Creutzfeldt-Jakob Disease (CJD)
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Creutzfeldt-Jakob disease is a sporadic or familial prion disease. Bovine spongiform encephalopathy (mad cow disease) is a variant form. Symptoms include dementia, myoclonus, and other CNS deficits; death occurs in 1 to 2 yr. Transmission can be prevented by taking precautions when handling infected tissues and using bleach to clean contaminated instruments. Treatment is supportive.

CJD typically affects people > 40 yr (median, about 60 yr). It occurs worldwide; incidence is higher among North African Jews. Most cases are sporadic, but 5 to 15% are familial, with autosomal dominant transmission. In the familial form, age at onset is earlier and duration of disease is longer. CJD can be transmitted iatrogenically (eg, after cadaveric corneal or dural transplants, use of stereotactic intracerebral electrodes, or use of growth hormone prepared from human pituitary glands).

vCJD is most common in the United Kingdom (UK); it develops at a younger average age (< 30 yr) than does sporadic CJD. In the early 1980s, because of relaxed regulations for processing animal by-products, tissue from sheep infected with scrapie, a prion disease, was introduced into cattle feed. Thousands of cattle developed bovine spongiform encephalopathy (BSE), called mad cow disease. Some people who ate meat from affected cattle developed vCJD.

Because the incubation period in BSE is long, a connection between BSE and contaminated feed was not recognized in the UK until BSE had become an epidemic, which was controlled by massive slaughter of cattle. In the UK, the annual number of cases of vCJD starting in 1995 peaked at 28 in 2000 and then steadily declined, with only 5 cases/yr reported between 2005 and 2007 and only 1 in 2008; as of December 2008, the total number of cases was 167. However, 2 of 3 cases linked to blood transfusion occurred in 2006. Whether there exists a latent pool of people who have received blood transfusions who are thus at risk for development of vCJD is unclear. Although vCJD has been restricted to the UK and Europe thus far, BSE has been reported in a small number of North American cattle.

Symptoms and Signs

About 70% of patients present with memory loss and confusion, which eventually occur in all patients; 15 to 20% present with incoordination and ataxia, which often develop early in the disease. Myoclonus provoked by noise or other sensory stimuli (startle myoclonus) often develops in the middle to late stages of disease. Although dementia, ataxia, and myoclonus are most characteristic, other neurologic abnormalities (eg, hallucinations, seizures, neuropathy, various movement disorders) can occur. Ocular disturbances (eg, visual field defects, diplopia, dimness or blurring of vision, visual agnosia) are common.

Prognosis

Death typically occurs after 6 to 12 mo, commonly due to pneumonia. Life expectancy in vCJD is longer (averaging 1.5 yr).

Diagnosis

MRI

Exclusion of other disorders

CJD should be considered in elderly patients with rapidly progressive dementia, especially if accompanied by myoclonus or ataxia; however, CNS vasculitis, hyperthyroidism, and bismuth intoxication must be excluded.

vCJD is considered in younger patients who have ingested processed beef in the UK; Wilson's disease should be excluded.

Diagnosis may be difficult, and diagnostic findings may develop only over time. MRI may show cerebral atrophy. Diffusion-weighted MRI frequently shows basal ganglia and cortical abnormalities. CSF is typically normal, but characteristic 14-3-3 protein is often detected. EEG may show characteristic periodic sharp waves. Brain biopsy is usually unnecessary.

Prevention

Because there is no effective treatment, prevention is essential. Workers handling fluids and tissues from patients suspected of having CJD must wear gloves and avoid mucous membrane exposure. Contaminated skin can be disinfected by 5 to 10 min of exposure to 4% Na hydroxide, followed by extensive washing with water. Steam autoclaving of materials at 132° C for 1 h or immersion in 4% Na hydroxide or 10% Na hypochlorite solution for 1 h is recommended. Standard methods of sterilization (eg, exposure to formalin) are ineffective. The US Department of Agriculture (USDA) currently carries out BSE surveillance for 2000 to 5000 cattle/mo. In 2004, a positive BSE case in the US caused testing to be expanded to an average 1000 cattle/day, but testing was subsequently reduced when ensuing years yielded only 2 positive cases.