Mad cow disease in humans is extremely rare and is known as variant Creutzfeldt-Jakob disease (vCJD). It can occur when people eat beef containing infectious prions, typically tissue from the brain or spinal cord of an infected cow. Most reported human cases have been linked to exposure outside the United States, and there is no confirmed, sustained transmission of vCJD through typical meat consumption in the U.S. to date. Classic Creutzfeldt- Jakob disease (CJD) is a separate, sporadic prion disease that occurs worldwide and is not caused by consuming BSE-infected cattle. Key points
- vCJD is the human form of BSE and is associated with prions in neural tissue. It is fatal and progresses over months to years, with early symptoms that can be nonspecific and later neurologic decline.
- BSE (mad cow disease) itself affects cattle and is transmitted to humans only in rare cases via consumption of contaminated neural tissue, not via muscle meat or milk in typical scenarios.
- In the U.S., there have been very few vCJD cases, with all identified patients having lived in or traveled to areas where exposure occurred; no U.S.-originated vCJD case has been linked to locally produced beef.
- Classic CJD is a distinct, sporadic condition occurring globally at a low baseline rate and is not linked to BSE exposure.
If you’re concerned about exposure or symptoms
- Seek medical evaluation if there are rapidly progressive dementia-like symptoms, coordination problems, or behavioral changes, especially with a recent history of exposure that could raise concern for prion diseases. Diagnosis typically involves MRI, spinal fluid testing for prion proteins, and clinical assessment.
- Public health guidance emphasizes preventing exposure to neural tissues in cattle products and monitoring food safety practices; the risk to the general public remains extremely low.
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