452 INFECTION AND IMMUNITY. 



not all cells, being killed during one hour at 

 this temperature. This may explain the fact that 

 the virus is not always killed by cooking the meat. 

 The organism probably has a wide distribution 

 because of the occurrence of the infection in vari- 

 ous parts of the world. 



The toxicity of the bacilli depends on the exist- 

 ence of a fixed endotoxin; a soluble toxin is not 

 produced. The principles of prophylaxis against 

 typhoid also apply to paratyphoid fever, with the 

 addition that in the latter disease the possibility of 

 meat infection must be kept in mind. 



The serums of patients and immunized animals 

 acquire bactericidal, opsonic and agglutinating 

 powers for the organism. There is no serum ther- 

 apy for the infection, nor has the occasion arisen 

 to attempt vaccination. 



Serum from a paratyphoid patient may aggluti- 

 l Biood nate the homologous bacillus in a dilution of 

 cultures, j/iooo or 1/2000 or more (E. H. Buediger), 

 whereas the typhoid bacillus is agglutinated only 

 in low dilutions by the same serum. How- 

 ever, bacillus A and bacillus B are not identical 

 in their agglutinable properties; in this respect 

 it is stated that the latter is more closely re- 

 lated to the typhoid bacillus than the former. 

 The agglutination test 1"s said to have a higher 

 diagnostic value than the Gruber-Widal reaction 

 in typhoid, a stronger agglutinating power being 

 developed in the serum of the patient. Never- 

 theless, the formation of coagglutinins may render 

 the test confusing if proper serum dilution is not 

 practiced. Conclusions should not be attempted 

 until the test has been performed with both strains 

 of the paratyphoid bacillus and with the typhoid 



