[Creutzfeldt-Jakob disease in the squirrel monkeys]

Four different strains of Creutzfeldt-Jakob disease virus (2 primary and 2 passaged in primates or mice) were inoculated intra-cerebrally into squirrel monkeys implanted with continuously-recording indwelling electrodes. Simultaneous EEC and videotape recordings were made on unrestrained animals. In addition EEG recordings were made of evoked visual potentials on restrained animals. EEG abnormalities appeared in every animal before the first clinical signs (6 to 20 months after inoculation) and included generalized slowing, epileptiform patterns and occasional episodes of pseudo-periodic activity. Abnormal evoked visual potentials and disturbances of consciousness were also noted. All viral strains produced similar disorders and the death of inoculated animals. The relative frequency of epilepsy seen in the CJD-inoculated squirrel monkey contrasts with its irregular occurrence in most other monkey species, and its total absence in the spider monkey. This could be related to the lesser complexity of neo-cortical evolution in the squirrel monkey and a less pronounced development of inhibitory CNS mechanisms under the general control of GABA-ergic neurons.