598 TREPONEMATA, SPIRONEMATA, LEPTOSPIRATA 
logically the two organisms are quite distinct, as shown by agglutina- 
tion reactions, and the Pfeiffer phenomenon.^ 
Pathogenesis.— //7//»a7?. —The Leptospirata are most numerous in 
the blood from the third to the sixth days, in moderately severe cases, 
and in early fatal cases they may be found in practically all organs 
of the abdominal cavity. After ten to fourteen days they disappear 
from the tissues, although the urine may remain infective from six 
to ten weeks, after apparent recovery. Rarely the organisms appear 
to be present in the feces, and even in the sputum. The elimination 
of the organisms from the tissues appears to depend upon the presence 
of specific lysins which appear within two weeks or more after infec- 
tion.^ The presence of these antibodies is shown by performing the 
Pfeiffer experiment— introducing the Leptospirata and immune serum 
into the peritoneal cavity of a normal guinea-pig. 
Animal.— The Japanese investigators have made the important 
discovery that wild rats harbor the infective agent. In the coal 
mine districts of Japan nearly 40 per cent of all rats examined showed 
the Leptospira, and in the United States, where examinations have 
been made, fully 10 per cent of wild rats are similarly infected.^ 
This was also found to be true in the trenches upon the European 
fields'* and also in areas apparently free from the disease.^ The organ- 
isms live in the kidney of the rat, apparently without noticeable 
detriment to the animal, and they are excreted in the urine. Guinea- 
pigs were infected by the bite of these rats and the evidence suggests 
that the Leptospirata may also pass through the unbroken skin of 
experimental animals. If such prove to be the case, the transmission 
of the disease to man in general does not depend of necessity upon 
the bite of infected rats; rather, it is through the urine, and subse- 
quent contamination of the skin, or even through mouth infection by 
soiled hands or food. 
The organisms found in the rats have been shown to be serologically 
like those of man; hence, indiscriminate infection of both rats and man 
may take place where they are closely associated. 
Bacteriological Diagnosis.— Human Cases. — 1. Examination of blood 
smears by the method of dark-field illumination for the actively motile 
Leptospirata with hooked or curved ends. 
2. Examination of blood smears with the appropriate Spirochtetal 
stains.'' 
3. Injection of blood into the peritoneal cavity of a guinea-pig. 
The earlier cases offer good prospects of successful demonstration of 
1 Noguchi: Jour. Trop. Med. and Hyg., May 15, 1925. 
2 The persistence of the Leptospirata in the urinary tract is not as yet satisfactorily 
explained. 
3 Noguchi: Jour. Exp. Med., 1917, 25, 755. Jobling: Jour. Am. Med. Assn., 
1917, 69, 1787. 
* Stokes, Ryle and Tytlor: Lancet, 1917, i, 142. 
6 Courmont and Durand: Bull. Soc. m6d. hop., Paris, 1917, 3d Series, 33, 115. 
6 See page 200. 
