ATLANTA—Three Wisconsin men who died of degenerative neurologic illnesses after participating in wild game feasts were not the victims of the prion infection that is causing an epidemic of chronic wasting disease in the deer and elk in Colorado, Wyoming, Wisconsin, Kansas, Minnesota, Montana, Nebraska, Oklahoma, and South Dakota, according to a report in the February 21 Morbidity and Mortality Weekly Report. However, the Centers for Disease Control and Prevention (CDC) has asked neurologists in these areas to maintain a high index of suspicion for Creutzfeldt-Jakob disease and to promptly report all possible cases.

Hunters and wild venison consumers were advised to follow special precautions to prevent potential exposure to the prion that causes chronic wasting disease in deer and elk. Although that pathogen is thought to be unable to infect humans, the situation is being monitored closely by the CDC and by the agriculture and wild game departments of the states involved.

LAST MEAL?

Medical epidemiologist Vincent Hsu, MD, MPH, told Neurology Reviews that the three Wisconsin deaths first came to the attention of the CDC following reports in a Milwaukee newspaper. According to Dr. Hsu, who investigated these cases as part of the CDC’s Epidemiologic Intelligence Service, the family of one patient notified local media after they learned that two other men from the same group of outdoorsmen had contracted similar neurologic wasting diseases. All were part of an informal club that often gathered at a cabin in northern Wisconsin to share meals of wild game. All three patients investigated by the CDC had progressive symptoms such as seizures, dementia, tremors, ataxia, speech abnormalities, myoclonic jerking, personality changes, decreased reflexes, and EEG abnormalities.

The first patient, a lifelong hunter, had frequently eaten venison and had hosted the wild game feasts at his cabin. Creutzfeldt-Jakob disease was suspected in this case, and neuropathologic examination of brain tissue at autopsy revealed a subacute spongiform encephalopathy compatible with that diagnosis. However, subsequent examination of brain tissue by the National Prion Disease Pathology Surveillance Center (NPDPSC) found no evidence of prion-related disease.

The second patient was not a hunter but had a history of eating venison and had participated in one of the wild game feasts. Neuropathologic evaluation of brain tissue at autopsy documented widespread subcortical spongiform lesions characteristic of Creutzfeldt-Jakob disease. Subsequent examination of sections of brain tissue at the NPDPSC confirmed prion disease but showed that it was the most common form of sporadic Creutzfeldt-Jakob disease, not an unusual form such as might have been expected if the disease had been contracted from deer or elk suffering from chronic wasting disease.

The third patient had symmetrical frontal lobe cerebral cortical atrophy and mild temporal lobe atrophy at autopsy but no spongiform lesions. Examination of brain tissue by the NPDPSC showed no lesions indicative of Creutzfeldt-Jakob disease and no evidence of prion diseases.

“There was only one confirmed case of Creutzfeldt-Jakob disease among these three suspected cases, and that patient had fairly ordinary sporadic Creutzfeldt-Jakob disease, not the kind of prion that has been seen in animals with the chronic wasting disease,” Dr. Hsu said.

A SERIOUS CONCERN

In light of the spread of bovine spongiform encephalopathy from animals to humans in Britain, the possibility that chronic wasting disease might spread from deer or elk to humans remains a serious concern for the CDC and state health departments. Dr. Hsu urged clinicians who see any cases of possible Creutzfeldt-Jakob disease to try to achieve a definitive diagnosis.

“There is no cure for Creutzfeldt-Jakob disease, so this will not do much to help the patient, but it will help epidemiologists who are studying these problems,” Dr. Hsu said. He also pointed out that recent work showing that prion protein is detectable in samples of olfactory mucosa from patients with Creutzfeldt-Jakob disease suggests that such mucosal biopsies might permit definitive early diagnosis and provide a way to monitor the efficacy of antiprion compounds now in development.

Guidelines for Hunters

Fatal chronic wasting disease continues to spread among wild deer and elk herds in an ever-widening region. Most affected states have initiated monitoring programs for wild and for farm-raised deer and elk. Hunters have been advised not to eat the eyes, brain, spinal cord, spleen, tonsils, or lymph nodes of any deer and not to eat any part of a deer that appears sick. The recommended procedure is to gut the deer, remove the head, cut meat from the bone with a knife without cutting through bones, and remove all fat, membranes, and cords from the meat. Hunters also should wear rubber or latex gloves when field-dressing animals, minimize contact with the brain, spinal cord, spleen, and lymph nodes, not use household knives or utensils for field dressing, and clean all knives and equipment with a 50/50 solution of chlorine bleach and water.

Physicians suspecting possible Creutzfeldt-Jakob disease in patients are asked to contact the NPDPSC at (216) 368-0587 or www.cjdsurveillance.com. Instructions for safe cutting and processing of deer and elk can be found on the Wisconsin Department of Agriculture Web site at http://datcp.state.wi.us/ah/agriculture/animals/disease/chronic/

NR

—Janis Kelly

Suggested Reading
Centers for Disease Control and Prevention. Fatal degenerative neurologic illnesses in men who participated in wild game feasts—Wisconsin, 2002. MMWR Morb Mortal Wkly Rep. 2003;52:125-127.
Zanusso G, Ferrari S, Cardone F, et al. Detection of pathologic prion protein in the olfactory epithelium in sporadic Creutzfeldt-Jakob disease. N Engl J Med. 2003;348:711-719.

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