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United States Department of Agriculture

Agricultural Research Service

Title: Constructing the effect of alternative intervention strategies on historic epidemics

item Cook, A. R.
item Gibson, G. J.
item Gottwald, Timothy
item Gilligan, C. A.

Submitted to: Proceedings of the Royal Society of London B
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/1/2008
Publication Date: 7/1/2008
Citation: Cook, A., Gibson, G., Gottwald, T.R., Gilligan, C. 2008. Constructing the effect of alternative intervention strategies on historic epidemics. Proceedings of the Royal Society of London B. doi:10.1098/rsif.2008.0030

Interpretive Summary: Historical citrus canker data from the Florida citrus canker eradication campaign and data collected to develop effective eradication measure for citrus canker during the 10-yr period of 1996-2006 were reexamined in totality as a model data set to develop improved eradication models and test their validity. The purpose was not to critique the Florida eradication program that sufficiently held off the epidemic for 10 years, but to retrospectively see if there could be improvements in eradication strategies that could help if canker were to occur in other US citrus industries or cir\trus industries in other countries. New models were developped to more precisely predict citrus canker increase, spread, and to test intervention strategies, and shown to be useful predictors of the historical epidemic. Method of how to use this model to devise maximized eradication strategies with minimal impact to homeowner and commercial trees are described.

Technical Abstract: Data from historical epidemics provide a vital and sometimes under-used resource from which to devise strategies for future control of disease. Previous methods for retrospective analysis of epidemics, in which alternative interventions are compared, do not make full use of the information; by using only partial information on the historical trajectory, augmentation of control may lead to predictions of a paradoxical increase in disease. Here we introduce a novel statistical approach that takes full account of the available information in constructing the effect of alternative intervention strategies in historic epidemics. The key to the method lies in identifying a suitable mapping between the historic and notional outbreaks, under alternative control strategies. We do this by using the Sellke construction as a latent process linking epidemics. We illustrate the application of the method with two examples. First, using temporal data for the common human cold, we show the improvement under the new method in the precision of predictions for different control strategies. Second, we show the generality of the method for retrospective analysis of epidemics by applying it to a spatially extended arboreal epidemic in which we demonstrate the relative effectiveness of host culling strategies that differ in frequency and spatial extent. Some of the inferential and philosophical issues that arise are discussed along with the scope of potential application of the new method.

Last Modified: 10/19/2017
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