Studies on Varicella. the Susceptibility O~f Rabbits to Tiie Virus of Varicella

In spite of the ignorance regarding the etiological agents concerned in the contagious diseases of children, it has been possible, through the careful clinical observations of such men as Sydenham, to differentiate one from the other. Notwithstanding this wide clinical knowledge, it is still impossible to control the spread of these diseases, or to arrest their course once they have established themselves in susceptible individuals. It is true that some progress has been made in the prevention of measles, scarlet fever, and chicken-pox by the introduction of the method of injecting serum from convalescent patients into exposed individuals. Attempts have also been made to prevent chicken-pox by vaccination with fresh vesicle lymph, and while a few workers have reported positive results with this method, the majority of investigators have not succeeded. It is evident that these procedures involve objectionable features which would detract from the usefulness of the methods were an attempt made to apply them widely. To develop better methods of prevention, it is highly desirable to transmit the diseases to animals in such a way as to obtain a concentrated virus similar to vaccine virus or the virus of rabies. Varicella is usually considered a mild disorder, but, nevertheless, for many reasons, it has appeared to be a suitable one on which to begin study.