348 THE ALCALIGENES DYSENTERY TYPHOID 



animals, of which the hog cholera bacillus and B. enteritidis are the 

 types. This classification has not been universally accepted, how- 

 ever. Doubtless the multiplicity of strains which have received the 

 same name has led to confusion in standard type organisms which are 

 especially essential in this line of investigation. It is not an assured 

 fact that the paratyphoid bacilli, alpha and beta, are restricted to the 

 production of paratyphoid fever in man; nor can it be stated definitely 

 that B. enteritidis and the hog cholera bacillus consistently cause 

 meat poisoning. Available information suggests that occasionally 

 the choleraic symptoms of meat poisoning may be elicited by para- 

 typhoid bacilli, and that the symptoms of paratyphoid fever may 

 follow infection with B. enteritidis or B. suipestifer. 



Pathogenesis. Animal. The members of the Paratyphoid Group 

 are, as a rule, very pathogenic for small laboratory animals. The intra- 

 peritoneal injection of very minute amounts of bacilli usually causes 

 acute death in guinea-pigs and mice. Rats are somewhat more 

 resistant. B. typhi murium and other a rat viruses" produce a fatal 

 enteritis in mice and rats ; the bacilli are present not only in the intes- 

 tinal contents, they may be obtained from the tissues and organs post- 

 mortem as well. Bacilli belonging to the Paratyphoid Group have 

 been isolated from epizootics and sporadic cases of enteritis in cattle, 

 parrots, and rodents. The organisms appear to be widely distributed 

 among the lower animals. 



Human. Three types of disease are produced in man by the bac- 

 teria of the paratyphoid group: (a) meat poisoning: the symptoms 

 are choleraic in character, and they may be severe enough to be 

 confused with true cholera; 1 infection usually follows the ingest ion 

 of imperfectly cooked beef or pork contaminated with B. enteritidis 

 or the hog cholera bacillus. Somewhat similar symptoms have 

 resulted from the accidental ingestion of the "rat virus" of Danysz 

 and others; 2 (b) paratyphoid fever, a disease clinically resembling 

 mild typhoid fever, usually caused by B. paratyphosus alpha or B. 

 paratyphosus beta; (c) a rare type of disease, pneumonic in character, 

 produced by B. psittacosis, which produces an epizootic disease among 

 parrots. 



(a) Meat Poisoning. The disease is more prevalent in summer and 

 fall than it is in winter and spring, probably due in part to decreased 



1 Hetsch, Klin. Jahrb., 1907, xvi, 267. 



2 Mayer, Miinchen. med. Wchnschr., 1906, No. 47; Shibayama, Miinchen. med. 

 Wchnschr., 1907, 979. 



