100% fatal brain disease strikes 3 people in Oregon

Three cases of a mad cow-like disease with a 100% fatality rate have been reported in a single county in Oregon.

Within the last eight months, health officials have confirmed one case and identified two probable cases of the rare brain disease, according to a statement released by the Hood River County Health Department on April 14. Hood River County is located south of the Columbia River on the Washington-Oregon border. Two of the people with the condition have died, the department reported.

One case was confirmed by autopsy, while the other two are presumptive, The Oregonian reported. Trish Elliott, director of the health department, told The Oregonian that the presumptive cases can only be confirmed after death by examining brain tissue and cerebrospinal fluid — the clear fluid that surrounds the brain and spinal cord — and she said this process can take months.

"At this time, there is no identifiable link between these three cases," the health department added.

The mad cow-like disease reported in Oregon is called Creutzfeldt-Jakob disease (CJD), named for two German doctors who first described the condition in the 1920s. The disease impacts around 1 to 2 people per million worldwide, and the United States sees roughly 350 cases a year. About 23,000 to 24,000 people live in Hood River County, according to census data, so seeing three CJD cases crop up is statistically unusual.

Related: Here's how dangerous, deadly prions spread to the brain

Like mad cow, CJD is a prion disease, meaning it's caused by abnormally folded proteins that damage brain tissue; in CJD, this causes sponge-like holes to form in the brain. The prions also cause normal proteins in the brain to turncoat, transforming into prions that then inflict further damage.

The disease can cause a slew of symptoms, including confusion, disorientation, hallucinations, lack of coordination and muscle stiffness, along with personality changes, new-onset psychological problems, and seizures. The symptoms progress quickly, leaving people with the disease unaware of their surroundings and unable to communicate. The disease is always fatal, with about 70% of those affected dying within a year of diagnosis.

The most common type of CJD is "sporadic," meaning normal proteins in the brain spontaneously transform into prions for unknown reasons. The next most common type is genetic, triggered by inherited mutations in a gene called PRNP. The gene carries instructions to make prion protein (PrP), which is known to be active in the brain but whose normal functions aren't fully understood. Some studies suggest the normal version of PrP may help protect neurons from injury and form connections between neurons.

Perhaps the most famous form of CJD is the rarest, however, accounting for less than 1% of cases. It involves prions entering the body from external sources. For instance, this can occur if a person eats beef from cows that have bovine spongiform encephalopathy (BSE), better known as "mad cow disease;" only seven cases of BSE have ever been detected among cows in the U.S. Another potential source of prions is through medical exposures, such as a person getting a transplant or blood transfusion from a donor with CJD.

To prevent cases of "acquired" CJD, the U.S. has had strict agricultural regulations in place since the 1990s to keep mad cow-affected beef out of the food supply. There are also infection control guidelines to prevent the transmission of CJD through medical procedures.

The Hood River County Health Department has not announced which type of CJD is likely implicated in the recent cases, but Elliott told The Oregonian that they don't think infected cattle are the cause. And again, it appears that the three cases aren't linked to one another, the department noted.

"The risk of getting CJD is extremely low," the department's statement emphasized. "It does not spread through the air, touch, social contact, or water."

The department is conducting an "active and ongoing investigation" of the cases and has partnered with Oregon Health Authority and the Centers for Disease Control and Prevention. "The health department will continue to monitor the situation and keep you informed of any risk to public health."