Letter: Beef: `meat products' may be infected, but only a few people wi ll ever get CJD

Sir: Here are the answers to the questions about BSE/CJD which you posed on the front page on Saturday 23 March.

1. One bite of infective (brain) material might be enough to transmit the disease because it is dose-related but that is unlikely. In any case, most individuals will never develop CJD since only those of a rare genotype are susceptible.

2. Recent research on BSE suggests that beef liver is unsafe.

3. There is no evidence that the "red meat" of BSE-infected animals is any less wholesome than that of Scrapie-infected sheep, whose meat we have been swallowing with impunity since 1730. It is the "meat products" (pates, meat pies, stock cubes and tinned items of "beef" such as consomme and stew) to which brains have been - and calves' brains still are - added which contain the organism.

4. Farmers no doubt watch their pigs but all subclinically infected animals appear quite healthy for years.

5. All poultry appear to be immune. The SEAC researchers are playing safe in barring all mammalian meat from all farm animals.

6. This is not going to be what everybody understands by an "epidemic": we are not dealing with typhoid or tuberculosis or cholera in which everybody undiscriminately gets contaminated. This unique organism causes disease in only a few individuals - those who are genetically susceptible. That's why CJD, in spite of being an infection, is so rare.

H C Grant, MD, FRCP

(Neuropathologist)

Edinburgh