116 THE ACUTE SELF-LIMITED INFECTIONS 



sanitary improvements, and should be urged whenever the 

 typhoid rate is high. 



By the use of this prophylactic, typhoid fever has prac- 

 tically disappeared from the United States Army. 



Vaccines have also been used during an attack of typhoid, 

 but the results, while satisfactory to some observers, cannot 

 be said to be generally acceptable. 



Paratyphoid Fever. There is a variety of enteric fever 

 called paratyphoid fever. This is caused by the Bacillus 

 paratyphosus, an organism closely allied to the true typhoid 

 bacillus and only separated from it by its ability to ferment 

 certain sugars and the quantity of acid it produces under 

 artificial conditions. In paratyphoid fever, however, the 

 blood will not clump (agglutinate) the true typhoid bacillus, 

 but does have such an action upon the paratyphoid bacillus. 

 In this form of fever the course is shorter, the attack is 

 milder, and complications are much less frequent. There is 

 usually no ulceration of Peyer's plaques and therefore hemor- 

 rhage from the bowel is of extreme rarity. It is nevertheless 

 an infectious disease, entirely comparable in its origin, course, 

 transmission, and epidemic character to true typhoid fever, 

 and the same precautions of disinfection must be observed. 

 Paratyphoid infections are due to two closely related sub- 

 varieties; they occur at times in epidemics like typhoid; 

 they are amenable to the same prophylactic measures. 



It is now the practice to give a single vaccine with all three 

 organisms in it, typhoid and paratyphoid A and B bacilli; 

 this protects against all these infections. This " triple vac- 

 cine" is now given in three doses ten days apart, but it is 

 expected that this procedure will be shortly superseded by a 

 single dose of the required number of germs suspended in oil, 

 a medium which holds the organisms in good suspension and 

 permits a slow absorption conducive to a thorough immuni- 

 zation. All typhoid and paratyphoid infections have been 

 practically eradicated in the armies at war. 



