678 ACTIVE IMMUNIZATION 



tenth day the characteristic features are more marked, and the lesion has 

 usually reached its height, being accompanied by a burning sensation 

 and an almost uncontrollable desire to scratch (Fig. 134). The areola 

 is now quite angry in appearance, and numerous minute vesicles are 

 seen on its surface. By the twelfth day the areola is smaller, the con- 

 tents become turbid and commence to dry, so that a few days later a 

 scab has formed that drops off in another week or two. 



About the fifth day the child becomes restless and irritable and shows 

 a slight elevation of temperature. These symptoms may become more 

 pronounced until the end of the second 'week, when they subside rapidly. 



Precautions should be taken to prevent scratching and infection of 

 the vesicle. The old-time " beautiful arms," with well-marked cellulitis 

 and adenitis of neighboring glands, were largely due to secondary in- 

 fection, and are not at all necessary in the process of vaccination. 

 Evidence would tend to indicate that the vesicle is the typical lesion 

 of both smallpox and vaccinia, and that the pustules are simply infected 

 vesicles. Ordinary surgical care will do much to rob vaccination of its 

 discomfort and to render the operation a most harmless one. 



The results of a vaccination, therefore, can be inspected and verified 

 on or about the seventh to the ninth day. With persons who have been 

 vaccinated successfully on a previous occasion the vaccinated area may 

 show a slight areola at the end of twenty-four hours, with or without a 

 papule, which subsides in seventy-two hours. This is called a " reac- 

 tion of immunity," and is due to the presence of antibodies against the 

 virus. Or a small, itchy, burning papule may form, which develops 

 into a small vesicle maturing on the fifth or sixth day, and then rapidly 

 subsiding, constituting the reaction known as vacdnoid (Fig. 135). 

 Occasionally vaccination is followed by the appearance of various 

 eruptions. 



The appearance of the scar varies according to its age and to the 

 degree of tissue destruction. The physician is not infrequently re- 

 quested to examine a person and determine if the scar is satisfactory 

 evidence of successful vaccination. The typical good scar is circular, 

 and about the size of a ten-cent piece, with smooth, white, and depressed 

 center and a raised border. The border shows numerous radiations, and 

 the entire scar may show little pits of former hair-follicles when the 

 lesion was sufficiently destructive to remove the upper portion of the 

 corium. (See Fig. 135.) A burn or an ordinary pyogenic infection may 

 leave scars quite similar to those of vaccination, and vaccination scars 

 may show wide variation, but the circumscribed character, the raised 

 border with radiations and depressions, and the appearance of having 



