Any epidemic of variant CJD, the human form of the cattle brain disease BSE, may be much smaller than previously feared, according to new evidence, writes Natasha Gilbert.
In a study published in the online journal BMC Infectious Diseases , researchers from the department of primary care and population health sciences at Imperial College London say they are much more certain about the future course of the disease and predict between 40 and 100 future deaths in total.
Azra Ghani, one of the study's authors, told The THES : "Our results show a substantial decrease in the uncertainty of the future size of the primary epidemic (from cattle to humans)."
The researchers' predictions are based on the number of vCJD deaths in the UK occurring up to the end of December 2002.
Latest figures show a recent decrease in deaths due to the disease: 17 cases in 2002, compared with 20 in 2001 and 28 in 2000. Since CJD's emergence in 1995, there have been 129 reported cases, of which seven people remain alive.
The study states: "The primary vCJD epidemic in the known susceptible genotype in the UK appears to be in decline."
According to Dr Ghani, the significant drop in the number of vCJD cases over the past two years means that a large epidemic of the incurable disease is improbable.
She said: "We now feel that the very large epidemics (thousands to tens of thousands) are extremely unlikely." But the findings give no indication of the potential threat of transmission from human to human via blood products or surgical instruments.
"While we haven't yet identified anyone infected in this way, the theoretical possibility of secondary transmission remains," Dr Ghani said.
"Given these uncertainties, it is difficult at the current time to say whether this could be a problem or not in the future."