Mad cow disease has claimed its fourth victim ever in the United States after affecting a resident of Texas, officials report.

The Texas Department of State Health Services (TDSHS) announced this week that laboratory testing conducted in collaboration with the US Centers for Disease Control and Prevention (CDC) has confirmed that a man who died last month of an unknown illness had died of variant Creutzfeldt-Jakob Disease (vCJD) - the human form of mad cow disease.

In a statement on Tuesday, the CDC pointed out that it's likely that this is an isolated case of the disease, and poses no threat to the general populous.

Three previous cases of vCJD that caused deaths in the United States were all associated with international travel, and were not thought to have originated from US food supplies. Two of these cases were found connected to the United Kingdom - where 177 cases of the world's estimated 220 cases in all were reported. The other patient was tied to travel in Saudi Arabia, where it's suspected the disease is prevalent (in respect to other regions' infection rates), but widely unreported.

"The history of this fourth patient, including extensive travel to Europe and the Middle East, supports the likelihood that infection occurred outside the United States," CDC investigators concluded.

According to the TDSHS, vCJD rapidly affects the brain, causing loss of speech, understanding, and other symptoms similar to rapid dementia and brain damage. It makes up 85 to 95 percent of all kinds of CJD cases and is sometimes referred to as "classic" human mad cow disease.

The disease tends to take 13 months to progress, but as there is no cure for it, the inevitable neurodegredation caused by the disease always proves fatal.

The CDC and TDSHS have estimated that vCJD disease affects up to 1.5 people per million inhabitants each year. However, the disease remains "underreported and misdiagnosed" even in the United States. That, coupled with the fact that it often cannot be confirmed until after death, has led the number of reported cases to lag significantly behind estimates.