Luckily, prion disease in humans is rare, like one in million. However, the rapid spread through wild game animals and the history of transmission of a similar disease to humans from eating prion-infected beef means knowing about the disease is important.
Misfolded proteins called prions cause a group of deadly neurodegenerative disorders in humans called Creutzfeldt-Jakob Disease (CJD), named for the men who first described them. Three main forms are:
* Sporadic CJD – most common (85% of cases), unknown source/cause but the microscopic prion structure is like the type in sheep
* Hereditary CJD – 10% of cases; in families with a history of the disease and test positive for a genetic mutation
* Acquired CJD – transmitted by medical procedures or eating contaminated meat, or as in kuru from cannibalism.
The diseases are collectively known as Transmissible Spongiform Encephalopathies (TSEs) in animals, a descriptive term depicting the holes in brain tissue from abnormal protein accumulation. CJD is the most common of human prion disease; others include Fatal Familial insomnia (FFI), and Gerstmann-Straussler-Scheinker disease (GSS).
Symptoms of CJD
Neurologic symptoms in cattle bear some resemblance to prion-infected humans. Variant Creutzfeldt – Jakob (vCJD), the human form caused by mad cow prions, begins with visual changes, color variation and distortion of figures. Progression occurs over months and is varied depending on the area of brain most affected.
Symptoms include emotional instability, (crying, laughing, anger outbursts), visual hallucinations, slow thinking, memory loss, and impaired judgment. As the disease worsens, tremors, poor balance, stiffness and jerking muscles cause trouble walking. Ultimately, the person is bedridden and lapses into a coma. Symptoms overlap with other neurodegenerative diseases including Alzheimer’s and Parkinson’s.
Neurological evaluations for these symptoms often include brain MRI or CT scans and spinal fluid testing. A brain biopsy provides the definitive diagnosis, but new blood and urine tests are available. Microscopic findings show characteristic protein accumulations with holes, making brain tissue look like a sponge. To identify the origin of the disease, differences in the abnormal folding of prion proteins can be determined at the Human Prion Surveillance Center in Cleveland, Ohio.
We have hope for rapid diagnosis and treatment with researchers around the world and in Montana at the NIH Rocky Mountain Lab in Hamilton, searching for ways to stop prion disease. The current concern is saving the wildlife.
More information can be found online at the NIH Fact Sheet website:
I am finishing final editing on Extinction, a prion medical thriller and will soon be ready to query agents.
Thanks for stopping by.
Betty Kuffel, MD