1. Hans-Hermann Thulke & Dirk Eisinger Thomas Selhorst & Thomas Müller
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

2. Scope: Rabies-free region + naïve population
Conceptual frame – 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

3. Compact circle with 20 baits per km2
Conceptual frame – Alternative Ring – Alternative Dough – Conclusion
Strategy: Limited control area
Compact circle with 20 baits per km2
Unvaccinated area
Vaccinated area X X X
Increase
Rabies
detection
control area…
First I will show you the standard approach:
*After the detection of a case of rabies
*about 20 vaccine-filled baits per sqkm would be distributed in biannual campaigns in the immediate surrounding. The blue dotted area indicates the vaccinated area.
*To this standard scenario, called circle, we compared two alternatives, named ring scenario and dough scenario.
Target: Eradication + Avoiding breakout from control area

4. (Vaccinated area constant + number of baits equal + distance differs)
Conceptual frame – Alternative Ring – Alternative Dough – Conclusion 3
Alternative: Ring
(Vaccinated area constant + number of baits equal + distance differs)
CIRCLE
RING X X X X X X
I start with the ring scenario.
*Here we have again the circle scenario which immediate begins to fight the epidemic. In the ring scenario we have a different focus.
*In this scenario we use the resources from the inner area to add them outside, thus extending the radius.
In the circle scenario the epidemic might escape while the immunity is still being build up in the population, whereas the ring would still cover these cases due to the larger radius and since the epidemic needs more time to reach the inner skirts of the ring, the fox population would already being protected.
* In other words, the circle strategy is a combat strategy which immediately starts to fight the epidemic.
* Whereas the ring strategy is a containment strategy which primarily aims in protecting the susceptible surrounding due to the better cover and the fact that we have more time for the immunity being build-up.
COMBAT
CONTAIN

5. Simulation results: Circle vs. Ring
Conceptual frame – Alternative Ring – Alternative Dough – Conclusion ?
Simulation results: Circle vs. Ring
( repetitions)
RING
CIRCLE
Risk of Breakout
Time [campaigns]

6.    Ring design: Risk of breakout higher Strategy Economy
Conceptual frame – Alternative Ring – Alternative Dough – Conclusion
Ring design:
Strategy
Risk of breakout higher  
Economy
Public Health
Prolongation of measure
(inner part vaccinated later)
More cases of rabies
(inner part epidemic starts)

7. Eisinger et al. (2005) BMC Inf Dis 5:10
Conceptual frame – Alternative 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?

8. DOUGH CIRCLE Alternative: Bait density X X COMBAT COVER Focused COMBAT
Conceptual frame – Alternative Ring – Alternative Dough – Conclusion
Alternative: Bait density
(Immediate combat + Number of baits equal + vaccinated area differs)
CIRCLE
DOUGH
20 baits per km2
10 baits per km2
40 baits per km2 X X X
Now to the dough strategy
*Here we have again the standard scenario which in which 20 baits per sqkm gets distributed. In the alternative we deal area versus bait density. We can think of the vaccinated area as being a dough.
*We can stretch it, thus having a larger area to the cost of a lower bait density or squeeze it which results in a smaller area with a higher bait density.
* So the first we can call a cover strategy which gives a a much larger area, however due to the lower bait density, it will need much more time for the immunity build-up.
* The second is a fast combat strategy. Due to the high bait density we will get high immunity levels soon, however, due to the small area the danger of a misplacement of the vaccinated area is higher and in case we don’t get the epidemic stopped soon a breakout will be inevitable.
COMBAT
COVER
Focused COMBAT

9. _ _ ? + Simulation results: Area vs. density Risk of Breakout [%]
Conceptual frame – Alternative Ring – Alternative Dough – Conclusion
Simulation results: Area vs. density ?
( repetitions)
Risk of Breakout [%] _ _ +
 Dough thinner … Dough thicker 

10. Dough design by: Strategy slightly thinner advantageous
Conceptual frame – Alternative Ring – Alternative Dough – Conclusion
Dough design by: Strategy
slightly thinner advantageous
Economy
Public Health
The thicker the quicker is eradication
The thicker the fewer rabies cases

11.   ? Conclusion Model-based pre-testing helpful
Conceptual frame – Alternative Ring – Alternative Dough – Conclusion
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 ?  X  x

12. Thank you

13. Scenario deduction – Model description – Scenario evaluation – Conclusion & outlook5
Evaluation of relative performance of alternative scenarios
 Simulation experiment
Model Description
To do test these scenarios we developed a stochastic simulation model. I won’t say much about the model here. It is published in BMC Infectious diseases and available free online, so anyone interested in details is invited to have a look there.
Here I only say that the model consists of there modules. The first models the biology of the fox population, the second the transmission of rabies and the last the vaccination of foxes via baits.

14. Simulation model – Rule based
Scenario deduction – Model description – Scenario evaluation – Conclusion & outlook
Simulation model – Rule based
Model realisation
Population
Individual foxes
(Position & age, sex & disease state)
Seasonality
Reproduction in spring
Dispersal in autumn
suscept.
infected
infectious
empty
Spatial organization
Fox families in grid cells
To do test these scenarios we developed a stochastic simulation model. I won’t say much about the model here. It is published in BMC Infectious diseases and available free online, so anyone interested in details is invited to have a look there.
Here I only say that the model consists of there modules. The first models the biology of the fox population, the second the transmission of rabies and the last the vaccination of foxes via baits.
i.e.
Sayers et al. 1985

15. Model rules :: Biology Individuals: Subadults:
Scenario deduction – Model description – Scenario evaluation – Conclusion & outlook
Model rules :: Biology
To do test these scenarios we developed a stochastic simulation model. I won’t say much about the model here. It is published in BMC Infectious diseases and available free online, so anyone interested in details is invited to have a look there.
Here I only say that the model consists of there modules. The first models the biology of the fox population, the second the transmission of rabies and the last the vaccination of foxes via baits.
Individuals:
Mortality
Reproduction
Bait uptake
Subadults:
Dispersal

16. Neighborhood contacts
Scenario deduction – Model description – Scenario evaluation – Conclusion & outlook
Model rules :: Rabies transmission
To do test these scenarios we developed a stochastic simulation model. I won’t say much about the model here. It is published in BMC Infectious diseases and available free online, so anyone interested in details is invited to have a look there.
Here I only say that the model consists of there modules. The first models the biology of the fox population, the second the transmission of rabies and the last the vaccination of foxes via baits.
Neighborhood contacts

17. Neighborhood contacts
Scenario deduction – Model description – Scenario evaluation – Conclusion & outlook
Model rules :: Rabies transmission
To do test these scenarios we developed a stochastic simulation model. I won’t say much about the model here. It is published in BMC Infectious diseases and available free online, so anyone interested in details is invited to have a look there.
Here I only say that the model consists of there modules. The first models the biology of the fox population, the second the transmission of rabies and the last the vaccination of foxes via baits.
Neighborhood contacts
Mating activity
Dispersal

18. Model rules :: Bait distribution
Scenario deduction – Model description – Scenario evaluation – Conclusion & outlook
Model rules :: Bait distribution
baits/km2 (Spring & Atumn campaigns)
Spatial assignment to fox families
Bait competition
Individual bait uptake
To do test these scenarios we developed a stochastic simulation model. I won’t say much about the model here. It is published in BMC Infectious diseases and available free online, so anyone interested in details is invited to have a look there.
Here I only say that the model consists of there modules. The first models the biology of the fox population, the second the transmission of rabies and the last the vaccination of foxes via baits.