Officials in Marin, California had recently reported two cases of Creutzfeldt-Jakob Disease (CJD).  CJD is a rare and fatal brain disease.  One type of CJD is   Bovine spongiform encephalopathy (BSE), sometimes referred to as “mad cow”disease.

Lab results results released today though, indicate that, for at least one of the cases, there is no indication of “mad cow” disease: 

Laboratory tests have confirmed that at least one of the two cases of Creutzfeldt-Jakob disease diagnosed recently in Marin is not the variety linked to mad cow disease.  “That is definitive,” Dr. Craig Lindquist, Marin County’s interim public health officer, said Thursday morning.  California Department of Public Health officials notified Lindquist on Friday that two Marin residents had recently been diagnosed with Creutzfeldt-Jakob disease and one of them had died due to the exceedingly rare, fatal illness.  “This is the case of the individual who is deceased,” Lindquist said. He declined to identify the victim or where in Marin the person lived.

BSE is a chronic degenerative nervous system disease affecting cattle. The disease was first diagnosed in 1986 in Great Britain. BSE is so named because of the spongy appearance of the brain tissue of infected cattle when sections are examined under a microscope.

The incubation period (the time from when an animal becomes infected until it first shows signs of disease) is from 2 to 8 years. Following the onset of clinical signs, the animal’s condition deteriorates until it dies. Currently, there is no test to detect the disease in a live animal; veterinary pathologists confirm BSE by postmortem microscopic examination of brain tissue or by the detection of the abnormal form of the prion protein.

Since November 1986, over 178,000 head of cattle have been diagnosed with BSE in Great Britain. The epidemic peaked in January 1993 at approximately 1,000 new cases reported per week.