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    Infectious Disease Prevention Section
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Frequently Asked Questions

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What is CJD?
Creutzfeldt-Jakob Disease (CJD) is a brain disorder that usually occurs in people over the age of 60. It is sometimes called a “spongiform” disease because the brain may develop holes in it like a sponge. Sporadic CJD occurs spontaneously and is the most common type of CJD in the United States. Familial CJD is inherited through a genetic mutation. Iatrogenic CJD is acquired through contamination of neurosurgical instruments or stereotactic depth electrodes, corneal transplants, dura mater grafts, or by administration of contaminated pituitary hormones. Every year about one to two persons out of every million is diagnosed with CJD; most cases are sporadic CJD. There is no known treatment, and most people die within 3 to 12 months of onset of symptoms. Variant CJD, associated with eating beef from cattle with bovine spongiform encephalopathy (“mad cow disease”) is very rare; only 4 cases have been identified in the United States.

What Are Signs And Symptoms of CJD?
At first, CJD can seem a lot like other diseases of the elderly. Symptoms can include dementia, which is difficulty with concentrating, memory or thinking, as well as behavioral changes, mood changes, and changes in sleeping patterns. Patients may lose their balance or seem uncoordinated; they may have difficulty walking or have muscle jerks and spasms. 

Is there a test for CJD?
Yes, there are multiple tests that are available. To confirm CJD, brain tissue must be examined, which can be done after an autopsy, or a brain biopsy, though brain biopsies cannot rule out CJD and are only recommended if a doctor is trying to exclude an alternative treatable disease. The National Prion Disease Pathology Surveillance Center (NPDPSC) provides free autopsy arrangement and tissue examination.

When a doctor is evaluating a patient with symptoms of CJD, other special testing is available. This testing includes cerebrospinal fluid (CSF) tests for 14–3–3 protein, total Tau protein, or RT-QuIC, and blood tests for genetic mutation testing. CSF and genetic blood testing are available at the National Prion Disease Pathology Surveillance Center. A brain MRI can be performed and may show changes that are suggestive of CJD. An EEG (or electroencephalogram), which measures electrical activity in the brain and records brain wave patterns, can also be helpful with the diagnosis.

What Causes CJD?
The current theory for the development of CJD is that an abnormal prion protein converts a normal prion protein to the abnormal form, leading to destruction of brain tissue and giving it a sponge like appearance under the microscope.

How Do You Get CJD?
Most cases of CJD are sporadic CJD, and it is not known how most people get this rare disease, although we do know you do not get it from being around someone with CJD. Approximately 5–15 percent of cases are inherited (familial CJD) and a few cases have been related to transplants of contaminated tissues, use of contaminated neurosurgical instruments, or taking contaminated pituitary hormones (iatrogenic CJD). In 1995, the first case of variant CJD was recognized in the United Kingdom and has been linked to ingestion of beef infected with “mad cow disease”, or receiving a transfusion of contaminated blood or plasma.

Have There Been Any Cases of “Mad Cow Disease” in the United States?
Bovine spongiform encephalopathy (BSE) or “mad cow disease” is a disease specific to cattle. There are different forms of BSE categorized as “classical” and “atypical” (H-type and L-type). Classical BSE is thought to be responsible for the outbreak in the United Kingdom. The primary source of infection for classical BSE is feed contaminated with the infectious prion agent, such as meat-and-bone meal containing protein derived from rendered infected cattle. Regulations from the Food and Drug Administration (FDA) have prohibited the inclusion of mammalian protein in feed for cattle and other ruminants since 1997 and have also prohibited high risk tissue materials in all animal feed since 2009. Classical BSE has not been identified in any U.S.-born cattle. The atypical BSE forms, H-type and L-type, appear to occur spontaneously at very low levels in all cattle populations, particularly in older cattle, and do not seem to be associated with contaminated feed. 

