PARA-TYPHOID FEVER 375 



The para-typhoid bacilli are morphologically like the 

 typhoid bacillus and are actively motile, but they ferment 

 glucose with the production both of acid and of gas. A 

 number of races have been isolated differing from one 

 another in their source, rate of fermentation of glucose, 

 action on milk, action on neutral red, and agglutination 

 reaction, and are distinguished by the names of those who 

 isolated them. 



Two groups of para- typhoid bacilli may be distinguished 

 which have been termed A and B by Buxton. Group A 

 produces less gas in glucose media than group B ; with 

 group A milk remains permanently acid ; with group B 

 it becomes alkaline after a transient acidity ; and though 

 group A changes neutral red to yellow, the red colour tends 

 to return after three weeks or so, while with group B the 

 yellow colour is permanent. That is to say, in its reactions 

 group A is more closely allied to the typhoid bacillus than 

 is group B. 



B. para-typhosus A or a is rarely found, the vast majority 

 of cases of para-typhoid fever being associated with the 

 presence of the B or p type. The fermentation reactions 

 of some of the para-typhoid bacilli are given in the Table 

 on p. 381. 



As regards the agglutination reaction, the blood of the 

 para-typhoid fever patient either does not agglutinate 

 the typhoid bacillus or agglutinates it only in low dilution 

 e.g. 1 in 10 to 40, while it agglutinates the para-typhoid 

 bacilli in far higher dilution e.g. I in 100 or 200, or even 

 higher ; thus in Cushing's case the patient's serum agglu- 

 tinated the para-typhoid bacillus isolated from it up to 

 1 in 8000. 



The diagnosis of para-typhoid fever would be based 

 on (a) the agglutination reaction ; (6) the isolation of a 

 para-typhoid bacillus by cultures from the blood (p. 369). 

 Prophylactic vaccines for para-typhoid fever may be 



