D. C. Gajdusek

The epidemiology of Creutzfeldt‐Jakob disease Conclusion of a 15‐year investigation in France and review of the world literature

During the 15-year period 1968–1982, a total of 329 patients dying of Creutzfeldt-Jakob disease (CJD) were identified in continental France. Annual mortality rates stabilized at 0.5 to 0.6 cases per million (1.1 to 1.2 cases per million in Paris). Six percent of cases were familial. Although the frequency of CJD was related to population density, no contacts could be established among the great majority of patients. No association with socioeconomic factors, preceding trauma or surgery (excepting one iatrogenic neurosurgical case), or exposure to animal sources of infection was identified. Evidence from this and other epidemiologic studies suggests that CJD is a minimally contagious disease that may be principally acquired in early life from presymptomatic patients, asymptomatic carriers, or chance contamination by environmental sources. It is possible that CJD could also occur sporadically as a noncontagious disease by a mechanism akin to oncogenes in carcinogenesis.

Disappearance of high-incidence amyotrophic lateral sclerosis and parkinsonism-dementia on Guam.

The high incidence rates of amyotrophic lateral sclerosis (ALS) and parkinsonism-dementia (PD) occurring among the Chamorros of Guam have declined to rates only slightly higher than those observed in the continental United States. This decline has occurred principally among males, especially those born after 1920 and living in areas where calcium and magnesium levels are low in soil and water. The male-to-female ratio among affected patients now approaches unity, compared with ratios of 2 to 1 for ALS and 3 to 1 for PD three decades ago. These changes are consistent with the hypothesis that the previously high incidence resulted from defects in mineral metabolism and secondary hyperparathyroidism, provoked by nutritional deficiencies of calcium and magnesium, with resultant deposition of calcium and aluminum in neurons.

Survival of scrapie virus after 3 years' interment

Supernatant fluid from a scrapie-infected hamster brain homogenate was mixed with soil, packed into perforated petri dishes that were then embedded within soil-containing pots, and buried in a garden for 3 years. Between 2 and 3 log units of the input infectivity of nearly 5 log units survived this exposure, with little leaching of virus into deeper soil layers. These results have implications for environmental contamination by scrapie and by similar agents, including those of bovine spongiform encephalopathy and Creutzfeldt-Jakob disease.

Iatrogenic Creutzfeldt‐Jakob disease: An example of the interplay between ancient genes and modern medicine

We tested DNA from 15 centrally infected cases of iatrogenic Creutzfeldt-Jakob disease (CJD) (dura mater or corneal homografts and stereotactic EEG electrodes), 11 peripherally infected cases (native human growth hormone or gonadotrophin), and 110 control individuals for the presence of mutations in the chromosome 20 amyloid gene. No patient or control had any of the known pathogenic point or insert mutations found in familial disease, but allelic homozygosity at polymorphic codon 129 was present in all but two (92%) of the 26 patients, compared with 54 (50%) of the 110 controls (p < 0.001). Pooled data from all identified and tested cases of iatrogenic disease yielded a worldwide total of 56 patients, of whom all but four were homozygous at codon 129 (p < 0.001). These findings support the thesis that homozygosity at codon 129 enhances susceptibility to iatrogenic infections of both central and peripheral origin, with evident implications for the population of dura mater homograft and pituitary hormone recipients whose lives have been complicated by the possibility of exposure to the infectious agent of CJD.

Evidence for and against the transmissibility of Alzheimer disease

Nonhuman primates were inoculated intracerebrally with brain tissue from 52 patients with confirmed Alzheimer disease (AD) in order to investigate the possibility of an infectious etiology. Animals inoculated with brain tissue from two patients with familial AD developed a spongiform encephalopathy that was indistinguishable from Creutzfeldt-Jakob disease (CJD). Seventeen other cases of AD on test for more than 50 months failed to produce similar changes, and 33 cases have not been incubating for a sufficient period of time to ascertain the presence of a transmissible agent. The initial transmission of spongiform encephalopathy with brain tissue from the two familial cases of AD has not been reproduced and the association between AD and an infectious agent has not yet been demonstrated with any reasonable degree of certainty. The frequent overlap of clinical symptoms of AD and CJD, and the occurrence of cases of CJD and AD in the same families indicate the need for continuing research on the relationship between the two diseases.

