THE STRENGHT OF 70%THE STRENGHT OF 70%

REVISING A GIVEN THRESHOLD OF RABIES CONTROLREVISING A GIVEN THRESHOLD OF RABIES CONTROL

THE STRENGHT OF 70%THE STRENGHT OF 70%

REVISING A GIVEN THRESHOLD OF RABIES CONTROLREVISING A GIVEN THRESHOLD OF RABIES CONTROL

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1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002

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Tollwut Suveillance Data

UFZ - Project group Ecological Epidemiology

EcoEpi

Leipzig

Modell

The strength of The strength of

70%70%

The strength of The strength of

70%70%

Eradication

~ 70%

Europe

Persistence

Anderson et al. (1981). Population dynamics of fox rabies in Europe. Nature 289: 765-770

The strength of 70%The strength of 70%The strength of 70%The strength of 70%

The strength of 70%The strength of 70%The strength of 70%The strength of 70%

Eradication

~ 70%

Europe

Persistence

Eradication Eradication

~ 70%

EuropeEurope

Persistence

The strength of 70%The strength of 70%The strength of 70%The strength of 70%

Eradication

~ 70%

Europe

Persistence

Eradication Eradication

~ 70%

EuropeEurope

Persistence

• Field planning

Per capita number of baits to get >70%

• Quality Assessment

Control programs with sero <70% failed

• Modelling

Concordance in predicting 70% validates

Revising the Revising the

benchmarkbenchmark

Revising the Revising the

benchmarkbenchmark

EcoEpi – Helmholtz Centre for Environmental Research UFZ

Simulation Model

Eradication

~ 60%

~ 70%

Conservative Improved

Europe

Persistence

Anderson’s model + individual foxes + local transmission = …

IndividualsPopulation

ReasoningReasoningReasoningReasoning

Flying FoxesFlying Foxes Biological Foxes Biological FoxesRevised BenchmarkRevised Benchmark

EcoEpi – Helmholtz Centre for Environmental Research UFZ

Fox density in spring no rabies [per km²]

Pre

dict

ed

Her

d Im

mun

ity

Reference

Flying Foxes

Revising the benchmark

Biological Foxes

Quantifying benefitQuantifying benefitQuantifying benefitQuantifying benefit

Quantifying possible benefit… Quantifying possible benefit… Quantifying possible benefit… Quantifying possible benefit…

0

5

10

15

20

25

30

0% 20% 40% 60% 80% 100%

Desired population immunization

Ba

its

pe

r k

m2

Today’s target 75%

10%less

Apply relation to field strategy…

20

14

20 instead of 14 baits/km2

cost additionally

120.000 € p.a.

per 10.000 km² vaccination area

Construct relation between bait density and

immunization level…

Simulation:Target immunity down by

10 percentage points necessary baits decrease by

one third.

SummarySummarySummarySummary

Summary Summary Summary Summary

Appropriate modelling and field

observations coincidentally suggest 60%

herd immunity and as useful target in

rabies controlthus

Relative to today's baiting strategy one

third of applied resources could be saved

by applying 14 baits per sq km

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1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002

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inve

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1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002

case

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??

Thank you for your attention Thank you for your attention Thank you for your attention Thank you for your attention

D. Eisinger

L. Tischendorf

M. Müller

V. Grimm

F. Jeltsch

C. Wissel

T. Müller

C. Staubach

T. Selhorst

H. Schlüter

EcoEpi – Helmholtz Centre for Environmental Research UFZ

Simulation Model

Target down by 10 percentage points

=

Baits decrease by 30%

General relation:General relation:

EcoEpi – Helmholtz Centre for Environmental Research UFZ

0

1

2

3

4

0 10 20 30 40

Time [years]

Po

pu

lati

on

de

ns

ity

N(t

)A

nd

ers

on

et

al.

(1

98

1)

0

200000

400000

600000

800000

Hu

nti

ng

ba

g (

Ge

rma

ny

)

K=3, Kt=1

0

1

2

3

4

0 10 20 30 40

Time [years]P

op

ula

tion

den

sity

(E

isin

ger

& T

hu

lke)

0

200000

400000

600000

800000

Hu

ntin

g b

ag (G

erm

any)

Population model

(Anderson et al. 1981)Individual-based model (Eisinger et al. 2005)

Two models of fox rabies

Start of vaccination campaign

Start of vaccination campaign

Both models reflect dynamics of field data correctly!

EcoEpi – Helmholtz Centre for Environmental Research UFZ

Vaccination

Biannual bait distribution along flight lines

Individual bait consumption

Transmission

Within group contacts

Neighbourhood contacts

Mating activity

Dispersal

Foxes in families

Mortality/Reproduction

Dispersal

Simulation Model