Bovine spongiform encephalopathy: observations on the incidence during 1992
Wilesmith, J.W.; Ryan, J.B.
Veterinary Record 132(12): 300-301
1993
ISSN/ISBN: 0042-4900 PMID: 8470346 Document Number: 417082
The age-specific incidences of bovine spongiform encephalopathy (BSE) in herds in which cases occurred in 1989, 1990, 1991 and January to June 1992 are presented. Analyses were restricted to those herds in which all cases were homebred animals, where the exact date of birth was available for every case and for which the age distribution of the adult herd was known. Information was obtained by means of a standard questionnaire. The incidence within the 2-year-old age class was 0.027% in 1991 compared with 0.07% in 1989 and 1990. The reduced incidence in the 2-year-old class observed in January to June 1991 (0.01%) was sustained in the first 6 months of 1992 (0.01%) and the incidence within the 3-year-old class was lower in the first 6 months of 1992 (0.46%) than the first 6 months of 1991 (1.52%) and of 1990 (0.84%). As expected the incidence in animals of 4 years of age and older increased in successive years. It is concluded that these analyses indicate that preventing the exposure of cattle to infected meat and bone-meal has had the effect expected.