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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
Ann LindbergSwedish Dairy Association
Countrywide eradication ofBVDV – how can it be done?
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
Outline
Background
Systematic control in Europe
The Swedish BVDV scheme
– Strategy in non-infected herds
– Strategy in infected herds – Biosecurity
– Future challenges
Cost-benefit of control
Predictors for positive progress
General model for BVDV control
Summary
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
Background
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
Strategies for BVDV control –
”the old differentiation” Immunization(vaccination)
Avoiding exposure(zoo-sanitary approach)
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
Non-systematic control approaches
vs
Systematic control approaches
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
Systematic control
Goal-oriented, systematic reduction inthe incidence and prevalence of BVDV
infection Implies that progress is being
monitored
Scale – sectoral/regional/national Typically based on the ”avoiding
exposure” approach
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
Non-systematic control
Measures implemented on aherd-to-herd decision basis
Typically immunisation strategies
using live or killed vaccines
and/or removal of PI animals inselected cohorts withoutsystematic follow-up
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
Systematiccontrol in Europe
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
Density of bovines
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
Prevalenceof herds with
(any)
antibodies inbulk milk
Initialscreenings
1%
77%37%
95%
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
Prevalence ofherds withantibody levels
in bulk milkindicative of
recent/ongoingBVDV infection
1993
<1%
40%7%
40%
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
Scandinavian schemes
Schemes on BVDVlaunched in ’93-’94.
Goal =>eradication
Vaccines havenot been and
are notavailable
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
General outline of the
schemes Use herd level tests (test strategies) for
screening of herds with unknown status and
for monitoring of free herds Similar general strategy
– Establish probable herd status
– Monitor non-infected herds (antibodies)
– Clear infected herds from the infection
– Biosecurity framework controlling contacts / movements of animals between herds
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
Prevalence of herds underinvestigation 1993-2005
0
2
4
6
810
12
14
16
18
1 9 9 3
1 9 9 4
1 9 9 5
1 9 9 6
1 9 9 7
1 9 9 8
1 9 9 9
2 0 0 0
2 0 0 1
2 0 0 2
2 0 0 3
2 0 0 4
2 0 0 5
Year
I n f e c t e d h e
r d s ( % )
SE
DKNO
FI
0.01%
0.77%
0.01%
0.26%
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
The SwedishBVDV scheme
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
Why eradication?
TB eradicated during the 60s
Long term control of salmonella in the
farm animal sector National eradication scheme on
enzootic bovine leukosis 1990-2000
Low prevalent IBR eradicated during1995-1998.
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
Sufficientresources
Pieces that fell in place..
Gooddiagnostics
Financialsolution
Motivation
Goodunderstanding of the
epidemiology
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
Organisation Launched in September 1993.
Coordinated by Field work is organised mainly through 8
regional livestock cooperatives
Financed by farmers’ fees and by subsidies fromthe Board of Agriculture
Affiliation – Voluntary: 1993-1997 60% (D-93%; B-27%)
– Industry demand: 1997 (dairy), 1999 (beef)88% (D-100%; B-77%)
– Compulsory: 1 June 2002 (by law)
100%
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
Separation between non-infected- and infected herds
using herd level diagnostics
BULKMILK
BULKMILK
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
Strategy in non-infected herds
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
Screening/monitoring methods
BULKMILK
BULKMILK
5-10
5-10
1.
2.
3.
(7) 12 months
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
Certification
BULKMILK
7(12) months
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
No individual testing ofanimals in connection with..
..livestock trade
..common pastures
..exhibitions
..i.e. contact with animalsfrom other herds
Perishable goods…
BVDV-
free
Approved sample notolder than 3 months
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
Strategy ininfected herds
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
Infected herds
Systematic removal of
PI animals
Next presentation!
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
Biosecurity
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
Biosecurity?
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
Re-routing livestock trade
Demand for BVDV free cattle
Access to information on BVDV
status (all involved) Efficient diagnostic system (time
from sampling to status is availableminimised)
Rules and regulations
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
Other biosecurity measures
Direct contacts of all kind managed in the samemanner (based on a recent test)
Follow-up testing after potentially risky exposures Direct contacts with sheep/goats dealt with in a
similar way
Transportation staff should not enter cattleaccommodations
Visitors should be provided with clothes/boots to
borrow Double fencing towards adjacent farms
Follow-up testing after ET (imported embryos)
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
Future
challenges
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
Prevalence of herds with highlevels of antibodies in bulk milk
1993-2004
0
5
10
15
20
25
30
35
40
45
1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004
%
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
Future challenges
Continued import control – (livestock),embryos, semen
BVDV on the OIE agenda
Conclude the scheme!
