596 TREPONEMATA, SPIRONEMATA, LEPTOSPIRATA 
ysms usually number four or five with corresponding periods of apyrexia 
before the onset of convalescence. 
Morphology.— Spironema duttoni (Spirochseta duttoni) is somewhat 
thicker and longer than Spironema recurrentis; it measures about 
0.45 to 0.5 micron in diameter and from 24 to 30 microns in length. 
The motility is similar to that of the organism of European relapsing 
fever. Noguchi^ has grown Spironema duttoni in pure culture. 
Immunity.— Rats are readily infected with the organism; those 
which have recovered from infection with Spironema duttoni are 
easily infected with Spironema recurrentis and lice lersa. They are 
refractory to a second injection of the same organism, indicating that 
the immunity conferred by one Spironema is not protective against 
infection with Spironemata of another type. 
Ross- found that the horse tick (Ornithodorus moubata) would 
transmit the disease from man to monkey, provided the insect bit the 
man during, or very shortly before, the febrile period. The organism 
may be demonstrated in the ovaries and eggs of female ticks which 
have fed upon man. This appears to be a case of true hereditary 
transmission; the organism is transmissible by the adult and larval 
insects, and through the eggs as well. 
INFECTIOUS JAUNDICE. 
Infectious jaundice, Weil's disease or Spirochfetosis icterohaemor- 
rhagica, is an acute infectious disease, which usually begins with 
malaise and considerable prostration, followed by gastro-intestinal 
symptoms, and fever of moderate intensity. Practically all patients 
exhibit jaundice. Mild cases merge almost imperceptibly into the 
syndrome of catarrhal jaundice, and may thus escape recognition as 
belonging to the infectious group. The more severe, and therefore 
more nearly typical cases, agree with those first described by Weil.^ 
Epidemics of the disease have been reported in Europe, Asia and 
Japan. They are also recorded in the United States, for the most part 
east of the Rocky Mountains thus far. The disease is more preva- 
lent in winter than in summer. Those working or living in mines, 
sewers, in the trenches, or in any situation in proximity to wet soil 
are more prone to infection. The etiological agent appears to be a 
spiral organism, first called Spirocha^ta icterohaemorrhagise, but in 
accordance with the newer classification of spiral organisms, Lepto- 
spira icterohwmorrhagiae. 
The infectious nature of the disease appears to have been discovered 
independently in Japan, and in Germany. The Japanese discoveries 
were completed in 1914-1915 and published in Japanese. A report 
> Jour. Exp. Med., 1912, 16, 202. 
2 British Med. Jour., 1905, i, 280. 
' Uebcr einc oigenthumliche, niit Miltztumor, Ikterus uiid Nephritis einhergehende 
Infektionskrankheit, Deutsch. Arfh. t. kliii. Med., 1886, 39, 209. 
