The seven cases of the fatal neurodegenerative disease were reported to the UK CJD surveillance system.
This monitors all cases of CJD arising sporadically, genetically, and as a result of infection from contaminated food products (variant form) or surgery (iatrogenic).
The seven cases reported between 1970 and 2003 were the result of inadvertent transmission via transplanted human dura mater.
Dura mater is the outermost, toughest, and most fibrous of the three membranes covering the brain and spinal cord. It is used in cranial and spinal surgical repair, and in various other procedures, such as the reinforcement of tendons and ligaments.
CJD arose between four and 15 years after surgery, and was traced to one particular supplier in six of the seven cases. In the remaining case, the source was traced to pig tissue, and is believed to be the first such case in the world.
The authors emphasise that transmission of CJD though the use of transplanted human dura mater is rare. Only 164 such cases have been identified around the globe, and most of these were treated with the product identified as the primary source in the UK cases.
The risk to patients in the UK is unknown, say the authors, but research from Australia puts the risk as high as 1 in 500 for those treated between 1973 and 2003.
In Japan, where some 20,000 human mater dura grafts are performed every year, the risk is put at between 1 in 1000 and 1 in 2000.
More stringent selection criteria and better disinfection techniques introduced since 1987 may help to reduce the numbers of future cases arising from surgical transplants, suggest the authors.