|Cook, A. R. - UNIVERSITY OF CAMBRIDGE|
|Gibson, G. J. - UNIVERSITY OF EDINBURGH|
|Gilligan, C. A. - UNIVERSITY OF CAMBRIDGE|
Submitted to: Internet Web Page
Publication Type: Review Article
Publication Acceptance Date: January 23, 2008
Publication Date: February 26, 2008
Citation: Cook, A., Gibson, G., Gottwald, T.R., Gilligan, C. 2008. Constructing the effect of alternative intervention strategies on historic epidemics. Journal of the Royal Society Interface, 5:1203-1213. doi:10.1098/rsif.2008.0030 Interpretive Summary: Citrus canker continues to be an important disease in Florida and currently threatens other citrus producing states. During the eradication campaign in Florida, epidemiological estimations were made that drove the eradication program. In retrospect, the entire historical epidemic was review and modeled using a retrospective approach to determine the best eradication method that could have been applied. Although this approach could not have been helpful for the prior eradication program because all of the information necessary to general such a model did not exist until after it was over, it nevertheless is of considerable value to determine the besti possible approach should this disease be introduced into oter citrus growing areas/states. In addition to citrus canker, an epidemic of the common cold virus was also retrospectively applied. The methods used are an extension of existing epidemiological theory and knowledge and could be applied to other epidemics as well.
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 twoexamples. First, using temporal data for the common human cold, we show the improvementunder 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 ffectiveness 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.