http://www.guardian.co.uk/bse/articl...778641,00.html
Fears increase on transmitting human form of BSE
James Meikle
Friday May 19, 2006
The Guardian
Scientists' concerns about preventing an epidemic of the human form of BSE passed on between people through blood transfusions and contaminated surgical instruments strengthened last night as evidence grew that far more people than once thought are prone to infection. Research involving human tissue is confirming suspicions raised from animal tests that people of all genetic types can have the rogue prion protein associated with the disease, not just the group from which all those so far struck with the incurable neurological disease have come.
While relatively few people have died from eating meat contaminated with BSE, because the disease had to cross a species barrier from cattle, transmission of infection between people may be far easier.
The idea is increasingly worrying scientists because there is no blood or other test that can identify infection before patients show any symptoms of the long-incubating incurable disease. Two people are already thought to have developed vCJD because of blood transfusion and a third has shown signs of infection in her spleen and lymph nodes, despite dying of other causes.
The 161 Britons who have had obvious disease are thought to have all come from one genetic type represented in about 40% of the population. But the woman who died from other causes came from another genetic group, and now rogue prions have been found in the third and last group. They are distinguished by differences in one particular part of the prion protein gene.
Tests on two appendices removed from patients who were in their 20s at the time found the prions in the third genetic group. They were among three apparently infected organs out of more than 11,000 removed from patients during the late 1990s. But scientists reporting findings in the British Medical Journal today urge caution in interpreting them.
Big changes have already been made to blood transfusions because of fears of transmitting the disease between people and further changes to dental and surgical practices are likely. But health experts fret that continuing to restrict supply of blood donors and the expense of introducing disposable surgical equipment might be taking precautions too far.
James Ironside, of the CJD surveillance unit, Edinburgh, and lead author of the study, said: "Human exposure to BSE in the 1980s and early 1990s was extensive in the UK, yet we have seen relatively few cases of vCJD. Either things like the species barrier were more protective [of humans] than we thought, or there have been more infections than have so far been clinically manifested. If secondary transmission is extensive enough, it could lead to a vCJD problem that would be very difficult to get rid of." The latest brick in the wall scientists are building in understanding vCJD comes as government advisers consider ways of screening people through postmortems to see how much "hidden" vCJD there is.
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