PROPHYLACTIC VACCINATION 287 



sequently cultures are made to determine the sterility of the vaccine. 

 Standardization is usually on the basis of 1000 million organisms per 

 cubic centimeter. If it be desired to give a smaller number of organisms, 

 fractions of a cubic centimeter may be employed. It is the practice in 

 commercial houses to place specified doses in small ampoules so that 

 the physician may administer for each dose the contents of a single 

 ampoule. In military practice the vaccine is placed in small bottles with 

 a rubber cap so that a needle may be thrust through the cap and the 

 required amount of vaccine withdrawn into a syringe. 



As the paratyphoid fevers have been studied, it has been considered 

 advisable to vaccinate against these at the same time as against typhoid 

 fever. Therefore, vaccines are now prepared containing the bacillus 

 typhosus, bacillus paratyphosus A and bacillus paratyphosus B. It has 

 been customary to introduce smaller quantities of the paratyphoid 

 bacilli so as not to increase to an unfavorable degree the bulk of for- 

 eign protein injected. Accordingly for each 1000 million typhoid bacilli 

 there are usually added 500 million each of paratyphoid A and B. The 

 actual numbers, however, vary in different countries. Castellani rec- 

 ommends the addition also of cholera vibrios. This transforms the 

 triple vaccine into a tetra vaccine. In northern latitudes this is not of 

 particular importance. 



As has been indicated, the organisms are usually suspended in salt 

 solution, but recently neutral oil, such as commercial cottonseed oil, 

 has been employed for suspension. For such suspension the organisms 

 must be very carefully dried before being emulsified in the oil. These 

 lipovaccines have the advantage of being administered in one dose and 

 of producing little or no reaction. They produce immunity following 

 a single injection because of the slow absorption of the oil and its 

 contained antigen. 



Method of Administration. In the case of the lipovaccines a single 

 large dose of organisms may be administered. The use of the salt 

 solution suspensions involves several injections. As a rule, the first 

 dose contains 500 million typhoid bacilli and 250 million each of para- 

 typhosus A and B. The second and third doses contain 1000 million 

 typhoid bacilli and 500 million each of the paratyphoid bacilli. The 

 time between injections has been the subject of considerable study, but, 

 as a rule, a period of seven to ten days intervenes between these injec- 

 tions. Subcutaneous administration is practically universal. Intra- 

 venous injections have been recommended, but this method is not widely 

 practiced. Lumiere and Chevrotier have administered by mouth gela- 

 tine-coated pills of a dried mixed polyvalent typhoid colon vaccine. It 

 is probable that this method is not effectual, since the bacterial protein 

 must undergo at least partial digestion in the intestinal tract. Bes- 

 redka, however, has recently demonstrated in animals the possibility 

 of successful vaccination through the intestinal tract, but his animals 

 had previously been given bile, and it seems likely that this substance 

 produced sufficient lesion of the intestinal mucosa to permit of 

 direct absorption. 



