The Role of CEA (Center of Animal Encephalopathies) in the BSE Surveillance: BSE in Italy

Abstract

Bovine spongiform encephalopathy (BSE) is a neurodegenerative disease that affects cattle, associated with the detection of a protease-resistant protein called PrPsc. BSE was detected first in the UK (Wells et al., 1987) and then described in many European countries, including Italy (Guarda et al., 1994). Exposure to the agent of BSE is the most probable cause of a new disease in man, variant Creutzfeldt–Jakob disease (Bruce et al., 1997; Hill et al., 1997). The evidence prompted public concern about the human risk in consumption of bovine-derived products and led to enhanced surveillance of BSE, which was in the early years based on the passive approach. This kind of surveillance identified the only two BSE cases in Italy up to 2001. The introduction in Italy of a system of active surveillance for BSE using the new rapid test in January 2001 has provided the opportunity to ascertain the presence of BSE in indigenous Italian cows. Between January and 5 September, 230 670 samples were examined by the national network of the Istituti Zooprofilattici and 26 positive BSE cases were detected, with a prevalence of 1.13 per 10 000 animals tested. Nine of these belonged to risk categories (3 fallen stock and 6 emergency slaughter) and 17 were regularly slaughtered cattle. The prevalence is 1.3 per animal tested. All the cases except two were born after the 1994 feed ban. The mean age at diagnosis was 6 years (range 4–13 years). The neuropathology of all 21 Italian BSE cases is chacterized by the same patterns of spongiosis (degree and distribution) and PrP immunopositivity as those reported in other European countries (Wells et al., 1992; Orge et al., 2001; Tegtmeier et al., 2001), although the histology, immunohistochemistry (IHC) and Western blot (WB) findings were limited to the same sample taken for the rapid test (a section of pons at the cerebellar peduncles and obex level). Conspicuous spongiosis in the neuropil of the grey matter and neuronal perikarya vacuolation were observed in all cases except for one that showed minimal spongiform changes. In all the other cases, severe vacuolar changes occurred in the neuropil, mainly in the solitary tract nucleus and in nucleus of the spinal tract of V; mild spongiosis was observed in the dorsal nucleus of the vagus nerve. Vacuolization of neuronal perikarya was predominantly observed in the vestibular nuclear complex, in the reticular formation and, to a lesser extent, in the dorsal nucleus of the vagus. Mild astrocytosis was visualized in each sample by