Idaho probes outbreak of Creutzfeldt-Jakob disease
Idaho officials on Friday confirmed one case of naturally occurring Creutzfeldt-Jakob disease (CJD) and are investigating five other suspected cases, but said none are believed to be caused by eating infected animals.
CJD is a rare brain-wasting disease in humans that usually affects older people in their 60s or 70s. It is not the same as the human form of mad cow disease, which is known as variant Creutzfeldt-Jakob disease and is linked to eating beef from infected cattle.
Tom Shanahan, a spokesman for the Idaho Department of Health and Welfare, said five of the cases involve people who have already died, lived in neighboring counties and were over the age of 60. The sixth case centered on a man, also over the age of 60, who lived 90 miles away and was still alive.
“It is the naturally occurring type of CJD,” Shanahan said. “It is not variant.”
Naturally occurring CJD is found at a rate of about one case per 1 million population annually, according to the U.S. Centers for Disease Control. Yet in a state with only 1.4 million people the fact that Idaho has so many suspected cases of the rare disease has sparked concern.
Creutzfeldt-Jakob disease Definition
Creutzfeldt-Jakob disease is a disorder involving rapid decrease of mental function and movement. These are abnormalities believed to be caused by damage done to the brain by a protein called a prion. This protein folds abnormally, and seems to encourage other proteins to become similarly misshapen, affecting their ability to function.
Shanahan said researchers at Case Western Reserve confirmed that brain tissue from one woman showed CJD caused her death and that the state was waiting for results from two other tests. All the deaths occurred this year, beginning in February, he said.
“We actually are real concerned because we have never had more than three cases in a year and they are in one geographic area,” Shanahan said.
The sixth suspected case involves an elderly man who has not yet died, he said. The disease cannot be confirmed until a brain sample is collected and analyzed after death.
Investigators so far have not been able to pinpoint anything that may have caused the disease and are looking at such factors as the victims’ diets.
The Centers for Disease Control in Atlanta is monitoring the Idaho situation but has not been asked by the state to participate in a formal probe, said agency spokesman David Daigle.
The U.S. meat industry also said the outbreak of cases had no connection to mad cow disease or bovine spongiform encephalopathy (BSE) and reassured consumers that meat was safe to eat.
“We are confident in the accuracy of the assessment of the Idaho Health Department that these cases of CJD have absolutely nothing to do with BSE,” said American Meat Institute President J. Patrick Boyle. “Beef has been, and remains, safe to eat,”
Creutzfeldt-Jakob disease Causes, incidence, and risk factors
Creutzfeldt-Jakob disease can occur sporadically (for no known reason), as a result of exposure to contaminated products. Rarely, it can be genetically inherited. The disorder itself is rare, occurring in about 1 out of 1 million people. It usually first appears in midlife, beginning between ages 20 and 70, with average age at onset of symptoms in the late 50s.
However, some cases have occurred in adolescents who have received growth hormone derived from the pituitary glands of cadavers (dead bodies). Prions cannot be destroyed by ordinary disinfection techniques used to prevent transmission of viruses and bacteria. As a result, the hormone remains contaminated, and this exposure is believed to be responsible for the early onset of the disease in these people.
Cadaver-derived growth hormone has been replaced by synthetically manufactured growth hormone, so this source of contagion is no longer a problem. Other cases have occurred when people were given corneal transplants from infected donors, and from contaminated electrodes that were used in brain surgery (before it was known how to properly disinfect instruments).
More recently, a type of disease called new variant Creutzfeldt-Jakob disease has emerged. It was first reported in the U.K. in people who had eaten meat from cows who were fed infected bone meal.
For more information check Creutzfeldt-Jakob disease
In recent years, the United States has reported fewer than 300 cases of CJD each year, according to the Centers for Disease Control
Last year, health officials found a cluster of 13 deaths due to naturally occurring CJD in New Jersey between 1988 and 1992. All of those people either attended or worked at a racetrack in Cherry Hill, New Jersey, according to investigators.
The variant form of CJD is the human equivalent of bovine spongiform encephalopathy, or mad cow disease, and is contracted by people who eat beef from infected cattle.
CJD Symptoms
- Personality changes
- Hallucinations
- Muscle twitching
- Muscle stiffness
- Nervous, jumpy feelings
- Changes in gait (walking, locomotion)
- Lack of coordination - stumbling, falls
- Speech impairment
- Poor enunciation (hard-to-understand speech or mumbling)
- Sleepiness
- Delirium or dementia develops rapidly o Deterioration in all aspects of brain function o Profound confusion, disorientation
The naturally occurring strain of CJD has no known cause.
However, both types are incurable diseases involving a malformed protein, or prion, that kills brain cells.
The United States has confirmed two cases of mad cow disease, one in a Washington state dairy animal in 2003 and the other in a Texas beef cow, this year.
Revision date: July 7, 2011
Last revised: by Dave R. Roger, M.D.