148 
PRINCIPLES OF BACTERIOLOGY 
utes at 56° C. destroys it. On artificial culture it will 
remain for many months, if sufficient moisture is sup¬ 
plied. It will keep alive for many months on ice and in 
water. It is killed somewhat less readily by ordinary dis¬ 
infectants than most of the bacteria, but 1:500 solution 
of bichloride of mercury will kill it in a few minutes. 
V. Disease Production, Mode of Infection, Disinfec¬ 
tion and Prophylaxis 
Bacillus typhosus causes typhoid fever. During the first 
week or ten days the bacilli are found in the blood and 
“rose spots” (the rash of typhoid fever). Quite often 
the bacilli, after the patient recovers lodge in the gall 
bladder whence they are continually discharged into the 
intestine and thus appear in the feces, in this way while 
the patient is well and immune, he may become the so- 
called “bacillus carrier” and be a temporary or perma¬ 
nent source of danger to the community. For this reason 
all patients who have recovered from typhoid fever, 
should have their stools examined, and, if typhoid bacilli 
be found, should be warned to take special precautions 
about disinfecting the stools, etc. 
In about 25 per cent of cases the typhoid bacilli may 
be cultured from the urine. 
Very frequently the presence of this bacteria in the 
gall bladder causes its inflammation (cholecystitis) and 
the gallstones. 
Suppurations may be caused by the typhoid bacillus 
especially in the long bones and in the ribs or spine and, 
not infrequently, meningitis. 
Typhoid fever is always with us, but from time to time 
severe epidemics take place. 
Practically all cases of typhoid fever are contracted 
