Researchers at the Imperial College, London, had been some of the last holdouts arguing that the mad cow disease epidemic could result in hundreds of thousands of deaths. When researchers at Saint-Antoine Hospital published a study in late 2001 suggesting that at most a few hundred people would die from VCJD, for example, the Imperial College researchers said that claim was far too low because it ignored initial underreporting of VCJD cases.
But Azra Ghani, Christl Donnelly, Neil Ferguson and Roy Anderson published a study this week that affirmed the findings of studies that projected more conservative results. The Imperial College researchers now project that over the next ten years only 50 to 540 people in Great Britain are likely to develop VCJD from having eaten tainted beef. In addition, most of those cases will occur in the next few years rather than being spread out over the next decade.
Essentially, the researchers looked at their model that had been projecting 50,000 or more cases and then looked at the actual data over the past few years which simply didn’t fit that prediction. Ghani, et al., note that there is now enough evidence to predict with more confidence the incubation period of VCJD which they estimate to have a mean of 12.6 years (which happens to be very close to the estimated 10-13 years that kuru takes to incubate).
Sources:
Updated projections of future vCJD deaths in the UK. Azra Ghani, Christl Donnelly, Neil Ferguson and Roy Anderson, BMC Infectious Diseases, 2003, 3:4.
Scientists cut predictions of human mad cow cases. Patricia Reaney, Reuters, May 20, 2003.