Recent Additions to Knowledge of Poliomyelitis

During the past two years, several hundred articles dealing with many phases of the study of infantile paralysis have appeared in the medical press. While not all of the significant contributions that have been published during this period are considered, aspects to be covered are etiology, pathogenesis, factors precipitating paralysis in experimental animals and man, immunization studies, and finally, the very important discovery that the virus can be grown in cultures of non-nervous tissue. ETIOLOGY Cross immunity tests have shown that the poliomyelitis viruses can be separated into three broad antigenic groups. This investigation, involving several hundred strains of the virus, has been completed, and a report of the results of the first 100 strains typed has already been published. The program, guided by the special Committee on Typing of the National Foundation for Infantile Paralysis, was carried out by four teams of investigators located at the universities of Pittsburgh,