Subject: Re: Maternal transmission of BSE in cattle

From: [email-masked] (J Ralph Blanchfield)
Date: Fri, 02 Aug 1996 10:01:25 GMT

Hello Everyone,

Further to my post on 1 August, in which I wrote

>If a low level of maternal transmission occurs, it has, of course,
>been occurring during the dramatic year-on-year decline of the numbers
>of new cases in recent years, and likewise has no bearing on the
>further decline forecast over the next few years. It may well,
>however, prevent virtually complete eradication of BSE. 

Now that some more information is available, it seems that in the
long-term field trial,  all of the BSE cases in offspring from
BSE-infected dams occurred among those born in the last six months of
the dams incubation period, and that this suggests that in a normal
herd, the level of transmission would be of the order of 1 per cent.

In that case the chance of an infected calf would be one in 10,000 in
the third generation. 

This would not "prevent the virtually complete eradication of the
disease", as I previously suggested; at most it would marginally
prolong the "tail of the curve" as it approaches zero.

Regards

Ralph

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J Ralph Blanchfield
Food Science, Food Technology & Food Law Consultant
Chair, IFST Member Relations & Services Committee
Web Editor, Institute of Food Science & Technology
IFST Web address: http://www.easynet.co.uk/ifst/ 
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