Conceptual frame – Alternative Ring – Alternative Dough – Conclusion
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Conceptual frame – Alternative Ring – Alternative Dough – Conclusion. Scenario-analysis evaluating emergency strategies after rabies re-introduction. Hans-Hermann Thulke & Dirk Eisinger Helmholtz Centre for Environmental Research UFZ :: Dept. of Ecological Modelling Leipzig/Germany.

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Conceptual frame – Alternative Ring – Alternative Dough – Conclusion

Scenario-analysis evaluating emergency strategies after rabies re-introduction

Hans-Hermann Thulke & Dirk Eisinger

Helmholtz Centre for Environmental Research UFZ :: Dept. of Ecological Modelling Leipzig/Germany

Thomas Selhorst & Thomas Müller

FLI Friedrich-Löffler-Institut :: Institute for Epidemiology Wusterhausen/Germany


Conceptual frame – Conclusion – Alternative Ring – Alternative Dough – Conclusion

Scope: Rabies-free region + naïve population

X

Large scale countrywide vaccination successful in past

  • here economically useless

Strategy: Limited control area


Conceptual frame – Conclusion – Alternative Ring – Alternative Dough – Conclusion

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Strategy: Limited control area

Unvaccinated area

Compact circle with 20 baits per km2

Vaccinated area

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Increase

Rabies

detection

control area…

Target: Eradication + Avoiding breakout from control area


Conceptual frame – – ConclusionAlternative Ring – Alternative Dough – Conclusion

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Alternative: Ring

(Vaccinated area constant + number of baits equal + distance differs)

CIRCLE

RING

X

X

CONTAIN

COMBAT


Conceptual frame – – ConclusionAlternative Ring – Alternative Dough – Conclusion

?

Simulation results: Circle vs. Ring

(10.000 repetitions)

RING

CIRCLE

Risk of Breakout

Time [campaigns]


– Conclusion

Conceptual frame – Alternative Ring – Alternative Dough – Conclusion

Ring design:

Strategy

Risk of breakout higher

Public Health

Economy

Prolongation of measure

(inner part vaccinated later)

More cases of rabies

(inner part epidemic starts)


Conceptual frame – – ConclusionAlternative Ring – Alternative Dough – Conclusion

Compact control area

around detection

is mandatory!

Eisinger et al. (2005) BMC Inf Dis 5:10

Emergency vaccination of rabies under limited resources – combating or containing?


Conceptual frame – Alternative Ring – – ConclusionAlternative Dough – Conclusion

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Alternative: Bait density

(Immediate combat + Number of baits equal + vaccinated area differs)

DOUGH

CIRCLE

20 baits per km2

40 baits per km2

10 baits per km2

COMBAT

Focused COMBAT

COVER


Conceptual frame – Alternative Ring – – ConclusionAlternative Dough – Conclusion

Simulation results: Area vs. density

?

(10.000 repetitions)

Risk of Breakout [%]

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_

+

 Dough thinner … Dough thicker 


Conceptual frame – Alternative Ring – – ConclusionAlternative Dough – Conclusion

Dough design by: Strategy

slightly thinner advantageous

Public Health

Economy

The thicker the fewer rabies cases

The thicker the quicker is eradication


Conceptual frame – Alternative Ring – Alternative Dough – Conclusion

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Conclusion

Model-based pre-testing helpful

  • Development and evaluation of alternatives

    Ring not applicable

  • Immediate combat of the outbreak is mandatory

    Lower bait density and larger area beneficial

  • Trading-off between success and control costs or rabies occurrence

    Need for further research!

  • Mixed application according to situation

?



Scenario deduction – – Model description – Scenario evaluation – Conclusion & outlook

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Evaluation of relative performance of alternative scenarios

 Simulation experiment

Model Description


Scenario deduction – – Model description – Scenario evaluation – Conclusion & outlook

suscept.

infected

infectious

empty

Simulation model – Rule based

Model realisation

Population

  • Individual foxes

    (Position & age, sex & disease state)

Seasonality

  • Reproduction in spring

  • Dispersal in autumn

Spatial organization

  • Fox families in grid cells

i.e.

Sayers et al. 1985


Scenario deduction – – Model description – Scenario evaluation – Conclusion & outlook

Model rules :: Biology

Individuals:

Mortality

Reproduction

Bait uptake

Subadults:

Dispersal


Scenario deduction – – Model description – Scenario evaluation – Conclusion & outlook

Model rules :: Rabies transmission

Neighborhood contacts


Scenario deduction – – Model description – Scenario evaluation – Conclusion & outlook

Model rules :: Rabies transmission

Dispersal

Neighborhood contacts

Mating activity


Scenario deduction – – Model description – Scenario evaluation – Conclusion & outlook

Model rules :: Bait distribution

  • 1 - 40 baits/km2 (Spring & Atumn campaigns)

  • Spatial assignment to fox families

  • Bait competition

  • Individual bait uptake


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