The 30 AFSSA experts believe the guarantee criteria in the UK's date-based export scheme (DBES) "are not a criteria for exclusion and point out that "more than half of all UK herds have had at least one case of BSE". The experts say the BSE incubation period for cattle is unknown (in the absence of a sufficiently sensitive test), for the UK measures (elimination of tissue and organs likely to carry the BSE prion) to be considered completely effective on the face of it. Particularly as these guarantees are based on "the premise that measures taken for managing and banning meat and bone meal and cow-to-calf transmission are enough to exclude any risk of BSE", say the French scientists. The existence of other channels of contamination, other than the main one (food) and the vertical cow-to-calf one (maternal transmission) has not been ruled out. The experts say that the slowdown of the rate of decline in the number of cases of BSE in the UK, in spite of the steps taken, should prompt officials to start asking questions about the way in which the BSE agent is being transmitted.Latest scientific findings.According to provisional figures on prevalence (i.e. the number of cases recorded in a given cattle herd, as at July 31, 1999), nearly 3,000 cases could be recorded in 1999. In view of the size of the British cattle population, this would mean something like 650 cases per million cows aged over two. This compares, in the same conditions, with the French prevalence of between 1.5 and 2 and that in Northern Ireland of between 10 and 15. Figures on cattle counts on farms where BSE has been diagnosed show no cases born after December 1995. Animals aged under 44 months are either not infected or have not had the time to develop symptoms given the average age at which they appear (54-60 months). "Given the present state of information, neither of the two theories can be confirmed or rejected. What is more, contamination prior to August 1, 1996 and more importantly, the more recent ones, are not likely to be identified, in the form of clinical cases, before 2000-2001". Recently validated by the Commission, BSE detection tests being developed should be able, in a few months' time, to produce key information about the number of cows contaminated in groups born in 1996 and 1997.The reliability of the programme set up, which is based on identifying and tracing animals (designed to control any risk of error or fraud concerning the eligible status of...

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