[Seasonal differences in the pathomorphological reactions of monkeys to poliomyelitis vaccine]

Weak pathomorphological reactions in a group of animals are assessed by 3 scores of severity which depend on the total number of animals in the group, number of animals with pathomorphological reactions, number of body areas involved in these reactions, and the intensity of reaction expressed by crosses. Conditionally, these scores of severity characterize virulence, pathogenicity, and local pathogenicity of virus. All the 3 scores of severity for the 3 virus types were found to be highest in the winter-spring period (average for 18 years).