The question of clustering of Creutzfeldt-Jakob disease.

Clustering of Creutzfeldt-Jakob disease has been reported in several countries. The authors review these reports, and they describe their statistical analysis of clustering among 329 cases that died in France during 1968-1982. Paris was found to have a much higher case rate than the rest of France, while some large areas in the north and west had remarkably few cases relative to their populations. No rural clusters were identified. A number of explanations for regional variations in case rates are possible, including population characteristics and case finding artifacts. Based on their results and those of other studies, the authors conclude that the strongest evidence for clustering of Creutzfeldt-Jakob disease is familial and ethnic, rather than geographic.