New research on a fatal brain infection related to mad cow disease could lead to safe ways to diagnose the infection through the eyes. The findings are also a red flag about the importance of preventing the spread of the infection during eye surgery and other procedures, researchers said.
It was already known that a rare and fatal brain infection, called Creutzfeldt-Jakob disease, has been found in the corneas of people who died from the disease. The disease’s infectious cells are called prions. A new study found these prions in tissue throughout the eyes.
There is no cure for Creutzfeldt-Jakob and no test for it in people who may be infected. Currently, it’s only diagnosed after death by examining brain tissue.
Creutzfeldt-Jakob is extremely rare. It affects one in one million people annually, according to the National Institutes of Health. Most of the time, the disease occurs in people with no risk factors. Some cases are linked to an inherited gene.
The rarest type of the disease is the contagious form. The disease can spread through direct tissue-to-tissue contact in medical procedures or on contaminated medical equipment. It’s believed that another rare version of Creutzfeldt-Jakob is passed to humans who eat meat from cows infected with bovine spongiform encephalopathy, commonly called mad cow disease.
There’s no evidence that the disease is spread through casual contact. It doesn’t pass through the air, or by shared bedding, toilet seats, hairbrushes or towels.
In the new study, researchers at the National Institute of Allergy and Infectious Diseases, at the University of California-San Diego, and the University of California-San Francisco Medical Center examined the eye tissue of 11 people who died from Creutzfeldt-Jakob.
They looked at many parts of the eye, including the cornea, lens and retina. Creutzfeldt-Jakob prions were found in eye tissue of all of the patients.
The recent study is the first to show infected cells throughout the eye. It also looked at the largest number of patients to date.
Symptoms of the disease usually don’t show up until older age, after 60. They include dementia, personality change and vision problems. Once symptoms are acute, people usually die within a year.
Ophthalmologist and cornea expert Natasha Herz, MD, of Rockville, Maryland, said that medical safety regulations are designed with the highest standards to prevent the spread of infection. The standards apply to equipment sterilization, protective clothing such as gloves and masks, and organ and blood donor testing.
The goal is to protect patients, doctors and clinical staff.
Herz has confidence in current safety standards. But the recent study, she said, is a wake-up call to safety experts to make sure they’re paying close attention to Creutzfeldt-Jakob and to adjust their standards accordingly.
These standards apply to eye doctors, other medical doctors and organ donor banks. “Certainly eye banks need to pay attention to this very carefully,” Herz said. Her medical practice includes doing corneal transplants.
Meanwhile, she stressed, patients shouldn’t panic. The bottom line is that the disease is extremely rare, and not easily transmitted.
The California study shows promising progress in the ability to examine eye tissue, she added. “I’m encouraged by the fact that they have come up with a reliable test of checking for those prions. That would say to me that they’re going to be pretty successful in screening transplant tissue for the disease.”
The study research also shows a pressing need for more research on Creutzfeldt-Jakob and the eyes, Herz said. Many studies are showing a strong relationship between eye tissue and brain tissue, connected through the central nervous system.