Issue |
Vet. Res.
Volume 34, Number 3, May-June 2003
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Page(s) | 261 - 272 | |
DOI | https://doi.org/10.1051/vetres:2003002 | |
How to cite this article | Vet. Res. (2003) 261-272 |
DOI: 10.1051/vetres:2003002
Temporal and spatial patterns of the clinical surveillance of BSE in France, analysed from January 1991 to May 2002 through a vigilance index
Marie Cuenota, Didier Calavasb, David Abriala, Patrick Gasquia, Géraldine Cazeaub and Christian Ducrotaa Unité d'Épidémiologie Animale, INRA Theix, 63122 Saint-Genès-Champanelle, France
b Unité Épidémiologie, AFSSA Lyon, 31 av. T. Garnier, 69364 Lyon Cedex 07, France
(Received 2 August 2002; accepted 25 November 2002)
Abstract
Between 1991 and mid 2000, the surveillance of Bovine Spongiform Encephalopathy
(BSE) in France was based solely on clinical surveillance through a Mandatory
Reporting System. Since 2000, the implementation of active surveillance programmes
using rapid tests, as a complementary tool targeted at dead and slaughtered cattle
has shown that part of the BSE cases were not detected with the clinical surveillance.
In order to obtain a better knowledge of the strength of the clinical surveillance,
we analysed a vigilance index defined as the ratio of negative clinical suspicions to the
cattle population in the region and period of interest. The temporal analysis of the
vigilance index showed that it did not vary much between 1991 and 1999, increased sharply
since 2000, and then decreased partly in 2001. The geographical analysis of the variations
of the vigilance index was performed at the department level by comparing the observed
number of negative clinical suspicions per department to the expected number, computed on
the basis of the national average index and standardised on the production type of
the cattle - dairy versus beef suckling cattle. As assumed, the data followed a Poisson
distribution. We observed a high geographical variation of the vigilance index:
ten departments out of 91 presented a significantly higher vigilance index than the
national one, and four a significantly lower vigilance index. The vigilance index showed
that the clinical surveillance was heterogeneous during the past twelve years, both in
time and geographic location, in a range of one to ten. So the apparent trend in the BSE
epidemic during this period as well as the differences in the spatial incidence of
BSE have to be analysed with caution.
Key words: BSE / epidemiology / surveillance / vigilance / cattle
Correspondence and reprints: Christian Ducrot Tel: (33) 4 73 62 42 63; fax (33) 4 73 62 45 48;
e-mail: ducrot@clermont.inra.fr
© INRA, EDP Sciences 2003