiology of Brucellosis
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Reservoir hosts:Host allows pathogen to survive, grow, and
multiply without compromising significantly reproduction and survival
Maintains infection within their species population
Capable of transmitting infection to other species
Reservoirs of Brucellosis
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Wildlife Reservoir of Brucella in Africa
Primary Livestock Reservoirs of Brucella
Reservoirs of Brucellosis
B. abortus:Cattle, Buffalo
B. melitensisGoatsSheep
B. abortus:African Buffalo
B. ovisSheep
B. suisSwine
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Brucella in Africa Wildlife
Reservoirs of Brucellosis
Bovidae*African buffalo*BushbuckEland ImpalaKobLechwe
Bovidae (cont).WaterbuckWildebeeste
Others: GiraffeZebraHippopotamus
* - high potential for reservoir status
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Primary Routes of Shedding for Brucellosis Urogential system
Uterine discharges: HIGHLY INFECTIOUS MilkSemen
Shedding not constant, consistent
Routes of Transmission
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Routes of Transmission for Brucellosis Ingestion of contaminated materialsContact through
Mucous membranes Open woundsConjunctiva
Vertical transmission – questionable
Routes of Transmission
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SheddingAbortion – reproductive fluidsMilk
After abortionContinue through life of the animal
Transmission Ingestion of milk Ingestion of contaminated materials
Maintenance of Brucellosis
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Steps for conducting outbreak investigationsEstablish and verify existence of outbreak
Reported casesRoutine surveillance
Define and identify casesConsistent case definitionLaboratory confirmation
Outbreak Investigations
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Steps for conducting outbreak investigationsEpidemiological Investigation
Data collection: demographics, clinical data, risk factors
Examination of cases and premisesCharacterize outbreak
Populations affected Geographic extent Dates and Trends over Time
Outbreak Investigations
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Steps for conducting outbreak investigationsFormulate & evaluate hypotheses
Source of infection Primary case Imported cases
Modes of Transmission and Exposures ‘Abortion storms’ Venereal exposure
Outbreak Investigations
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Outbreak ControlControl measures
Control source of pathogen – Identify infected animalsInterrupt transmission – Quarantine, cullingControl host response to exposure – vaccination
Monitoring to evaluate effectiveness of control measures
Directed Surveillance Passive and Active Surveillance
Outbreak Investigations
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1. Brucella spp. have many domestic and wildlife reservoirs
2. Outbreak Investigation is an important tool for studying disease dynamics
Summary
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3. Establishing surveillance systems is a key to monitoring disease status and planning for control measures
4. In both outbreak investigation and surveillance, use of appropriate diagnostic tests is critical
Summary (cont.)
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THANK YOU!