■'582 THE ALCALIGENES—DYSENTERY— TYPHOID GROUP 
(hog cholera bacilhis), inchiding B. psittacosis, B. sertrycke and some 
strains of B. typhi murium; (4) B. enteritidis, inchiding the Danysz 
bacilhis, B. morbificans bovis and some strains of B. typhi murium. 
This classification, if substantiated, possesses the advantage of sepa- 
rating those organisms which cause paratyphoid fever, the alpha and 
beta types, from the bacilli more commonly associated with the lower 
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 occasion- 
ally the choleraic symptoms of meat poisoning may be elicited by 
paratyphoid bacilli, and that the symptoms of paratyphoid fever may 
follow infection with B. enteritidis or B. suipestifer. 
Pathogenesis. — .l??M»o/.— The members of the Paratyphoid Group 
are, as a rule, very pathogenic for small laboratory animals. The 
intraperitoneal injection of very minvite amounts of bacilli usually 
causes acute death in guinea-pigs and mice. Rats are somewhat 
more resistant. B. typhi murium and other "rat viruses" produce 
a fatal enteritis in mice and rats; the bacilli are present not only in 
the intestinal contents, they may be obtained from the tissues and 
organs postmortem 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. 
Hu7na7i.— 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 con- 
fused with true cholera;- infection usually follows the ingestion 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;^ 
(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 D. Jong: Les relations des infections paratyphique de I'homme et des animaux, 
Rev. Gen. de med. veterin., 1913, vol. 22. 
2 Hetsch.: Klin. Jahrb. 1907, 16, 267. 
^ Mayer: Mi'mchen. med. Wchnschr., 1905, 52, 2261. Shibayama: Miinchen. med. 
Wchnschr., 1907, 54, 979. 
