The U.S. Centers for Disease Control and Prevention announced earlier this week that a Texas man died last month from Variant Creutzfeldt-Jakob Disease (vCJD), bringing the total number of deaths from vCJD to four since the disease was first characterized in the United Kingdom in 1996. The confirmation of vCJD was made by laboratory testing of the man’s brain collected during autopsy. An investigation into how the man may have contracted the disease is still ongoing.

Variant CJD is a rare, degenerative and fatal brain disease in humans that is thought to be caused by the consumption of beef positive for bovine spongiform encephalopathy (BSE), more commonly known as mad cow disease. The two diseases are caused by prions, which are misfolded proteins that accumulate and kill brain cells. The symptoms of vCJD include prominent psychiatric and behavior issues and dementia. There is no known cure, and the disease is always fatal.

More than 220 vCJD cases have been reported worldwide, with 177 of these cases documented in the U.K. There have been 27 cases in France. In each of the three previous U.S. cases, infection occurred overseas with two in the U.K. and one in Saudi Arabia. The most recent patient traveled extensively in Europe and the Middle East and is thought to have contracted the disease overseas.

“There is no evidence to suggest that other people in the United States have been exposed to variant CJD because of this patient,” said CDC spokeswoman Christine Pearson.

In addition to the variant form, a sporadic form of CJD is described. Sporadic CJD is not linked to mad cow disease; its precise cause is not known. Sporadic CJD is also fatal, and the symptoms differ slightly from those of vCJD and they come on very rapidly. Each year, approximately one or two per million people develop sporadic CJD.