Post mortem examination of a third person infected with variant Creutzfeldt-Jakob Disease (vCJD) through blood transfusion has confirmed the presence of the fatal disease.

Professor John Collinge of the Medical Research Council (MRC) Prion Unit has been tracking 66 people known to have accidentally received infected blood by transfusion. Of these, three are now confirmed to have died from vCJD and 39 from unrelated causes. The remaining 24 are now thought to have a significant risk of contracting the disease.

An update on the study was reported in The Lancet.

Prof Collinge said on BBC Radio 4’s Today Programme earlier today that because three people have now died from this small group, the risk of contracting vCJD through blood transfusion is likely to be “substantial”.

Humans can get vCJD through two routes: by ingesting meat infected with Bovine Spongiform Encephalopathy (BSE, or “mad cow” disease) or from infected humans who give blood or contaminate surgical instruments. This new evidence suggests that human to human transmission leads to much earlier development of full blown vCJD, unlike infection via the BSE route which can lie dormant for up to 50 years.

The danger to the public is that people who ate BSE infected meat as long as 20 years ago could be carrying the vCJD precursor “prions” and passed it on through blood donation before testing was brought in. The donor may not show symptoms for another 20 years, but the recipient may well show symptoms much earlier which is why there are renewed fears of a resurgence of cases following this latest news.

vCJD is a fatal, degenerative brain disease with no cure, although some experimental treatments exist. In humans it is transmitted through infection by prions. Unlike more common forms of infection, prions are not viruses or bacteria but “naked” proteins composed of the same amino acid building blocks as normal brain cell proteins. They have a different shape to normal brain cell proteins and infection spreads because they gradually convert the surrounding proteins into their own shape. This causes brain cells to malfunction and eventually die. The brains of people who die from vCJD and of cows who have died of BSE resemble a swiss cheese filled with spongy masses.

The presence of potential vCJD infectious prions can only be confirmed by brain tissue sampling or post mortem examination (for example of the tonsils), making diagnosis before symptoms of full blown vCJD emerge extremely difficult.

Click here to learn more about prions (NIH).

Written by: Catharine Paddock
Writer: Medical News Today