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Use of Vaccines in a BVDV Control/Eradication Program

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Use of Vaccines in a BVDV Control/Eradication Program Steven R. Bolin, DVM, PhD Diagnostic Center for Population & Animal Health Michigan State University – PowerPoint PPT presentation

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Title: Use of Vaccines in a BVDV Control/Eradication Program


1
Use of Vaccines in a BVDV Control/Eradication
Program
  • Steven R. Bolin, DVM, PhD
  • Diagnostic Center for Population Animal Health
  • Michigan State University

2
Definitions
  • Disease control programs designed to reduce
    disease incidence, prevalence, morbidity or
    mortality to a locally acceptable level as a
    result of deliberate efforts continued
    intervention measures are required to maintain
    the reduction MMWR 48 (SU01) 23-27, 1999
  • Disease control prevent by any means
    transmission of disease from animal to animal

3
Successful disease control requires thorough
knowledge of the causal agent and the disease
cycle, host pathogen interactions, environmental
factors, and cost. Encyclopedia Britannica
4
Definitions
  • Disease eradication the permanent reduction of
    a diseases prevalence in a geographic area to
    zero
  • Indicators of eradicability keys to a possible
    successful outcome
  • an effective intervention is available
  • practical diagnostic tools exist that have the
    sensitivity and specificity to detect levels of
    infection that can lead to transmission
  • cattle are essential for the life-cycle of the
    agent
  • no other vertebrate host for the agent exists
  • agent does not amplify in the environment

5
Economic Considerations
  • Resources are limited
  • Resources cross sectors
  • Time, personnel, equipment, physical facilities,
    money
  • Are sufficient resources available to handle a
    disease control/eradication program?
  • Are sufficient resources left over to handle
    other existing issues?

6
Economic Considerations
  • Cost-effectiveness analysis
  • Comparison of the costs and effects of two or
    more courses of actions
  • Most useful when expressed in health termshow
    one disease compares with other diseases
  • Would herd health be better if disease A was
    controlled or if disease B was controlledwhat
    would it cost to control disease A or to control
    disease B?

7
  • Direct effects of a disease control/eradication
    program
  • Disease becomes rare or ceases to exist control
    measures may change or cease
  • Money is saved, herd health improves, market
    increases, value increases, profit increases
  • Consequent effects
  • Economic decline for somepharmaceutical
    biologics companies, diagnostic laboratories,
    veterinarians
  • Infrastructure decay
  • Other health issues emerge

8
Social / Political Considerations
  • Disease control, and especially disease
    eradication, depend on social and political
    commitment that likely must last for years
  • Available resources seldom allow more than a very
    limited number of control/eradication programs to
    occur simultaneously
  • Once the commitment is made to control a disease,
    failure to control or eradicate the disease will
    cause a loss of credibility for those who
    promoted the program (personal risk of failure)

9
BVD Control / Eradication
  • ? Know cause of BVD
  • ? Good working knowledge of BVDV
  • ? Good working knowledge of BVDV interactions
    with the hostmodes of transmission, duration of
    infection, duration of shedding, immune response
  • ? Effective interventionsbiosecurity, vaccine,
    and environmental controlremove PI cattle
  • ? Practical, sensitive and specific diagnostic
    tests serology, PCR, IHC, virus isolation

10
BVD Control / Eradication
  • ? Cattle are essential for the life cycle of BVDV
  • Sufficient resources are available for a BVDV
    control / eradication program
  • ? Local program
  • ? Small regional program
  • ? Large regional/national program
  • Sufficient resources will be left over to handle
    other health issues
  • BVDV is the most important/costly health problem
    for the cattle industry/for all animal health

11
Vaccination In Disease Control
  • Advantages of vaccination
  • Considered the most cost effective means for
    control of infectious disease in livestock
  • Rapid method for establishing the 80 herd
    immunity thought necessary for disease control
  • Vaccination helps control the impact of events
    that you can not control wildlife reservoir,
    hole in the fence, out of control neighbor
  • Testing helps control the impact from known risks
    introduction of new animals, going to fairs and
    shows

12
Vaccination in Disease Eradication
  • Advantages of vaccination
  • Rapid means for establishing herd immunity
  • Create zones of containment or create islands
    that are free of disease/free of agent
  • Spares resources until they become critically
    needed at the end of an eradication program

13
Vaccination in Disease Control/Eradication
  • Disadvantages of vaccination
  • May create a diagnostic dilemma with use of
    serology differentiate vaccinated from infected
    animals
  • Faster, more effective method for disease control
    is ignored Stamp out method
  • Production capacity for the vaccine may not be
    sufficient to meet the needs for vaccine usage
  • 40,000,000 doses needed to get 80 coverage and
    production capacity is only 5,000,000 doses

14
Vaccination in Disease Control/Eradication
  • Is a vaccine available?
  • Modified live-virus and inactivated-virus
    vaccines are available
  • Multiple viral isolates and both major serologic
    groups of BVDV represented in the vaccines
  • Are the vaccines effective?
  • Prevent harmful clinical disease yes
  • Prevent transmission of BVDV mostly

15
Vaccination in Disease Control/Eradication
  • Serologically differentiate vaccinated from
    infected animals in high throughput diagnostic
    testing no
  • Production capacity sufficient to meet needs ?
  • Resources available to administer vaccine ?
  • Will one dose of vaccine administered only once
    in the animals life prevent disease and prevent
    transmission of BVDV ? 2 doses? 3 doses?

16
Vaccination in Disease Control / Eradication of
BVDV
  • Are there other effective means for eradication
    of BVDV that might use less resources maybe
  • If we try to eradicate BVDV, and use vaccination
    as a primary tool, are we prepared to stop
    vaccinating and use stamp out?
  • If we try to eradicate BVDV, and do not use
    vaccination, are we prepared to use stamp out?

17
Vaccination for BVDV in a Control Program
  • Local-mix vaccination with biosecurity and
    testing
  • Regional - vaccinate at least 80 of animals in
    year one, only acquire vaccinated and tested
    animals
  • Vaccinate at least 80 of all calves (100 of all
    replacements) every year for 5 years
  • National - vaccinate at least 80 of animals
    within 2 years, only acquire vaccinated and
    tested animals
  • Vaccinate at least 80 of all calves (100 of all
    replacements) every year for 5 years

18
Vaccination for BVDV in a Control ProgramYear 6
  • Localcontinue mixing vaccination with
    biosecurity and testing
  • Regionalreassess prevalence of disease and
    agent, do what is needed
  • Nationalreassess prevalence of disease and
    agent, implement enhanced measures in trouble
    spots

19
Vaccination for BVDV in an Eradication Program
  • Local mix vaccination with biosecurity and
    testing
  • continued use of vaccination may be necessary to
    minimize effect of BVDV if it returns
  • Regional comprehensive use of vaccination
    probably necessary at the start of the program
  • perimeter vaccination may be necessary at the end
    of the program
  • National vaccination required, vaccine
    selection will be limited, testing will be
    controlled

20
Vaccination for BVDV in an Eradication Program
year 6
  • Localcontinue mixing vaccination with
    biosecurity and testing
  • Regionalvaccination over except for the
    perimeter of the region (maybe), availability
    of live virus is controlled
  • Nationalvaccination over, vaccines not
    available, laboratory strains of virus not
    available, serologic testing restricted to
    national lab, indemnification

21
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