Tree-based Classifiers and GIS for Biological Risk Forecasting

A tree-based classifier of tick presence, developed to estimate the risk of tick-borne diseases, is currently being interfaced and applied with a Geographical Information System (GIS) based on GRASS (USA-CERL Geographic Resources Analysis Support System). Environmental factors (altitude, substratum, vegetation, exposition, etc.) and tick sampling are used to predict occurrence of the parasite Ixodes ricinus on a target territory. A Tcl/Tk interface to GRASS has been developed for regional data from the Sistema Informativo Ambiente Territorio (S.I.A.T.) of the Autonomous Province of Trento. The system predictions are consistent with the current knowledge of tick ecology and can be used for an effective control of tick-borne diseases

Ixodes Ricinus (Acari: Ixodidae) Infestation on Roe Deer (Capreolus Capreolus) in Trentino, Italian Alps

The most important tick-deer system potentially supporting the epidemiology of Lyme disease in the Italian Alps is that regarding Ixodes ricinus (L.) and roe deer (Capreolus capreolus L.). In this study, the pattern of tick infestation on 562 male roe deer harvested in Semptember 1994 in 56 game districts of Trentino, Nothern Italy, was assessed. The prevalence and density of infesttiion by I. ricinus were analyzed by a model based on classification and regression trees (CART), using both discrete and continuous variables concerning environmental and host parameters. The model discriminated altitude and host density as the 2 variables having the greatest effect on the prevalence and density of infestation in deer; the levels of infestation were higher at an altitude below 1125 m or at roe deer densietes over 8.5 head per 100 ha. The density of tick infestation tended to be higher in older roe dee

A New Bootstrap Method for Risk Assessment ofExposure to Lyme Disease

Lyme borreliosis, now the most common vector-borne illness in North America, may involve cardiac manifestations as atrioventricular block, myopericarditis, and rhythm disturbances. The overall prognosis of Lyme carditis is good, but temporary cardiac pacing may be required and late dilated cardiomyopathy may occur. Borreliosis should be suspected in all patients with unexplained cardiac symptoms (supraventricular tachiarrhythmia and especially in atrioventricular block of unknown origin in young patients) who have been exposed in regions invaded by the epidemic. Risk assessment of exposure to bites of infected ticks is thus needed for prevention and accurate diagnosis of borreliosi

An Application of the Bootstrap 632+ Rule to Ecological Data

We applied the novel bootstrap 632 rule to choose tree-based classifiers trained for modeling the risk of parasite presence in a host population of ungulates. The method is designed to control overfitting: compact classification trees (CART) are selected using a nonlinear combination of the resubstitution error and the standard bootstrap error estimate. Model selection based on the 632 rule offers a gain over cross-validation for CART models. The tree classifier selected by the new rule for this application favourably compared with standard multivariate GLIM models