Recently we have learned that 15 patients in New England were exposed to a rare infection called Creutzfeldt-Jakob disease (CJD) when neurosurgical instruments contaminated with the infection were used in their care. Each had undergone a brain or spinal surgery in early 2013, and now their future was uncertain.

Creutzfeldt-Jakob disease is caused by an infectious agent called a prion — as is “mad cow disease.” Originally discovered in the brain-eating Fore cannibals of Papua New Guinea, prions are misshapen proteins that are the vampires of the protein world. Prions cozy up to normal human proteins and convert them into misshapen proteins themselves. These new prion converts can then turn additional human proteins into misshapen proteins, and a chain reaction sets up. Eventually the accumulation of misshapen proteins crowds out the normal contents of brain cells, spongy deposits of protein litter the tissues of the brain, and victims of prion diseases develop what is called spongiform encephalopathy.

Since prions are resistant to standard sterilization techniques, neurosurgeons can transmit CJD from patient to patient. For instance, doctors might harvest tissue from the nervous system of an organ donor not recognized to have CJD and then the graft recipient will succumb to the infection years later. Early cases of CJD were diagnosed in recipients of human growth hormone derived from ground up pituitary glands. Others developed CJD from contaminated brain electrodes. In all of history, there have been only four reported cases of CJD in patients whose sole risk was to undergo a neurosurgical procedure with instruments contaminated with the infection. However, the discovery that surgical instruments contaminated with CJD still cause an uproar: at Emory Hospital in 2004, fully 98 patients were exposed to contaminated surgical instruments and the group is still being monitored for signs of disease.

Creutzfeldt-Jakob disease takes years to develop. Patients exposed to the infection feel fine for years but then they become moodier and forgetful and over the course of months subtle cognitive defects progress to severe dementia. Patients with CJD forget the names and faces of loved ones, they lose the ability to walk, speak, or swallow, and they lapse into a coma that has proven fatal one hundred percent of the time.

To avoid neurosurgical prion transmission, the instruments used in a patient suspected to have CJD should be destroyed or specially decontaminated. With such measures in practice, it has been thirty years since a case of CJD was attributed to contaminated surgical instruments. At Catholic Medical Center in Manchester, New Hampshire, though, the instruments used to biopsy the patient later diagnosed with CJD were sterilized via standard techniques and put back into use.

When Creutzfeldt-Jakob disease contamination of surgical instruments is discovered, doctors at Catholic Medical Center and other hospitals wonder if it is right to tell patients. In most cases the disease will never occur and there is no effective means of prevention. Even for the unlucky patients who do develop the disease — if any of them do — there is no effective therapy so advance warning gives no extra measure of hope. Worse still, there is no diagnostic test to predict who will escape infection or die, so the only thing patients can do once notified is wait. That means the only real world impact of disclosure, regardless of the eventual outcome, is patient distress. So in this case is knowledge power, or is knowledge just knowledge?

Beyond the desire not to worry patients unnecessarily, Catholic Medical Center doctors were likely tempted to hide the error in sterilization technique. Yet doctors value transparency and trusting relationships with patients, and most patients want to be notified if physicians make an error or discover an abnormal finding incidentally.

Like the 98 patients at Emory, eight patients at Catholic Medical Center in New Hampshire who were exposed to Creutzfeldt-Jakob disease were notified last week, and counseled that they will have to wait years to find out if they contracted the infection. At Cape Cod Hospital in Massachusetts and the West Haven Veterans Affairs Hospital in Connecticut, which rented the same neurosurgical instruments from Catholic Medical Center, seven additional patients will join in the wait. Fortunately, whether or not patient notification was a good idea, surveys show that patients do not suffer serious long-term distress after learning they were exposed to surgical instruments contaminated by prions. Few of us can maintain a state of high alert for very long in response to a risk that is both minuscule and abstract.

Dean Foster and colleagues at the University of Pennsylvania devised a free online calculator that estimates life expectancy based on demographics, habits and family history. Punch in the facts and out pops an estimate. Not surprisingly, smokers and drinkers are predicted to live shorter lives, whereas people in low stress jobs who get a lot of exercise live longer. Or at least that is what the calculator says.

But no online calculator can predict lightning, terrorists, and other random calamities. None asks, after assessing alcohol consumption and seat belt use, “Do you expect to be notified your neurosurgical procedure was contaminated by a rare prion disease?” That means that by their calculation, beyond eating our broccoli and squeezing in a run from time to time, we really cannot know the day of our demise.

The question then is whether there is something, anything, to be gained from knowing that somewhere deep in the brain a rampaging misshapen protein with an appetite for global domination is quietly, mercilessly, taking apart the very substance of who you are. Or not. Personally I would rather live without that kind of shadow hanging over me.

Timothy Lahey is an infectious disease physician and medical ethicist who blogs at [M U R M U R S].  This article originally appeared in The Atlantic.