01935nas a2200205   4500008004100000245013700041210006900178300001400247490000800261520121700269653003501486653002201521100002801543700002501571700001801596700001901614700002001633700002901653856004701682       2010                        eng d00aA statistical model to detect asymptomatic infectious individuals with an application in the Phytophthora alni-Induced alder decline0 astatistical model to detect asymptomatic infectious individuals   a1262-12690 v1003 a<p>In some diseases—in particular, tree root infection—stages of infection and inoculum production level and timing are not readily observable because of uncertainty or time lags in symptom appearance. Here, we pose a criterion, based on relative hazard of disease symptoms, to discriminate between healthy and asymptomatic infected individuals. We design a statistical procedure to estimate the criterion for a 6-year survey of alder decline along a northeastern French river. Individual tree symptom hazard was modeled with Cox’s regression model, taking estimation of local infection pressure as a risk factor. From an inoculum production experiment, we thereafter assessed the inoculum production level of target trees, including symptomatic and asymptomatic trees ranked according to their symptoms hazard. Using receiver operating characteristic methods, we first evaluated the criterion performance and determined the discrimination threshold to sort out asymptomatic individuals into healthy and infected. Then, we highlighted the fact that the infected asymptomatic trees were among the major inoculum producers whereas severely declining and dead trees were found to be poor inoculum sources.</p>10aspatial point pattern analysis10asurvival analysis1 aElegbede, Chabi Fabrice1 aPierrat, Jean-Claude1 aAguayo, Jaime1 aHusson, Claude1 aHalkett, Fabien1 ac}ais, Beno{\^ıt Mar{\c  uhttp://dx.doi.org/10.1094/PHYTO-05-10-0140