Investigations into the death of a 40-year-old woman who may have died from variant Creutzfeldt-Jakob Disease (vCJD) have revealed unusual patterns of damage in her brain and they suspect the genetic make-up was different to all other patients so far.
CJD originally arose in cattle as bovine spongiform encephalopathy (BSE), or "mad cow disease", before appearing in a new form in humans as vJCD.
vCJD is a fatal brain condition, with dozens of cases every year in the UK.
The disease which is linked to misshapen prion proteins in the brain, has varying incubation periods according to its genetic make-up; the incurable disease causes the brain to become riddled with holes as in a sponge, causing a loss of mental faculties and eventual death.
Some experts believe that for many of those infected the timer could still be ticking, and in some cases the incubation period might exceed 50 years.
The BSE crisis in cattle in the 1980s and 1990s in Britain saw the emergence of this new form of CJD where a small number of people who ate infected material from cattle at that time went on to develop vCJD, a similar and equally lethal illness, which often did not emerge until years after the infected meat was eaten.
A culling programme in the crisis in the 80's and 90's removed infected cattle from the food chain, and deaths from vCJD which were thought to have peaked in the first half of the decade, fell steadily since 2003.
The latest case does however present the possibility that the "incubation period" for some people may be longer, and that there could be a second upsurge in deaths.
To date every person who has died from vCJD has carried a gene variant called MM of which 4 in 10 people have.
Some experts suggest that in humans, only those people may ever have been vulnerable to vCJD however the latest death is the first recorded involving a different variant - VV - found in approximately 1 in 10 Britons.
According to lead researcher Dr. Simon Mead, from the Prion Unit at University College London, it is too early to say whether this indicates the start of a rise in cases among other VV carriers exposed to BSE-infected meat.
Dr. Mead says it is still unclear if the case is a new type of vCJD affecting VV people and lot more cases would be needed to confirm this.
Professor Higgins, the Chair of the government's Spongiform Encephalopathy Advisory Committee (SEAC), which advises on vCJD, says there is no need to panic as this could simply be a case of sporadic CJD, in which case the genetic makeup is irrelevant, as this is found in MM and VV people.
Since the disease was first recognised in 1995 there have been 114 deaths from vCJD in the UK, with another 47 deaths suspected to be due to the disease.
The report is published in the journal Archives of Neurology.