NR AWHI
AU Ingravalle,F.; Crescio,M.I.; Caramelli,M.; Ru,G.
TI Estimation of past and future BSE cases in Italy
QU International Conference - Prion 2006: Strategies, advances and trends towards protection of society - 3.10.-6.10.2006, Torino, Italy, Lingotto Conference Centre - Poster sessions EPI-10
PT Konferenz-Poster
AB BSE in Italy was firstly detected in 2001, and during the period 2001-2005, 125 autochtonous cases were identified by active surveillance and 1 by passive surveillance. During the first two years of surveillance the reported cases were 89, then the infection decreased up to 8 cases in 2005. Detailed epidemiological models, from the classical mathematical modelling route, were developed and applied to BSE in several European countries. A simplified model was developed in 2004 and applied to the Italian BSE epidemic. First data (updated to 31/12/2004) showed that the main infection occurred in 1993-2000 (the peak in 1996) and 235 cases were expected before 2001, 556 in 2001-2003, 171 after 2003. Our purpose is to update the data to 31/12/2005 and compare the new results with the old ones. The model is a backward calculation based on some demographic features of the observed cases (as date of birth or age at BSE detection), of the population (as survival function, age distribution) and of disease (as incubation period). First step of the model is the estimate of the age of cases at infection, obtained by combining the distribution of incubation period with the age at detection of BSE. Demographic data about population allow us to know the size of the cohorts of each case. Assuming that all the animals belonging to the same cohort shared the same risk of the cases detected in that cohort, we estimate the distribution of the age at infection for the cohorts, combining the size of the cohorts with the age at infection of cases. Re-introducing the survival function and the incubation period in this last estimation we obtain an estimate of the number of infected animals that reached alive at a certain age in a certain year. The application of this model to data updated to 31/12/2005 shows results not dissimilar from those previously reported.
AD CEA- National Reference Centre for TSEs, Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d'Aosta, Turin, Italy; E-mail: francesco.ingravalle@izsto.it
SP englisch
PO Italien