LEPTOSPIRA ICTEROHMMORRHAOIM 919 



sharp and pointed as in pallidum, but more or less rounded. It is non-pathogenic for 

 rabbits and monkeys. 



Treponema phagedenis. — This organism was cultivated by Noguchi (1912/) from 

 a phagedenic ulcer on the labium of a woman. Growth occurred in ascitic agar 

 medium under anaerobic conditions in the absence of kidney tissue. In the original 

 lesion the spirochsetes were 4^30 /< in length and 0-75 n in thickness ; in culture their 

 length was less variable, being 10-15 ^. The number of spirals varies from one to eight, 

 and there is great variation in the length of each spiral. Some organisms appear nearly 

 straight. The ends are pointed, but not drawn out. Other spirochsetes have been 

 described in ulcerative lesions round the genital regions, such as Trep. balanitidis, Trep. 

 fseudo-pallidum, and Tre-p. gangrenosa nosocomialis (see Noguchi 1912/). 



Spirochaetes in the Human Mouth. — Spirochaetes of different types have been described 

 in the mouth ; they can generally be seen in scrapings from between the teeth. Some- 

 times organisms morphologically indistinguishable from Trep. pallidum are found. Noguchi 

 (1912a) succeeded in cultivating what he regards as two separate species. Trep. micro- 

 dentium is a short spirochsete about 3^ p. long by 0-25 p wide, having shallow rectangular 

 curves of constant size. The ends are drawn out and pointed. In culture it is said by 

 Segurn and Vinzent (1938) to be an actively motile organism, 4-7 fi long, having 6-12 well- 

 defined regular spirals. In serum agar tissue medium it forms a haze near the bottom 

 of the tube, gradually becoming denser and spreading upwards tiU it is witliin 2-3 cm. 

 of the surface. Growth is anaerobic. Trep. macrodentium is a larger organism, varying 

 from 3-8 ju long by 0-7-1 -0 /i broad in young cultures, and having 2-8 irregular shallow 

 curves ; the ends taper off abruptly. In older cultures the organisms are longer and 

 thinner. In serum agar tissue medium growth occurs under anaerobic conditions in the 

 form of a faint almost transjjarent haze. For methods of isolating and culturing the 

 mouth spirochaetes, reference may be made to papers by Seguin and Vinzent (1938), 

 Kast and Kolmer (1940), and Wichelhausen and Wichelhausen (1942). 



Vinzent and Daufresne (1934), working mainly with pure cultures, have provisionally 

 classified the mouth spirochaetes into groups, which they label A to G. Group B corresponds 

 to Trep. microdentium and Group F to Trep. macrodentium. 



Treponema cobayae. — Found by Knowles and Basu (1935) in the blood of guinea-pigs. 

 Blood parasite belonging to the relapsing fever group. Thin, delicate spirochsete, 13-5-23 n 

 in length, with finely tapering ends ; average length of spirals 3-6 f.h. Can be cultivated 

 in Galloway's medium. Inoculation of guinea-pigs with infected blood is followed, after 

 an incubation period of 2 to 6 days, by a febrile disease accompanied by the presence of 

 spirochaetes in the blood. Fully virulent strains kill 30-60 per cent, of inoculated animals. 

 Relapses may occur in animals that recover from the first attack. White rats and rabbits 

 are also susceptible to infection. 



Blood spirochaetes have been described in other animals, such as the rabbit and the 

 mouse (see Knowles and Basu 1935). 



Leptospira icterohsemorrhagise 



Isolation. — First adequate description given in 1915 by Inada and his colleagues in 

 Japan (see Inada et al. 1916), who observed it in the blood and tissues of patients with 

 Weil's disease. 



Synonyms. — Spirochceta icterohcemorrhagioB ; Spirochceta icterogenes. 



Morphology. — Very delicate organism whose morphology can be studied satisfactorily 

 only by dark-ground illumination. The spirals are too fine to be properly resolved in 

 stained preparations. In length it is about 6-12 /<, and 0-1-0-15 ix in thickness ; forms 

 as short as 4 ^ and as long as 25 fi may sometimes be observed. It contains a number of 

 perfectly regular closely-wound spirals, each of which is about 0-5 p long or even less, 

 and has an amplitude of 0-5 (a. Near the extremities the spirals become even closer. 

 Secondary waves commonly appear during motion, but the spirochaete has a marked 



