I9I3.] TYPHOID FEVER BY VACCINATION. 229 



Polyvalent Vaccine. 



At the present time many laboratories are using what is called 

 polyvalent vaccine; that is, one made of a number of pure cultures 

 derived from different sources, mixed together in approximately 

 equal proportions. Thus, in preparing vaccine for the immuniza- 

 tion of the French soldiers in Morocco cultures were obtained from 

 cases of typhoid fever occurring in that country. Some bacteriolo- 

 gists also add to the vaccine cultures of the para-typhoids, A and B. 

 At the Laboratory of Hygiene of the University of Wisconsin it is 

 our invariable practice to prepare polyvalent vaccine. 



Vincent, who has prepared most of the vaccine used in the French 

 army, uses twelve different strains. After full growth has been ob- 

 tained, the bacteria are autolized in salt solution with frequent shak- 

 ing, and killed by being subjected to the action of sulphuric ether. 



Dosage. 



In America the dose universally employed is that advised by the 

 army. Three doses are given ten days apart. The first dose con- 

 sists of five hundred million bacteria, the second and third one thou- 

 sand million each. The injections are made preferably in the upper 

 arm about the insertion of the deltoid muscle, and are given under 

 the skin and not into the muscles. The skin is sterilized with iodine, 

 and the sterile needle is thrust through the area thus prepared. It 

 is customary to vaccinate about four o'clock in the afternoon so that 

 any reaction which takes place will occur during the night and be 

 practically over with by the next day. 



The use of alcohol in any form is prohibited, as even moderate 

 amounts seem to increase the severity of both local and general 

 symptoms. 



No special precautions are necessary and the vaccine does not 

 usually interfere with the ordinary vocations of life. Occasionally 

 slight chilliness and even rigors may occur combined with headache, 

 general malaise, and sometimes distinct nausea. Locally, there is 

 an area of redness and tenderness, the worst of which is over with 

 within twenty-four hours. Suppuration never occurs. 



The vaccine is well borne bv women and children, but the dose 



