I9I3.] TYPHOID FEVE:R by VACCINATION. 227 



shown that this amount of heat injures or destroys to a great extent 

 the power of the germs to produce a good response in the formation 

 of those substances on which the body depends for its protection. 

 At the present time the cuhures are killed by heating to 53° C. 



It was tried next on a large scale in the German Colonial army 

 during the Hereros campaign of 1904-07. The reports of this ex- 

 pedition show that the percentage of typhoid fever among the unin- 

 oculated was almost 10 per cent., whereas among the vaccinated it 

 was only a trifle over 5 per cent. Further than this, the figures show 

 that 76.01 per cent, of the inoculated who contracted the disease had 

 mild or moderately severe cases, with the fatal cases numbering 6.47 

 per cent., whereas only 61 per cent, of the uninoculated had light or 

 moderately severe cases, while the mortality reached 12.80 per cent. 

 It was further shown that among the vaccinated 60 per cent, of the 

 fatal cases occurred in those who had received only one dose of vac- 

 cine, 33 per cent, in those who had received two doses, and only 8^ 

 per cent, in men who had received the three inoculations (Russell). 



The value of the method has been made the subject of study by 

 a number of commissions appointed by various governments all of 

 which have made favorable reports. After careful consideration, 

 anti-typhoid vaccine was introduced in the United States army as a 

 voluntary measure in 1909. The favorable results were so striking 

 that in 191 1 it was made compulsory for all officers and enlisted 

 men under the age of forty-five years. The most striking example 

 of its efficacy is afforded by a comparative study of two bodies of 

 soldiers, approximately equal in numbers, living under similar con- 

 ditions during the same period of the year, and in much the same 

 climate, one stationed at Jacksonville, Fla., in 1898; the other at 

 San Antonio, Tex., during the maneuvers of 191 1. At Jacksonville 

 there were 10,759 men, with 2,693 cases of illness known, or believed 

 to be, typhoid fever, and 248 deaths. At San Antonio there were 

 12,801 soldiers with only one case of typhoid fever, which resulted 

 in recovery. During the same time there occurred in the city of 

 San Antonio forty-nine cases of typhoid fever with nineteen deaths, 

 showing that the infection was prevalent in that community and 

 demonstrating that the difference in the incidence of typhoid fever 



PROC. AMER. PHIL. SOC, Ul . 209 O, PRINTED JUNE 7, I9I3. 



