PROPHYLACTIC VACCINATION 



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doned because of the possibility of transferring infection in the crusts, 

 not the least important of which is syphilis. With the development of 

 important Board of Health laboratories and large commercial lab- 

 oratories it is now possible to secure cowpox virus in a form free 

 from infective organisms. 



DEATH-RATE FROM SMALLPOX, AVERAGE PER 1,000,000 INHABITANTS. 



The Preparation of Smallpox Vaccine. For this purpose cow- 

 pox is produced in young heifers from two to four months old. The 

 animals are taken from selected stock, carefully tested for the presence 

 of tuberculosis and observed for several days so as to< ensure perfect 

 health. The body is cleansed and the abdominal surface shaved from 

 the ensiform cartilage to the pubis, extending the area out on the 

 flanks and the inner surface of the thighs. The skin is washed with 

 soap and water, then with alcohol and finally with sterile water. About 

 100 small cuts through the epidermis are made under strictly aseptic 

 precautions. If bleeding occurs the blood is carefully wiped away. 

 Virus may be obtained primarily from smallpox patients who are 

 otherwise healthy. At the present time, however, the virus kept as 

 " seed virus " is obtained from previously inoculated animals. Virus 

 is introduced into the scarifications usually in the form of a glycerol 

 suspension. In about forty-eight hours a reaction appears and by the 

 sixth day the vesicles are well filled with semipurulent material. The 

 animal is killed and the vesicles carefully curetted away. After the 

 curettage, serum appears and this may be preserved in ampoules or 

 small tubes for subsequent vaccination. The pulpy mass obtained 

 by curettage is mixed with four times its weight of a mixture com- 

 posed of glycerol 50 per cent., water 49 per cent., phenol i per cent. 

 The glycerolated pulp is allowed to stand three or four weeks in order 

 to destroy any contaminating bacteria. The pulp is then triturated in 



