A Marin County woman has died and a second resident is sick with a rare degenerative brain disorder that is occasionally associated with mad- cow disease, but neither case is infectious and there is no public health threat, state officials said Thursday.
Both patients have been diagnosed with Creutzfeldt-Jakob disease, which is marked by a buildup of damaged proteins in the brain and causes early dementia. Creutzfeldt-Jakob disease is always fatal, usually within a year of diagnosis.
Lab tests released Thursday confirmed that one of the cases was definitely not the “mad cow” form of Creutzfeldt-Jakob, and experts in the disease said it is highly unlikely that the second case was related to mad-cow disease.
“We have no evidence that suggests a causal linkage between the suspect cases nor is there any evidence to suggest a risk in food supply,” the state public health department said in a statement.
Marin County public health officials said the cases are under investigation, but noted that there is no risk of the disease spreading.
Creutzfeldt-Jakob disease is rare: There are roughly 300 cases in the United States every year and 30 in California, said experts in the disease at UCSF and Stanford. Most cases come up suddenly and for no known reason, or are inherited.
About 1 percent of cases are known as “acquired” Creutzfeldt-Jakob, and they are usually caused by an infection called bovine spongiform encephalitis, or mad-cow disease. People get the acquired form from eating infected beef or from getting a blood transfusion or tissue transplant from someone who has the disease.