64 BACTERIOLOGY. 



typhoid vaccination is being largely practised. In the 

 Massachusetts General Hospital 1381 nurses and 

 attendants were vaccinated with no cases of typhoid 

 developing subsequently. 



The injections are usually made in the arm, and 

 are followed rarely by a reaction marked by fever, 

 headache, and malaise. This occurs in only i per 

 cent, of the cases. 



THE BACILLUS PARATYPHOSUS. 



The paratyphoid bacillus in shape and size is very 

 much like the typhoid bacillus. It is differentiated 

 from the typhoid bacillus by its ability to ferment 

 glucose. There are two types of paratyphoid bacilli, 

 called type A and B, which differ slightly in their 

 method of growth. They also behave differently in 

 the agglutination or Widal reaction. The blood of 

 patients sick with paratyphoid fever will not agglu- 

 tinate the typhoid bacillus. If the infection is due to 

 paratyphoid A the blood will not agglutinate the 

 paratyphoid B, but only the A. 



The agglutination reactio-n is a very good way to 

 diagnose the type of infection present in all cases of 

 typhoid-like infection. 



The course of the fever in paratyphoid infections 

 is somewhat milder and shorter than in typhoid. In 

 the fatal cases coming to autopsy the spleen and 

 mesenteric glands are enlarged just as in typhoid, but 

 the intestines show little change. Changes in the 



