October 9, 2002 Agence France Presse
German scientists believe they can almost instantly screen blood for
the agent that causes the human form of mad cow disease, an
achievement that could root out the risk of spreading the disorder by
The test devised by a team led by Dieter Naumann at Berlin's Robert Koch Institute can distinguish between healthy and infected blood in under 15 minutes, New Scientist says in next Saturday's issue.
The technique has so far been tested on blood from hamsters infected with scrapie, a brain-destroying disease that is the sister to variant Creutzfeldt-Jakob disease (vCJD) in humans and to bovine spongiform encephalopathy (BSE) in cows. The test picked up 97 percent of all infected samples, with no false positives for healthy blood. The next phase is to extend it to vCJD and BSE.
Other test methods have taken the route of using antibodies to detect the presence of rogue prion proteins, the agent that causes vCJD.
Naumann's system takes a different path, looking instead for "subtle differences in the overall chemical makeup" between infected and healthy samples, New Scientist says.
The distinction is made by a form of chemical analysis called Fourier transform infrared spectroscopy.
It beams infrared radiation on a sample and measures peaks and troughs, comparing that data spectrum against a model of a healthy sample.
The new test is described in full in a specialist journal, Analytical Chemistry.
"The proposed test can be completely automated and potentially requires less than 15 minutes for taking the sample, acquiring the spectrum and attaining the final diagnosis," Naumann's team says.
Britain has recorded 127 cases of definite or probable vCJD, 115 of whom have died, while France has recorded six cases, five of whom have died. Ireland has had one case of vCJD, involving a woman who had lived in Britain.
But there are many unknowns about vCJD, notably the time it takes to incubate before the first symptoms are shown, and there are fears that some people may become infected through blood transfusion.
There is no recorded case of this having happened, and authorities in many countries have already tightened up screening procedures or are filtering out white blood cells from donated blood as a safeguard.
However, New Scientist says that the evidence of transfusion risk is gradually growing.
Four sheep out of 24 that have been given BSE-infected blood in a long-running British experiment have now developed the disease, and it is still unclear whether the infection source lies in plasma or red blood cells, it says.