Farmers Guardian Jan 17 2003 page 18

BSE transmission in sheep unlikely

The transmission of BSE to scrapie resistant sheep by injecting the BSE prion directly into the brains of sheep has no bearing on the possible transmission of BSE to sheep through feeding meat and bone meal, said Moredun virologist, Dr Hugh Reid

He said that, while there was a theoretical possibility that sheep were exposed to BSE and did become infected, all the evidence made it extremely unlikely that sheep represented a possible source of infection to man at the present time.

Moredun workers did not believe there was BSE in the British sheep flock for a number of reasons.

Firstly, a ban on the inclusion of all meat and bone meal in ruminant feed was introduced by the Government in July 1988, being extended in September 1990 to include a ban on inclusion of MBM in all livestock feed. A further ban on all animal protein in livestock feeds followed in March 1996.

In any case, the total incorporation of MBM in sheep rations was only ever 2 per cent of that used in cattle feed.

Also lactating ewes and lambs were generally fed only limited amounts of concentrate. Only pedigree rams would have been intensively fed and generally this was a high-energy diet.

Commercial sheep were seldom kept for more than six years so very few animals born before 1994 were still alive. For BSE to be present in the sheep flock, vertical transmission would have to occur. There was evidence that BSE occurred vertically in cattle but only rarely.

Most lamb was under one year of age when eaten - an age when infectivity of BSE was least likely to be found.

Looking at data, figures from the Veterinary Laboratories Agency published in August 2000 showed no evidence of increased incidence of scrapie during the BSE epidemic. Also in 2000, the Veterinary Record reported a survey that showed scrapie in home-bred animals was twice as likely in hill flocks as in lowland flocks.

In other words, those animals with potentially the greatest exposure to MBM were the least likely to be affected by scrapie.

Also, surveillance studies published in the SEAC report showed a much greater incidence of BSE in cattle in some UK counties than others, yet the Veterinary Record survey showed no evidence of increased clinical scrapie in these same regions.

Finally, detailed analysis of material from 180 suspected cases of scrapie were shown to be scrapie and not BSE.