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What are the direct diagnostic strategies? (4)
- isolation (culture)
- nucleic acid detection (PCR)
- antigen detection (ELISA)
- direct visualization (microscopy)
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What is the indirect diagnostic strategy?
antibody detection
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What is the difference between prevention and control?
- prevention: steps taken to lower the risk of infection before the agent is present in the population
- control: measures taken to lower the risk of exposure and frequency of infection and decrease the severity of disease once the agent is in the population; reduce impact of dz to a tolerable level
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What is the difference between elimination, eradication, and extinction?
- elimination: reduction to zero of the incidence of infection caused by an agent in a defined geographical area as a result of deliberate efforts.
- eradication: permanent reduction to zero of the worldwide incidence of infection caused by a specific agent as a result of deliberate efforts; intervention measures no longer needed
- extinction: specific infectious agent no longer exists in nature or in the laboratory
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What is required for justification for prevention/ control/ eradication (P/C/E) programs? (3)
- potential impact on public health
- potential impact on animal health and animal welfare
- economic impact
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What are agent factors in the epidemiological triad? (5)
range, resistance, affinity, dose, mode of transmission
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What are host factors in the epidemiological triad? (3)
species, age, immune/nutritional status
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What are environmental factors in the epidemiological triad? (4)
housing, care, weather, vector presence
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What are the categories of P/C/E programs? (4)
- compulsory govt-run programs
- voluntary govt-run programs under state authority and/ or federal authority
- voluntary private or cooperative programs
- private programs for individual farms or small groups of related units
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What are strategies for prevention? (6)
- population integrity (closed herd)
- biosecurity
- national animal health programs
- active disease surveillance
- trade regulations
- quarantine and testing
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What are strategies for control? (5)
- management practices- environmental conditions, nutrition, genetics
- biosecurity
- vaccination
- prophylaxis
- treatment
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What are the necessary conditions for eradication? (5)
- an effective diagnostic test
- an effective method for destruction of the agent in reservoirs (or destruction of reservoirs themselves)
- a small host range
- a limited spectrum of disseminating mechanisms
- acceptability to the industry
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What are the 5 methods of eradication?
- test and remove
- depopulate
- treatment
- vaccination
- do nothing else
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Describe the test and remove method of eradication?
- testing all animals, removing all animals identified as carrying the disease
- relies on diagnostic tests to detect exposed/ carrier animals (no test is 100% sensitive or specific; you don't want to leave a positive in the population-- go for the most sensitive test possible!)
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What are the limiting factors of the test and remove method of eradication? (4)
- percentage of animals involved initially should be low (otherwise, might as well just depop)
- amount of disruption to the economy
- availability of replacement animals
- sensitivity and specificity of diagnostic test
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Describe the depopulation method of eradication?
- elimination of diseased animals and all animals in contact with them
- used for fast spreading diseases and high-consequence diseases that are not tolerated in our population
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When is the depopulation method of eradication considered? (2)
- an affected population cannot be tested and carry out selective slaughter
- test and remove is not cost effective when infection is spreading too rapidly to cope with otherwise
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When is treatment used as an eradication method?
the txt must be very effective in killing the agent
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Describe the vaccination method of eradication.
vaccinate all animals (or susceptibles) in the population--> reduction of clinical signs, reduction of carriage, reduction of dz transmission, reduction of antibiotic usage
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What are the properties of the ideal vaccine? (6)
- cost-effective
- immunogenic
- long lasting immunity
- safe
- stable easy administration
- differentiation of infected from vaccinated animals
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What is the first step to any method of eradication?
stop movement of animals
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