AGf~ICULTURAL RESEARCH, PUSA.

BACILLUS TYPHOSUS 329
At an early stage of the disease-during the first week
or ten days-and in relapses, a condition of bacteriaemia
exists, and the typhoid bacillus can be demonstrated
by blood culture. It is also present in the spleen,
occurring in clumps. Typhoid bacilli arc frequently
present in large numbers in the gall bladder. 'fIley
may localise in the kidney and appeal" in the urine,
sometimes producing a marked bacilhn·ia. Localisation
1l1ay also occur ill bone-lnal'l'Ow.
'fhe bacillus is found in other lesions occurring as
complications or sequelae of typhoid fever-c.g. acute
suppnrative osteitis, abscess of the kidney, acute
cholecystitis, brollcho-pneumonia, empyema, ulcerative
endocarditis. Even in the suppurative lesions it
may be present in pure culture.
Infcction is by ingestion; from the small intcstinc thc
organism passes by thc lymphatics to the mcsenteric glanus,
and invades the lJluod pUi;sibly via the thuracic duet; tlw
liver, gl\ll bladder, Rplcen, kiuney, honc-n1[t1'l'ow, etc., then
beeomc infeded from thc circulation; from the gall bladdcr
a furthcr inva:;ion of the illtestine l'esults and the bacilli lllay
thell appear ill the facecs in appreciable llllIlllJers (vide p. a:Jl).
In 2 to 5 per cent. of cOllvalcscents, the typhoid
bacillus persists in the body sometimcs for indefinite
periods. In such " carriers" the bacilli are pl'cscnt in
the gall bladder, or in foci in the kidney, and are
excrcted in the faeces or urine.
B. typhOSU8 cannot exist as a saprophyte outside
the body, but it can survive long enough to be transmitted
by some vehicle of infection-e.g. sewage and
polluted water, shell-fish, and vegetables contaminated
with human excretal matter, house flies, articles of
food contaminated by carriers, etc. Milk is a good
culture medium for the typhoid bacillus, so that
contamination of milk-e.g. by carriers engaged in
dairy work - is a likely source of outbreaks of the
disease.
Serological React,ions.-'l'he serum. or aninlftls im.munised
with typhoid bacilli contains agglutinating
antibodies (vide p. aD) which are specific for the