A rare and fatal brain disease with a 100% mortality rate has gripped Hood River County, Oregon, raising concerns within the medical community and eliciting intense probes by local and federal health officials. It is called Creutzfeldt-Jakob Disease (CJD), and it has killed two people and impacted a third in eight months—a terrifying cluster in a county of only slightly more than 23,000 people.On April 14, the Hood River County Health Department reported one case of Creutzfeldt-Jakob Disease and two more probable cases. Although only one case has been confirmed by a diagnosis through an autopsy, the other two are presumptive and await post-mortem confirmation through examination of brain tissue and cerebrospinal fluid. Such examination, as explained by Trish Elliott, Director of the Hood River County Health Department, may take months.Although the origins of these three cases are still unknown, the cluster is epidemiologically significant. The U.S. experiences about 350 cases of CJD each year, or 1 to 2 cases per million individuals globally. For Hood River County, with only 23,000 people, to see three cases over such a brief time span is an epidemiologic outlier.What Is Creutzfeldt-Jakob Disease (CJD)?Creutzfeldt-Jakob Disease is a rapidly advancing and always lethal neurodegenerative disease resulting from misfolded proteins known as prions. Initially documented in the 1920s by German physicians Hans Gerhard Creutzfeldt and Alfons Jakob, CJD causes sponge-like holes to form within the brain, destroying its structure and function.CJD is a member of the larger family of prion diseases, which also encompasses other rare but fatal disorders like kuru and fatal familial insomnia. Similar to bovine spongiform encephalopathy (BSE), commonly referred to as mad cow disease, CJD irreversibly destroys the brain and has no cure.CJD Symptoms and ProgressionThe symptoms of CJD are extreme and worsen quickly. Early symptoms may involve confusion, disorientation, personality changes, memory loss, visual disturbances, and stiffness of the muscles. Later in the disease, patients can develop hallucinations, difficulty speaking or swallowing, seizures, and sudden jerky movements.Death typically occurs within a year of the onset of symptoms, usually as a result of complications such as pneumonia, heart failure, or problems arising from neurological deterioration such as falls and choking.Symptoms in the early stages of sporadic CJD usually resemble other dementias but worsen with terrifying rapidity. The majority of individuals with sporadic CJD are between 50 and 80 years of age, but some genetic forms can occur earlier, even in some people as young as 30.Various Types of CJDCJD comes in several types:Sporadic CJD (sCJD): This type is the most prevalent, affecting about 85% of the cases. This type happens spontaneously when healthy proteins in the brain misfolded into prions for unknown reasons.Genetic CJD (fCJD): Due to mutations in the PRNP gene, this form is inherited and represents about 10–15% of the total cases. The PRNP gene codes for the prion protein (PrP), a protein involved in neuronal communication and protection.Acquired CJD (also referred to as iatrogenic or variant CJD): This is a rare type that involves outside sources of infection, such as eating infected beef (BSE/mad cow disease) or through tainted medical equipment or transplanted tissue.In spite of concerns, authorities from Hood River County stressed that the present cases do not seem to have resulted from infected cows. "At this point in time, there is no cause identified between these three cases," the department noted. They also pointed out that CJD cannot be transmitted via air, touching, social contact, or water.Public Health Measures and Continued InvestigationsThe Hood River County Health Department, in collaboration with the Oregon Health Authority and the Centers for Disease Control and Prevention (CDC), has launched an "active and ongoing investigation" into the three reported cases.“We’re trying to look at any common risk factors that might link these cases,” Trish Elliott told The Oregonian. “But it’s pretty hard in some cases to come up with what the real cause is.”Although risk to the general population is "extremely low," the health department continues to monitor it. Since CJD cannot be definitely diagnosed until after death, real-time monitoring is not easy, and so robust surveillance is essential.Can CJD Be Prevented?Although there is no treatment or cure to prevent the development of CJD, the U.S. has established strict public health measures to minimize the risk of acquired CJD, especially through food supply control and medical safety measures.Federal authorities have maintained since the 1990s a prohibition against feeding cattle which could be contaminated with BSE, and employment of high-risk material in foods is strictly barred. Sterilization processes of surgical devices as well as strict donor screening in transplantation and transfusions are all undertaken to cut back on iatrogenic spread.While medical officials wait for further verification and possible connections between the three patients, the attention is on education, surveillance, and reassurance to the public.Although it is reassuringly ominous to witness a disease of this kind emerging in a small American community, the risk at the international level remains low, especially with measures presently in place. Nevertheless, the cases are a sobering reminder of the enigma that prion diseases continue to pose to modern medicine.Health officials are still keeping an eye on the matter and are asking people not to panic but to remain updated. "The health department will remain vigilant and inform you of any public health risk," officials promised in a statement.