Preventing CSF re-emergence:
a continuous challenge
Dr Frank Koenen
CODA-CERVA-VAR
CSF characteristics
Virus characteristics
Small enveloped RNA virus
Member of Genus pestivirus with BVDV and BDV
Disease characteristics
Clinical picture has changed from acute to sub-acute or even subclinical
An isolate can induce different clinical pictures
Last 20 years only sporadic epidemics
in domestic pigs (EU 15)
Economical impact
Economic and socio-economic impact is very high worldwide.
1993-94 epidemic: 21.4 millon € for outbreaks and 130 million € for
market support
1997 epidemic: 10 million pigs
slaughtered, total costs 1 billion €
2006: small outbreak: 120.000 pigs
culled
Detection-Monitoring- Intervention strategy
Detection:
Clinical detection can be difficult
Laboratory detection:
• IF, VI, ELISA, real time PCR
Monitoring:
Sampling schemes are available
Intervention strategy:
Modified live vaccine (C-strain)
Sub-unit marker vaccine
Stamping out
High risk period (HRP) High risk period (HRP)
Country Year Estimated HRP-1 (weeks)
United Kingdom 1986 4
The Netherlands 1997 6
Belgium 1993 3
Germany 1997 8
Spain 1997 9
Elbers
Elbers et al., 1999et al., 1999
Introduction - Transmission
In contrast to an unknown emerging disease a lot of information is available.
Factors and circumstances affecting introduction:
• Animal trade, including import of wildlife
• Geographical proximity
• Tourists
• Hunters
• Tourist-illegal import of food
• Swill
Factors influencing spread and transmission:
• Oro-Nasal contact
• Animal transport
• Intense trade (no vertical structure)
• High pig density (air?)
• Semen
• People
• Poor hygiene and lack of biosecurity
Will CSF re-emerge?
Pr ob ab ly y es !
Why?
Why?
Historical cycle:
9 years
Presence worldwide
Changing factors
CSF in the world
CSF in Europe
Changing factors
Farming and trading system
Contact structures
Wildlife management
Geo political decisions influencing trade structures
Increased awareness of bio
security
CSF in Wild boar
Wild boar population
Population increased dramatically during the last decades
Wild boar density is recognised as one of the most relevant risk factors for CSF
80% of the first outbreaks of CSF in
domestic pigs in regions where CSF is
endemic in Wild boar
Oral vaccination with C-strain
CSF control strategies in wild boar
Hunting
Unclear strategy When? Before or after outbreak?
Where? Which region?
Frequency? Once, multiple?
Backyard pigs
Freerange:
Pigs spend the day looking for food (cultivated corn, bulbs, fruit-trees, garbage) and water
When they come back home in the morning they are feeded with a small portion of corn or waste.
Backyard pigs
Important economical factor in new member states.
Home consumption: from 1 to 15 pigs. It is a production for family consumption and usually it consists of one pig or, in the best cases, two sows with their piglets.
Small producers: from 16 to 40 pigs. It is a production for the family consumption and to sell the leftovers..
Backyard pigs
Sanitary status:
CSF is endemic
Asymptomatic carriers (CSF, PRRS)
Reservoirs of parasitic, zoonotic diseases
Management:
Not individually identified
Any kind of registration
No possibility to measure birth, mortality or morbidity rates
Vaccination program:
Not all the individuals in the population are vaccinated.
How to avoid
re-emergence?
Increase knowledge
Decrease HRP
Database
Mathematical disease spread models Mathematical disease spread models can provide appropriate tools for:
can provide appropriate tools for:
Disease vigilanceDisease vigilance
Evaluating control optionsEvaluating control options
• • Estimate the number of infected farms after a Estimate the number of infected farms after a CSF introduction
CSF introduction
• • Estimate the effect of different herd types on Estimate the effect of different herd types on disease spread
disease spread
• • Make predictions about the expected Make predictions about the expected geographical distribution of infections geographical distribution of infections
Live marker vaccine
Decrease HRP
Personal Digital Assistant (PDA) with data-entry screen (Elbers)
Improve early detection:
Education
Hand computer
Data transfer
Intake of data in e- mail message by Computer-server at University of Utrecht
GPRS
Data in e-mail
attachment sent by PDA via Internet
Calculation of CSF-probability on PC (in future on PDA)
Possibility for sending back CSF- probability to practitioner within minutes after
receiving clinical data
Farm
Central CSF Data Base Central CSF Data Base
(data, questionnaires, web server)
Laboratories Departments
Districts
Ministries (BMVEL) Scientific Institutes Competent „Land“ Authorities
Ministries
Departments Districts
Age Virolo gy
Virus Vaccina tion
Serolo gy
EU Data base
2004
Domestic pigs: 0 Wild boar: 3
Domestic pigs: 11 Wild boar: 451 2002
Follow up of CSF
Ribbens and Dewulf
Modelling
’ ’
Ribbens and Dewulf
Results-’hobby’
Ribbens and Dewulf
Results-’regular’
Ribbens and Dewulf
Results-’High contact’
Wild boar Management: Hunting
Wild boar Management: Vaccination (20%)
Wild boar Management: vaccination (40%)
In a single population with < 1000 to 1500 wild boar:
ÆThe disease will fade out.
Random interaction Hunting + Vaccination:
Æ Endemic evolution in 4% of the cases
Conclusions CSF management in wild boar
Optimal vaccination condition:
Start vaccination at 150 days after virus infection Immunize at least 40% of all susceptible animals
Hunting should NOT exceed 45% of the whole population
Live Marker Vaccine development
New candidate selected for application in wild boar
Several other chimera and back up available
Æ Possibility to study vaccine characteristics
Evaluation towards vaccine:
Formulation of the product as a vaccine for oral application
Safety studies
Potency studies
Onset of immunity
Conclusions
Known agent:
Preparedness in order to limit the HRP:
• Education
• Monitoring
• Real time exercise
But!
Situation changes
New threats
Available tools change or can be adapted
Research:
Improve existing tools
Develop new tools
Update the knowledge concerning environmental changes
