Giulio De Leo Dipartimento di Scienze Ambientali Università degli Studi di Parma - Italy.


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EEE - ICTP Trieste April 13-15 2005 " To separate or not to winnow, this is the issue ": undersired impacts of creatures evacuation to eraticate illnesses in widlife populaces (the versatile flow of CSF in wild pigs) Giulio De Leo Dipartimento di Scienze Ambientali
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EEE - ICTP Trieste April 13-15 2005 “ To separate or not to winnow, this is the issue ”: undersired impacts of creatures evacuation to eraticate maladies in widlife populaces (the versatile motion of CSF in wild pigs) Giulio De Leo Dipartimento di Scienze Ambientali Universitã  degli Studi di Parma - Italy Thanks to A.Dobson and M. Pascual and to the NCEAS WG on Seasonality and Infectious ailments

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c : chasing rate [t - 1 ] If the instance of no winnowing ( c =0): It can be demonstrated that it is conceivable to kill the sickness if: c > r [1-1/R o ] Let’s take the Classical Swine Fever (CSF) as a source of perspective malady

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Basics of Classical swine fever (CSF) or Hog Cholera An exceptionally infectious illness because of a RNA infection , Family TOGAVIRIDAE, Genus Pestivirus; It is a List An ailment in the OIE Classification of Diseases Suidae are the sole regular hosts;

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Basics of Classical swine fever (CSF) or Hog Cholera Infected creatures may shed a lot of infection for 20 - 40 days through oronasal and lacrimal discharges, pee and excrement The immediate contact in the middle of tainted and helpless creatures is the standard method for viral transmission;

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Basics of Classical swine fever (CSF) or Hog Cholera Epidemiology CSF causes high dismalness and mortality (up to 90%) amid the first pestilence wave… however low destructive strains can be separated in wild hogs in the accompanying endemic stage; Acute contaminations Chronic contaminations/endemic stages

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CSF dissemination (OEI 1995-1997)

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CSF flare-ups in wild pigs 1990-2001

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Why individuals think about CSF in EU? Wild pigs are faulted to be the store of CSF

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Country N. Swines uprooted (  â â â â  = 1 milion example) NL 10 Germany 2 Spaain 1 Belgium < 1 Italy < 1 UE Damages from CSF somewhere around 1993 and 2000 A 100 kg pig ~ €150,00

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which is less demanding to say than to do it… The EU underpins a system to kill the infection from wild pig fundamentally taking into account decreasing populace thickness through separating What to winnow? Where to separate? At the point when to winnow? How to separate?

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b R o Culling rate [y - 1 ] 1 Culling rate [y - 1 ] Drawbacks of winnowing (1/2) as reported by the Italian Wildlife National Service (INFS) It may push hosts out of their normal home range, along these lines encouraging ailment spread ~ 20% expansion of separating rate ~ 60% diminishment of populace thickness as for steady b

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Drawbacks of winnowing (2/2) It may push hosts out of their regular home range, subsequently cultivating illness spread If winnowing is engaged basically on old (low defenseless) has, it may change populace age structure for more powerless yearlings Given the presence of different strains of CSF (Biagetti et al. 2001), an adjustment in host thickness may encourage the determination of less harmful however more tireless strains, therefore making separating all the more exorbitant and insufficient Research inquiries: Is it conceivable? On the off chance that positive, under which conditions? Which are the results?

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m c m c I 2 I 1 a 1 a 2 A straightforward two-strains rivalry model S Hosts I 1 contaminated with a L ow V irulent S train ( LVS )  little a 1 Hosts I 2 tainted with a H igh V irulent S train ( HVS )  extensive a 2 b 2 b 1 b 12 very destructive strain (substantial a 2 ) low harmful strain (little a 1 ) b 12 is the super-disease coefficient

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The new mathematical statements ( LVS versus HVS ): S\' = G( S ) - b 1 I 1 S - b 2 I 2 S - c S I 1 " = b 1 I 1 S - ( a 1 + m + c ) I 1 - b 12 I 1 I 2 I 2 " = b 2 I 2 S - ( a 2 + m + c ) I 2 + b 12 I 1 I 2 Assumptions on the LVS versus HVS Disease impelled mortality (harmfulness) a 1 << a 2 Transmission rate b 1  b 2 b 12  0

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Basic epidemiological ramifications of the above suspicions Basic Reproductive rate ( LVS versus HVS ) Threshold thickness for malady annihilation K T1 < K T2  LVS can endure in an extremely inadequate populace

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Further epidemiological ramifications If there is no super-contamination ( b 12 =0) LVS dependably outcompetes HVS

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If  LVS outcompetes HVS If  LVS and HVS exist together If  HVS outcompetes LVS where If there is super-disease ( b 12 >0)

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Further epidemiological ramifications If pig populace thickness K (also b 12 ) is adequately high, then HVS can exist together with, or even outcompete LVS  culling so as to diminish populace thickness migh expand the possibility of LVS to outcompete HVS

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Epidemiology of traditional swine fever in wild hogs of Eastern Sardinia LVS HVS from a field overview by Guberti (1998) and Artois et al. (2002)

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Prevalence at the balance as an element of separating rate, when the two strains are segregated Removal rate

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Prevalence at balance as an element of collecting exertion for two contending strains

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Total Prevalence

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Number of contaminated people

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m c S m b 2 b 1 I 2 I 1 c a 1 a 2 b 12 LVS (little a 1 ) HVS (vast a 2 ) g 1 g 2 R m c The SI 2 R model (Susceptible-Infected-Recovered )

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Conclusions It is conceivable that the decrease of host thickness by winnowing may without a doubt encourage the choice of less destructive strains This thus would lessen the edge host thickness for malady annihilation If this happens, the gathering exertion needed to totally destroy the ailment will be higher than at first expected If separating exertion is not sufficiently substantial, the net impact of this strategy is to increment both commonness and the quantity of tainted hosts The reaping exertion needed for the slightest\'s destruction harmful strains may be unreasonably high (or too exorbitant)

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Further improvements Analyze pop.dynamics by utilizing a stochastic (potentially spatially unequivocal, regular) variant of the model Introduce age structure and age-depede

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