WEDNESDAY, Nov. 5, 2003 (HealthDayNews) -- The mysteriously abnormal proteins that cause the brain-destroying condition called Creutzfeldt-Jakob disease can be found outside the central nervous system, Swiss researchers report.
"The good news is that the availability of highly sensitive techniques for the detection of pathological prions will make it possible to make a firm diagnosis of Creutzfeldt-Jakob disease without resorting to brain biopsy, which to date is the only way to secure diagnosis before the death of the patient," says Dr. Adriano Aguzzi, a professor of pathology at the University of Zurich who reports the finding in the Nov. 6 issue of the New England Journal of Medicine.
"The bad news is that widespread presence of pathological prions in tissues of patients other than brain and spinal cord means that we might have to be even more careful than we used to be, when contemplating the transmission of prions by surgical instruments," he adds.
Creutzfeldt-Jakob disease (CJD) is a member of a family of degenerative nervous system diseases called spongiform encephalopathies, in which tiny holes suddenly riddle the brain, destroying mental function. A widely publicized member of the group is variant CJD, the human version of "mad cow disease," which has led to destruction of millions of cattle in Europe.
These conditions are attributed to prions, protein fragments with virus-like activity. Creutzfeldt-Jakob disease is believed to occur when some unknown factor causes normal proteins to become infective prions. It is generally believed to be a rare condition, with an estimated incidence of one in a million adults, although Aguzzi reports "an alarming increase in the incidence of Creutzfeldt-Jakob disease in Switzerland."
The disease is more common in older people, and autopsies have found in it some patients diagnosed with Alzheimer's disease.
Aguzzi and his colleagues did their work at the National Reference Center for Prion Diseases at the University of Zurich, using a highly sensitive method of detection to look for evidence of prions in tissue samples from 36 people who died of sporadic CJD, which has no known cause but usually attacks older people. Prions were found in muscle and lymph system cells, although in much lower levels than in brain cells, the researchers say.
Earlier detection of prions would not help living patients, since there is no treatment for the disease. But it would indicate the need for extra care in preventing transmission of the condition by contaminated surgical instruments, Aguzzi says.
"While neurosurgical operations have long been known to present a problem, the current data suggest that peripheral operations may also present some risk," he says.
No extra protective measures are needed in Switzerland, because instruments used for surgery on Creutzfeldt-Jakob patients already are sterilized by boiling at extra-high temperatures, he says.
"However, I could imagine that certain other countries may wish to revisit their policies," Aguzzi says.
The test used to detect the prions "can in principle be mastered after one to two weeks of training," Aguzzi says. His laboratory is offering a course on the technique, under sponsorship of the European Molecular Biology Organization.
But the test should be used only in laboratories with the most stringent set of precautions in handling microbes "because of the inherent danger represented by biochemical manipulation of prions," Aguzzi says.
More information
An overview of Creutzfeldt-Jakob disease can be found at the National Institute of Neurological Diseases and Stroke or Britain's National Health Service.
