384 THE ALCALIGENES— DYSENTERY— TYPHOID GROUP 
India, is more frequently an infection with the (ilpha organism; in 
Europe the beta organism is much more frequently reported. Both 
types are found in the United States.^ Tht organisms are occasion- 
ally found in the intestinal contents and feces of young children and 
adults who give no history of infection. 
The incubation period of paratyphoid fever varies from eight to 
twenty days; the average is about two weeks. The onset is gradual; 
the usual prodromal symptoms are severe head- and backache, malaise 
and anorexia. Bronchitis and sore throat are common. There may 
be an initial chill, then the temperature rises rather rapidly to a 
maximum of 103° to 105° C; after the fifth to the seventh "day it 
falls slowly; it is normal by the end of the second week. Rose spots 
are occasionally seen early in the disease. Less commonly acute 
gastro-enteric symptoms, resembling those of meat poisoning, com- 
plicate the clinical picture. Paratyphoid fever is a bacteriemia, very 
similar to typhoid fever in this respect The mortality is low, averag- 
ing from 1 to 2 per cent of all cases. The lesions observed post- 
mortem are intense hyperemia of the gastro-intestinal tract, usually 
with superficial ulcerations in the ileum and cecum, not necessarily, 
however, involving Beyer's patches. Acute splenic tumor is usually 
not a feature of paratyphoid infections. The bacilli may be isolated 
from the heart blood and visceral organs. 
Bacterial Diagnosis. — (a) Isolation of Bacilli.— Blood cultures made 
during the first week are frequently positive. The organisms are 
usually present in the feces, occasionally in the urine. The identifi- 
cation of the bacilli depends upon the cultural characters outlined 
above; gas production in glucose and mannitol, no liquefaction of 
gelatin, and a permanent acidity in litmus milk (alpha type) or a 
transient acidity followed by a progressively alkaline reaction in this 
medium (beta type) ; the beta types ferment xylose, but the alpha type 
fails to induce fermentation. Isolation from the feces is made upon 
lactose agar plates with the Andrade indicator 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 .- 
(b) Serological.— As a routine measure the diagnosis of paratyi)hoid 
fever by the agglutination test is unreliable. Not hifrequently the 
blood serum of a patient agglutinates typhoid bacilli in dilutions 
approaching those ultimate for the homologous organism. The prac- 
tice of prophylactic vaccination with a triple vaccine containing 
B. typhosus, B. paratyphosus alpha and beta, must be borne in mind 
1 Gwyn: Bull. Johns Hopkins Hosp., 1898, 9, 54. Gushing: Ibid., 1900, 11, 156. 
Buxton and Coleman: Proc. Path. Soc, New York, February, 1902. Proescher and 
Roddy: Jour. Am. Med. Assn., 1909, 52, 470. Kendall, Bagg and Day: Boston Med. 
and Surg. .Jour., 1913, 169, 741. Kendall and Day: Ibid., 1913, 169, 753. 
- Sera that ^vill 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. 
