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(2) Creutzfeldt-Jakob disease developed after inoculation into hamsters of the brain biopsy material from our patient. (3) Creutzfeldt-Jakob disease is very rare in man, with an incidence of 1 per million per year." It may be that, in fact, a higher proportion of the population is infected, as with diseases caused by conventional viruses (e.g., poliomyelitis), without any or with only trivial or subclinical signs. In the absence of any serological tests in transmissible dementias, animal transmission experiments may be useful in checking this

hypothesis. supported by

U.S. Public Health Service grant

Departments of Pathology, Neurology, and Neurosurgery, Yale University School of Medicine,

ELIAS E. MANUELIDIS LAURA MANUELIDIS JONATHAN H. PINCUS WILLIAM F. COLLINS

*

This

study

was

M