Richard Rhodes, Deadly Feasts: Tracking the Secrets of a Terrifying New Plague (Simon & Schuster, New York, 1997). 259 pp. ISBN 0-684-82360-8.
Of all the strange and terrifying organisms that afflict humankind, few can match the ones now considered to be the cause of prion diseases -- which the author characterizes as "ineradicable, untreatable, irreversibly fatal diseases." This is a scary book, not for the queasy or the faint of heart, but reading it provides an excellent overview of the decipherment of some of the greatest medical mysteries of our century. The diseases discussed, Kuru, Creutzfeldt-Jakob (CJD), scrapie, and mad cow disease appear to be caused by something which -- it was long argued -- could not exist, an infectious organism devoid of DNA.
The book begins with a long and detailed history of the forty years of work carried out by Carleton Gajdusek among the Fore of New Guinea. These people suffered for centuries from a mysterious neurological disease, invariably fatal, named Kuru. Gajdusek was able to establish that this disease derived from the cannibalistic practices of the Fore -- who were accustomed to eating their dead. Once the cannibalism stopped, Kuru disappeared. This statement is, of course, a vast oversimplification. Numerous other scientists worked on aspects of the problem, and the work of all of these is detailed in the book. But it is Gajdusek who received, and deserved, major credit, attested by his being awarded the Nobel Prize for these investigations.
The book then continues with a short history of the Creutzfeld-Jakob disease -- obviously closely correlated to Kuru because of the similarity of the brain lesions in both. Another disease in this family is one well-known for centuries -- a disease of sheep called scrapie. The infective agent turned out to be virtually indestructible. It survived 30 minutes of boiling and two months of freezing, also disinfection with strong formaldehyde, carbolic acid, and chloroform. Whatever it was, it passed through fine filters and was small enough to stay in solution in a centrifuge at 400,000 revolutions per minute. It remained viable in dried grain for at least two years. And it was transmissible!
There was no doubt about the infectivity of these agents. They could produce the diseases studied in a variety of laboratory animals. But, try as they might, researchers were unable to isolate an infective agent, virus or microbe, containing DNA. It slowly dawned on some researchers that perhaps this infective agent was a protein, not a virus. But this was against all the rules -- an infective agent that reproduced without nucleic acid would be unique! But how else to explain the fact that when researchers challenged suspensions of scrapie with enzymes known to damage nucleic acids (DNA) there was no reduction in their infectivity, but when scrapie was challenged with enzymes kown to damage proteins, infectivity was reduced by more than 90%?
Perhaps the saddest part of this (to me) disturbing book was the occurrence of CJ disease in youths who had been injected with growth hormone derived from pituitary glands harvested from cadavers. A number of such cases and deaths occurred before physicians could be alerted to the dangers. The total death toll has reached 80 worldwide. It soon became evident that any human tissue used in therapeutic transfer carried an unavoidable risk of transmitting the infection. Gajdusek and Gibbs, a colleague, prepared a technical note for the Journal of Neurosurgery warning of the dangers.
The last part of the book deals with happenings familiar to all of us who have read of the "mad cow disease" in Britain, the banning of British meat and cattle by the European community and the enormous financial loss and -- to put it bluntly -- black eye to the British reputation that these happenings entailed. The problem started in April 1985 when cattle in Britain began to die of what was designated BSE ("bovine spongiform encephalopathy"). It acquired its nickname, "mad cow disease," because of the nervous agressive behavior it provoked in normally peaceful animals. It was puzzling at first to understand why and how cows, which had pastured next to sheep for centuries, had never acquired the disease, yet were now infected. It was proved that the cattle were now being fed meat and bone meal which included the remains of infected sheep. The toll among British cattle steadily mounted and in 1993 the inevitable happened. Two farmers died of CJD. Then a young girl of fifteen sickened. When a biopsy of her brain showed the dread disease, an investigator from the government CJD surveillance unit in Edinburgh visited the girl's grandmother and warned her to keep quiet about her granddaughter's illness. "Think about the economy," he told her. "Think about the Common Market!" The girl was in a coma for a year before her death. By the beginning of 1996, ten young people in Britain had died of the disease heretofore known only in the middle aged and elderly.
In March 1996 the Secretary of State for Health of Great Britain "informed a stunned nation that BSE had probably spread to humans eating beef." This announcement produced worldwide scare headlines and continues to frighten people in both Europe and the United Kingdom, since there have been legal and illegal exports to Europe of British cattle and meat products.
There are wryly amusing sidelights to the story. To restore consumer faith in Swiss beef the Swiss government announced it would destroy 230,000 cattle born before it outlawed meat-and-bone meal. However, it also announced that the remains would be processed into meat-and-bone meal and fed to pigs! The pork would be exported!
Among other topics, the last chapter deals with some worst-possible-case scenarios. There may be a peak human epidemic in Britain occurring in 25 years -- around 2015 -- resulting in 200,000 deaths per year among people who ate infected meat now. The parting shot in the book is a discussion of xenotransplantation -- grafting animal organs and tissues into humans. The problems inherent in such a process are well discussed. There are enormous advantages -- and equally important perils.
By the way, if you use bone meal on your roses, be sure to wear gloves and a dust-excluding mask when applying it.
- Irma S. Jarcho
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