A recent victim of a rare, fatal neurogenerative condition called Creutzfeldt-Jakob disease (CJD) likely contracted the illness by eating infected squirrel brains, according to research by staff at the Rochester Regional Health hospital.

The 61-year-old man was one of five suspected and three confirmed CJD patients treated at the medical center between 2013 and 2018, prompting an investigation into how providers can better recognize the condition’s early signs, and therefore quarantine anyone who may be carrying the transmissible form. Their case analysis was presented earlier this month at IDWeek 2018, an international conference on infectious diseases.

CJD is one of a handful of disturbing, untreatable brain disorders within the category of prion diseases. Though much about the underlying mechanisms remain poorly understood, prion diseases are known to arise when a certain protein found on many types of cells begins to misfold in the brain, arranging itself into a non-functional clump. These abnormal proteins then induce normal versions of the prion protein to convert shape, setting off an as-of-yet irreversible feedback loop that results in toxic accumulations of the infectious proteins. 

While acquired CJD is the least common form of an uncommon disease – representing fewer than 1 percent of the 7,000 or so worldwide cases per year – it is the most well-known thanks to its headline-grabbing subtype, variant CJD (vCJD).

In vCJD, humans "acquire" misfolded prions by ingesting brain tissue from animals infected with non-human prion disease, such as scrapie – which affects sheep and goats – or “mad cow disease”. According to Live Science, there have only been a few hundred reported cases of vCJD, and most of these were tied to several waves of contaminated ground beef produced and sold in the 1980s and 90s.

All forms of CJD are characterized by rapid loss of motor control and muscle function, vision loss, dementia, and personality changes. Eventually, those afflicted will lose their ability to move or speak, enter a comatose state, then die. Variant CJD differs slightly from the hereditary form in that it usually presents with psychiatric changes before the other symptoms arise and does not kill as quickly.

Given the rarity of CJD, physicians at Rochester Regional Health were alarmed when four patients displaying the hallmark signs presented to the hospital during a six-month period between November 2017 and April 2018. In response, a team led by Dr Tara Chen reviewed the facility’s records for any additional cases in the past five years, leading to the identification of a total of five cases. Of the three diagnosed cases, two were believed to be sporadic CJD based on features seen on MRI scans. One patient died three months after symptoms began, and, surprisingly, one is still alive more than 12 months later.

The 61-year-old male, who was already delirious by the time he was brought in, was also diagnosed with CJD by MRI scan. But it was during a patient history taken with his family members that the team pinpointed the probable cause of his vCJD: the man apparently liked to hunt and had eaten squirrel brains in the past. Sadly, the man died after five months. Because the only foolproof way to confirm CJD is with a brain tissue analysis, Dr Chen and her team are currently working to see if this was conducted at the time of his death and if its findings can be examined. If confirmed, it will mark just the 5th case of vCJD reported in the US.

[H/T: Live Science]