Intensify work with herdclearances
Use available legislationto handle non-compliers
Regionalisation?
Molecularepidemiology fortracing sources of newinfections
Alternative ways tomonitor beef herds
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
Cost-benefit of control
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
Cost-benefit NorwegianBVDV programme (1993-2003)
Benefit estimated as expectedlosses – (avoided losses + cost
for control)
Norwegian conditions
Ref: Paul S. Valle, Norwegian School of Veterinary Sciences
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
Health and production losses
Effects of BVDV infection on:
Extra days open
Milk production
Culling
Animals lost/died
Treatments
Ref: Paul S. Valle, Norwegian School of Veterinary Sciences
C b fi N i
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
Cost-benefit NorwegianBVDV programme (1993-2003)
Ref: Paul S. Valle, Norwegian School of Veterinary Sciences
Estimated losses without control: 6.9million NZD/year
Cost-efficient already year 2
Benefit ~37.1 million NZD
(discounted value) over whole period
75% of all costs carried by the industry
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
Cost-benefit NorwegianBVDV programme (1993-2003)
-1000
0
1000
2000
3000
4000
5000
6000
7000
1993 1994 1995 1996 1997 1998 1999 2000 2001 2002
N
e t c a s h f l o w ( N Z D )
Ref: Paul S. Valle, Norwegian School of Veterinary Sciences
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
Predictors for progress
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
..intervene ininfected herds
Predictors for progress
..prevent new
infections
..rapidly
detect new casesof infection
..getacceptance of /
compliance withthe scheme
Ability to..
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
Ability to prevent new infections
Efficiency in means to protect free herds – change contact pattern – reduce risk associated with necessary
contacts
Efficiency in means to control infectedherds –
control movements from them – reduce the risk associated with being incontact with them.
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
Ability to rapidly detect new
cases of infection Efficiency of diagnostic procedures
– test performance
– test frequency
Efficiency in tracing sources of newinfections
Efficiency in the follow-up of herds that
have not re-confirmed their (free) status Access to subsidies on costs of
monitoring
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
Ability to intervene in infected herds
Efficiency of procedures aimed at clearingherds from the virus (diagnostics, logistics).
Strength in incentive to clear infected herds
– voluntary vs compulsory – strength of sanctions
Access to subsidies on costs for elimination of virus from infected herds
Access to compensation for slaughter of PI animals
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
Ability to get acceptance of /compliance with the scheme
Ability to communicate expected benefits ofcontrol
Extent of farmer involvement and awareness
Degree of involvement by farmers’ organizations(incl. industry support for sanctions)
Strength in support from authorities (legislation - juridical support for sanctions, subsidies)
Impact of market effects Presence of alternative financial solutions (e.g.
insurance)
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
Predictors for progress
time
Herd size and density
time
Initial prevalence
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
Predictors for progress
time
”Cumulative power”
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
The rate of progress of currentsystematic control schemes has notbeen a function of initial prevalence,herd density, herd size etc
It has been dependent on to whatextent they have been able to
develop these ”abilities”!
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
General model for BVDV control
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
BIOSECURITY
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
BIOSECURITY
VIRUS ELIMINATION
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
BIOSECURITY
MONITORING
VIRUS ELIMINATION
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
BIOSECURITY
IMMUNIZATION
VIRUS ELIMINATION
MONITORING
Advantages with zoosanitary
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
Advantages with zoosanitaryapproach
Easier to communicate importance ofbiosecurity
Does not convey a false sense of security
Risk of reinfection is rapidly reduced assoon as trade control is initiated
Easy to interpret diagnostics, possible to
use cheap screening methods
Future investments in monitoring are verylimited
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
If systematic reduction of BVDVprevalence is the goal:
Build the pyramid from thebottom…
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
Summary
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
Summary
The Nordic countries are facingeradication of BVDV, with reductions inprevalence from 40 to <1% in 11 yearstime.
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
Vaccines have not been used to protectsusceptible herds
A strong and instantaneous reduction inrisk of reinfection has been gained bylearning farmers to ask for BVDV freecattle..
Summary
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
Summary
The strategies chosen have been basedon the preconditions in each country
Progress more related to organisationand ability to take measures, than toinitial prevalence and herd size/density
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BVDV Summer Symposium, 7-8 March 2005, Wellington, New Zealand
Summary
A general model for systematic BVDV controlhas got three necessary steps:
Biosecurity, Virus elimination and Monitoring
Immunization is
– optional – adds a level of complexity
– ”advanced users only”