TYPHOID ‘^BACILLUS CAKKIEES/ ’ 169 
and the other, she thought, of diarrhea, shortly before the onset of 
her symptoms. 
Drigalski and Conradi (1902) isolated the typhoid bacillus from 
the stools of four persons who showed no symptoms of any kind, but 
who had been in close contact with cases of typhoid fever. 
Donitz (1903) mentions two cases of typhoid fever in children who 
were probably infected by their mother, who, though apparently 
well, had typhoid bacilli in the urine. She had probably acquired 
the infection from a case of the disease which had occurred on the 
premises four months before. 
Liebetrau (1906) reports the case of a woman, an attendant in a 
prison, who was found discharging bacilli in the feces two years after 
having nursed two cases of the disease. She was well and had never 
been sick. The occurrence of 4 cases of typhoid in inmates, who had 
been there so long that they could not have acquired their infec- 
tion outside, led to her discovery and isolation, after which no more 
cases appeared. 
No exact estimate of the frequency of chronic typhoid bacillus 
carriers can be made at this time, the literature on the subject being 
as yet too scanty. A working idea, however, may be formed. 
The frequency with which the typhoid bacillus has been isolated 
from the urine varies widely, as may be seen from the table. This 
variation depends, in part, on differences in technique and, in part, on 
the stage of the disease in which the studies were made and the fre- 
quency with which the examinations were repeated in each case. 
Considering only the studies (indicated in the table by a *) made on 
cases taken at random, since the introduction of the serum agglutina- 
tion test for the identification of the bacillus, and averaging the re- 
sults, it would appear that the typhoid bacillus occurs in the urine 
in about 16 per cent of cases. 
At the typhoid observation station at Idar, Lentz (1905) found 
that 4 per cent of all cases observed became chronic typhoid bacillus 
carriers. He gives in tabulated form the results obtained at the 
other typhoid observation stations, which show quite a marked vari- 
ation. Averaging the results obtained by Lentz (1905), Klinger 
( 1906), and von Drigalski ( 1906), we find that of 1782 cases of typhoid 
fever 53, or about 3 per cent, became chronic carriers. 
An explanation of the long existence of the typhoid bacillus in the 
stools is to be found, at times, in chronic typhoid ulcerations, but 
more commonly in the infection of the gall bladder with this bacillus. 
Nieter and Lief man (1906) report a case which is of interest in this 
connection. In the course of an investigation of the cause of the 
persistent occurrence of cases of dysentery and typhoid fever in a 
certain insane asylum they found amongst others a case of chronic 
