THE PARATYPHOID GROUP 351 



medium (beta type). Isolation from the feces is made upon Endo- 

 plates in the same manner that dysentery and typhoid bacilli are 

 obtained. The final diagnosis depends upon the agglutination of the 

 bacilli with specific agglutinating sera of high potency. 1 



(b) Serological. As a routine measure the diagnosis of paratyphoid 

 fever by the agglutination test is unreliable. Not infrequently the 

 blood serum of a patient agglutinates typhoid bacilli in dilutions 

 approaching those ultimate for the homologous organism. The para- 

 typhoid bacilli and B. typhosus possess in common group agglutinins 

 which greatly vitiate the value of the test. The same objection does 

 not hold for the diagnosis of typhoid fever by the agglutination 

 reaction, however. 



The isolation of B. paratyphosus (alpha or beta) from the blood 

 stream during life, or from the internal organs at autopsy is the only 

 reliable method of diagnosis. Carriers are not uncommon, and like 

 typhoid bacillus carriers the organisms frequently remain in the 

 gall-bladder, consequently isolation of the bacilli from feces does not 

 necessarily establish a correct clinical diagnosis. Paratyphoid bacilli 

 have been isolated occasionally from gall-stones and from cases of 

 cholecystitis, particularly in women. 



SUMMARY. 



THE MORE IMPORTANT DIFFERENTIAL DETAILS OF PARATYPHOID FEVER AND 

 OF MEAT POISONING. 



Meat Poisoning. Paratyphoid Fever. 



Organism .... Hog cholera bacillus. B. paratyphosus alpha. 



B. enteritidis. B. paratyphosus beta. 



Habitat of organism . Intestinal canal of lower ani- Chiefly intestinal tract - 



mals chiefly: hog cholera of man. 

 in swine, enteriditis com- 

 mon in rodents. 



Mode of infection . . Usually contaminated meat Usually human bacilli 



(human carriers rare). carriers. 



Incubation period . . Six to forty-eight hours. Eight to twenty days. 



Symptoms .... Choleraic. Typhoidal. 



Pneumonic Infection with B. Psittacosis. B. psittacosis causes a 

 fatal enteritis in parrots, and it has been noticed, particularly in 

 France, that coincidently with enteric disease in parrots a pneumonic 

 infection has appeared in those associated with them. The disease 

 in man presents no definite clinical features which would differentiate 

 it from typhoid fever complicated by pneumonia. Tke incubation 



1 Sera that will agglutinate homologous strains in dilutions of 1 to 40,000 are readily 

 prepared; such sera in dilutions of 1 to 10,000 may be regarded as specific for the identi- 

 fication of members of the group, if typical agglutination occurs. 



