29 March 1996

Cases fall 27% on 95

THE number of BSE cases fell sharply again this year with a total of 761 confirmed BSE cases from Jan to mid-March, 27.5% down on the same period last year. That puts total cumulative figures to Mar 15 96 at 158,882. Current average weekly incidence is 250 cases compared with 917 cases a week at peak incidence in Jan 93.

Figures for 1995 showed a drop of 40% compared with 1994 at (January-December) 23,943 confirmed cases compared with just 12,255 in 1995 (Jan-Dec).

In 1995 there were 1383 cases in animals born after the introduction of the ruminant feed ban in July 1988. Of these only one case was under two years old; 90 cases were three years or under. Up to Oct 31, 1995, 23,148 BSE cases confirmed in animals born after feed ban.

Reduced incidence in animals five-years-old and under has been maintained (see Fig 1). This is also now demonstrated in six-year-old animals, in which age group the incidence of the disease has fallen from 6.21% of the number of animals at risk in herds with home-bred cases with a clinical onset in 1994, to 3.43% in 1995.

Within-herd incidence in affected herds (always low at below 3%) and an indicator of possible horizontal spread, declined from a peak of 2.72% in 1992 to 2.06% in 1995. This supports the view, along with other evidence, that horizontal spread is not a significant factor in maintaining the disease.

National annual incidence also peaked in 1992 at 0.92% of all adult cattle, falling to 0.33% in 1995.