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

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

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

(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

Simulation results: Circle vs. Ring Conceptual frame – Alternative Ring – Alternative Dough – Conclusion ? Simulation results: Circle vs. Ring (10.000 repetitions) RING CIRCLE Risk of Breakout Time [campaigns]

   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)

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?

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

_ _ ? + Simulation results: Area vs. density Risk of Breakout [%] Conceptual frame – Alternative Ring – Alternative Dough – Conclusion Simulation results: Area vs. density ? (10.000 repetitions) Risk of Breakout [%] _ _ +  Dough thinner … Dough thicker 

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

  ? 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

Thank you

Scenario deduction – Model description – Scenario evaluation – Conclusion & outlook 5 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.

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

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

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

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

Model rules :: Bait distribution 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 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.