Mad cow chronicles

There is a substantial range of historical observations on scrapie in sheep. This suggests overall that there may have been two rather distinct sets of symptoms. In Britain our "scrapie", "staggers" or "goggles" was largely of the kind associated with itchiness leading to violent rubbing with loss of wool, aimless wanderings, stumbling and becoming progressively weaker and dying, often of starvation and dehydration. This old scrapie has been around in British flocks since the 18th century and it was probably introduced with Spanish fine wool sheep. The second type is associated with apparent vertigo, arched backs, stiffness and trembling leading to severe convulsions until the animals can no longer stand and are often killed in mercy. This maladie folle or tremblante of France may possibly have increased in British sheep, though only more recently.

Harash Narang suggests that BSE probably did not originate from the old scrapie but may have arisen from the newer tremblante type. That is a significant inversion of suggestions elsewhere that if there is a new type of scrapie in sheep then it must have arisen from BSE cattle. Perhaps the new diseases of both cattle and humans have come from a common source. His two books were written before it became clear that BSE and human new-variant CJD are connected with each other but neither of them closely with old scrapie.

Historical accounts from shepherds suggest that old scrapie was venereally passed from male sheep and became epidemic by the practice of tup (stud male sheep) letting. Whether or not the ewes served became diseased themselves, their lambs had a high chance of developing scrapie. This possible transmission by semen need not imply "a dominant genetic" effect but infected seminal plasma. If the shepherds of old were correct, it would be worth paying more attention to semen for monitoring infectivity. Attention, however, has been given to maternal not paternal transmission. Narang records that in 1962 large numbers of tissues and fluids from goats were examined as possible sources of infectivity, but semen was not included. How very odd, when one considers the possible consequences for the spread of infection. Both sheep and goats tend to eat their shed placentae, so there is also need to consider that maternal route as well, but no need to invoke maternal genes.

Narang's substantial work, begun in late 1960s, has been in electron microscopy. In this he has been involved with others, notably Efraim Field and subsequently Carlton Gadjusek, in identifying two different structures, both clearly related to all the spongy encepahalopathy diseases. These are, first, three-layered tubules that are quite extraordinarily similar to those in measles, and, second, thinner structures that seem to be the inner core of the three-layered tubes - the "scrapie-associated fibrils" of other observers. It appears that between the inner core and the outer layer of the tubule may occur a coiled single-strand nucleic acid that is easily mislaid, but this does not yet convince die-hard prionologists. The protection afforded by single-strandedness and by this unusual structure can well account for its resistance to destruction.

More recently Narang, having recognised before others the crucial importance of developing a diagnostic test of infectedness before the outbreak of disease rather than post mortem, has clearly been at the forefront of that endeavour. Details of his tests have been published in the scientific literature as well as in the first of these books. Their application would imply acceptance of the possibility of infectivity well before development of the macro-pathologically identifiable diseases. That very reasonable view has been, to say the least, a political hot potato. In the face of opposition from some of "the establishment" and downright hostility from a guest writer in a broadsheet newspaper in August 1996, Narang decided to bring together accounts of all his and others' relevant work, together with all his historical gleanings, in one book.

The Link , privately published (as is Death on the Menu , Narang's second book), is the rather unfortunate result. It is overcrowded, sometimes repetitive, scarcely edited or proof-read and badly bound. It recalls an overgrown and muddy river that nevertheless has gems lurking in its stream bed.

An optimistic message, at least for some, is that there is reasonable ground for supposing that long-term consumption of scrapie-infected sheep may provide long-term or permanent protection from subsequent infection by the new tremblante type. This could have very important implications for exploring protection by vaccination.

Death on the Menu is absolutely appalling and for that reason should be read. It records candidly, and often more or less verbatim, not only the symptoms of CJD in the victims but the experiences, frustrations, miseries, fears and anger of those near and dear to them. Not many scientists with experience and skills in investigative biochemistry and electron microscopy have also the sense of the historical value of recording actuality, however grim, nor the ability nor the desire to empathise so closely with patients and victims of the worst crises of the human condition.

Death is the bottom line of all our curricula vitae whether by way of our food or otherwise; but almost any way to go would be better than to die as chronicled here. Death on the Menu should be on the reading list of all those who need to convince others that it is better to be allowed to go before getting right through our personal menus. No old dog with distemper would be made to stay until the bitter end.

Narang is a determined seeker after truth. He is also a polymath whose first language is clearly not English. His books are odd but interesting, and, I believe, in different ways, important. By some, at least, "IHe hath been most notoriously abused."

Colin Leakey is an applied biologist, who has made a substantial submission of evidence to the BSE inquiry.