A simple and effective method for inactivating virus infectivity in formalin-fixed tissue samples from patients with Creutzfeldt-Jakob disease

We fixed brains from hamsters infected with scrapie virus in (1) formalin, (2) phenol-saturated formalin, (3) formalin with a 1-hour immersion in formic acid, or (4) phenol-saturated formalin with a 1-hour immersion in formic acid. In addition, we used the formalin-formic acid procedure on brains from mice infected with the virus of Creutzfeldt-Jakob disease. Formic acid proved superior to phenol in respect to both disinfection and tissue preservation, almost completely eliminating virus infectivity in sections that were histologically indistinguishable from formalin-fixed material. The inclusion of a formic acid step in routine formaldehyde tissue fixation will thus provide histologic sections of excellent quality, and virtually eliminate the risk of handling infectious material in the subsequent neuropathologic processing of tissues from patients with CJD.

Amyotrophic lateral sclerosis and parkinsonism‐dementia on Guam A 30‐year evaluation of clinical and neuropathologic trends

We reviewed the records of 279 Guamanian Chamorro patients with amyotrophic lateral sclerosis (ALS) and 293 patients with parkinsonism-dementia (PD), who had onset of symptoms between 1950 and 1979, to determine if there were changes in the clinical and neuropathologic features that might clarify the declining incidence rates in the past decade. There were no major temporal changes in the frequencies of physical findings or histopathologic features, but in the past three decades, an increase in age at onset was observed for both ALS and PD. There was also a shorter duration of illness in ALS and a longer duration in PD. Good correlation was found between the clinical and pathologic findings for both ALS and PD throughout this period.

Low-calcium, high-aluminum diet-induced motor neuron pathology in cynomolgus monkeys

SummaryLong-term epidemiological studies indicate that environmental factors play a causative role in high-incidence amyotrophic lateral sclerosis (ALS) and parkinsonism-dementia (PD) in the western Pacific. An increased risk for disease is acquired in youth and remains for life. The low concentrations of calcium and magnesium and high levels of aluminum in the soil and drinking water, along with the relative isolation of these populations, constitute an unusual environmental feature common to all three high-incidence foci. Studies of mineral deposition in brain tissue of Guamanian ALS and PD patients, as well as of neurologically normal Guamanians with neurofibrillary degeneration, demonstrate accumulations of calcium, aluminum and silicon in neurofibrillary tangle-bearing neurons. In an attempt to duplicate the low calcium and high aluminum and manganese in soil and drinking water in these foci, we maintained juvenile cynomolgus monkeys for 41 to 46 months on a low-calcium diet with or without supplemental aluminum and manganese. Experimental animals exhibited mild calcium and aluminum deposition and degenerative changes, compatible with those of early ALS and PD, in motor neurons of the spinal cord, brain stem, substantia nigra and cerebrum. Neuropathological findings included chromatolysis, aberrant perikaryal accumulation of phosphorylated neurofilament, neurofibrillary tangles, axonal spheroids, and basophilic and hyaline-like inclusions consisting of abnormal cytoskeletal elements by electron microscopy. The magnitude and extent of these lesions far exceeded those found in normal aged monkeys.

Clinical and molecular genetic study of a large German kindred with Gerstmann‐Straussler‐Scheinker syndrome

We have verified, by full open reading frame sequencing, the presence of an amino-acid-altering mutation in codon 102 of the scrapie amyloid protein gene in three affected members of a large and well-documented German family with experimentally transmitted Gerstmann-Straussler-Scheinker syndrome. In addition, we identified the mutation by partial sequencing or DNA restriction enzyme analysis in three of 12 presently healthy family members with an affected parent, and none of 12 members without an affected parent. Thus, a total of six of 15 family members at risk for the disease (including the three established cases) had the same codon 102 mutation, a proportion consistent with the autosomal dominant inheritance pattern of disease expression. It is undetermined whether the mutation influences susceptibility to infection by an exogenous agent or is itself a proximate cause of disease.

An insert mutation in the chromosome 20 amyloid precursor gene in a Gerstmann-Sträussler-Scheinker family

We report the finding of an insert mutation in the chromosome 20 amyloid precursor gene in a family with neuropathologically-verified, experimentally-transmitted Gerstmann-Sträussler-Scheinker syndrome (GSS). The insert consisted of 8 extra copies of a repeating octapeptide coding sequence in the region between codons 51 and 91; it was identified in the proband and a presently unaffected at-risk niece by full sequencing of the open reading frame, and was visualized electrophoretically in the proband and 6 of 12 at-risk relatives. Although affected members in this French-Breton family have shown a variety of clinical profiles, including durations of illness that ranged from 3 months to 13 years, all autopsied cases (including the patient with the shortest illness) have had the distinctive multicentric amyloid plaques that define GSS as a nosologic entity.