Based on the analysis of morbidity and population's immunity status in the North, a conclusion has been drawn that changes in the immunological reactivity of the organism due to autosensitization form the basis for chronization of pathological processes in the Far North. The discussion of the problem is supported by the correlation of the findings with the material characterizing the infections developed in sensitization of the organism with other antigens (as exemplified by opisthorchiasis invasion). A hypothesis is made that chronic population stresses and mass-scale allergization of the population are causes of the recent global trend toward formation of chronic pathology.