Per the United States Department of Agriculture (USDA), to date, there have been six cases of BSE identified in cattle in the United States. The first case of BSE was a classical BSE case identified in a Washington State dairy cow in 2003 that was imported from Canada (non-U.S. born). Most of the BSE cases in Canada are associated with the classical form seen in the UK outbreak that is linked to vCJD in humans. The subsequent five cases were confirmed atypical BSE in native US born cattle. In 2005, the second reported case of BSE was identified in a 12-year-old Texas beef cow representing the first native born case in the United States. In 2006, the third case was reported in a 10-year-old Alabama beef cow. In 2012, the fourth case of BSE was reported in a 10-year-old California dairy cow. In 2017, the fifth reported case was an 11-year-old Alabama beef cow. In 2018, the sixth reported case was a 6-year-old Florida beef cow.  

Have There Been Any Cases of Variant CJD in the United States?
Yes, there have been four cases of variant CJD identified in humans in the United States. However, there is strong evidence to suggest the first and second case were exposed in the United Kingdom while residing in the United Kingdom during the defined period of risk (1980–1996), the third was exposed in Saudi Arabia, and the fourth it is less clear as to which overseas country the exposure occurred. Additional information about each case is below.

First case - The patient was born in the United Kingdom in the late 1970s and lived there until relocating to Florida in 1992. Onset of symptoms began in 2001 and the patient died in 2004.

Second case – The patient was born and raised in the United Kingdom before moving to Texas in 2001. Symptoms began in 2005, and the patient then returned to the United Kingdom. The case was confirmed neuropathologically (by autopsy) in 2006 by experts in the United Kingdom.

Third case – The patient was born and raised in Saudi Arabia and resided in the United States since 2005. Symptoms began in 2006, and variant CJD was neuropathologically confirmed by biopsy in 2006. Investigators believe that exposure most likely occurred from consumption of contaminated beef imported from the UK while residing in Saudi Arabia as a child.

Fourth case – The Texas Department of State Health Services (DSHS), in conjunction with the CDC, completed the investigation of the fourth vCJD case in the United States. Symptoms began in 2012, and the patient died 18 months later. The investigation confirmed the affected individual was born outside the United States and indicated exposure to the BSE agent most likely occurred before moving to the United States; the individual previously resided in Lebanon, Kuwait, and Russia. The investigation did not support frequent travel or travel of any significant duration to European countries. In absence of a definitive travel link to a country where other known vCJD cases were likely infected, it is less clear as to which specific overseas country the individual’s exposure occurred. The neuropathological analysis performed by the National Prion Disease Pathology Surveillance Center (NPDPSC) at Case Western Reserve University ( confirmed the clinical diagnosis of vCJD.

For additional information, please see CDC’s vCJD Cases Reported in the US website.

Current worldwide vCJD case counts

Are any other animal prion diseases being monitored?
Yes, other animal prion diseases are being monitored by multiple federal and state agencies in the United States. This includes BSE (see above), scrapie in sheep and goats, and chronic wasting disease (CWD) in cervids.

Per the National Institutes of Health (NIH), scrapie was first recognized almost 300 years ago, and after extensive research, there is no evidence that scrapie can infect humans.

CWD was first recognized in Colorado in 1967 and has been found in various states in the US and several Canadian provinces, as well as Norway, Finland, Sweden, and South Korea. CWD has been found in multiple types of cervids, including deer, elk, moose, and reindeer. CWD was identified in Texas in 2012. In Texas, CWD is being monitored by the Texas Parks and Wildlife Department and the Texas Animal Health Commission. Currently, there is no evidence of CWD infecting humans. However, the World Health Organization recommends that agents of prion diseases not enter the human food chain. CDC also recommends that hunters that are hunting in areas with CWD strongly consider having animals tested before eating the meat, and generally recommends not handling or eating meat from animals that look sick, are acting strangely, or are found dead. Please see the CWD section on the Resources tab for links to additional recommendations for hunters. Studies are ongoing to collect information that could help determine if any prion diseases could be occurring at a higher rate in people who are at increased risk for contact with potentially CWD-infected deer or elk. Because of the long time it could take before any symptoms of disease to appear, scientists expect studies to take many years before they will determine what the risk, if any, of CWD is to people.

Last updated July 22, 2021