November 26, 2018Infectious Disease
Prion diseases originate when normally harmless prion protein molecules become abnormal and gather in clusters and filaments in the body and brain. According to the NIH, Creutzfeldt-Jakob disease (CJD) is a rare, degenerative, fatal brain disorder associated with the accumulation of prions in the brain. It affects about one person in every one million per year worldwide and in the United States there are about 350 cases per year. CJD usually appears in later life and runs a rapid course. Typical onset of symptoms occurs at about age 60, and about 70% of individuals die within one year. In the early stages of the disease, people may have failing memory, behavioral changes, lack of coordination, and visual disturbances. As the illness progresses, mental deterioration becomes pronounced and involuntary movements, blindness, weakness of extremities, and coma may occur.
According to an article published in MBio (20 November 2018), the eyes of deceased Creutzfeldt-Jakob disease (CJD) patients show evidence of prions, and that these finding suggests that the eye may be a source for early CJD diagnosis as well as potential safety risks. The study raised questions about the safety of routine eye exams and corneal transplants. Since about 40% of sporadic CJD patients develop eye problems that could lead to an eye exam, meaning the potential exists for the contamination of eye exam equipment designed for repeat use. Further, cadaveric corneal transplants from undiagnosed CJD patients have led to two probable and three possible cases of disease transmission.
Previous studies have shown that the eyes of CJD patients contain infectious prions, though the distribution of prions among the various components of the eye was not known. To address this question, the authors recruited 11 CJD patients who agreed to donate their eyes upon death. Results showed evidence of prion infection throughout the eyes of all 11 deceased patients using real time quaking-induced conversion (RT-QuIC), a highly sensitive test NIAID scientists developed that detects prion seeding activity in a sample as evidence of infection. The RT-QuIC test is used in clinical settings to diagnose sporadic CJD in people.
The authors will continue their work to evaluate accessible eye components or fluids as feasible diagnostic testing sources. They also plan to use other RT-QuIC tests to evaluate the eyes of patients with Alzheimer's, Parkinson's and dementia with Lewy bodies to determine whether infectious proteins from those disease processes are present.