HIDEYO NOGUCHI 489 



terohaemorrhagiae. Uhlenhuth and Zuelzer' found that a leptospira present in tap 

 water in Berlin may produce icterohemorrhagic disease in guinea pigs after cultiva- 

 tion together with bacteria for several generations. The strain was obtained in pure 

 culture from the inoculated guinea pigs and was found to be serologically as well as 

 pathogenically identical with L. icterohaemorrhagiae. Uhlenhuth and Zuelzer con- 

 cluded that the non-pathogenic, serologically distinct, free-living leptospira had been 

 converted into L. icterohaemorrhagiae. Other investigators have found their culture 

 of water leptospiras, whether pure or impure, to be devoid of virulence for guinea 

 pigs. It has long been known that epidemics of infectious jaundice may arise as a 

 result of bathing in river water. It seems probable that the source of infection is the 

 urine of wild rats deposited near the shore, and that the micro-organism enters the 

 body through the skin of the feet. How rats come to act as carriers of a micro-or- 

 ganism which is pathogenic for certain other mammals though harmless to the rat 

 itself is an interesting problem. Uhlenhuth and Zuelzer think that the water lepto- 

 spira is rendered pathogenic for man by passage through the rat. The writer has 

 injected water containing leptospiras into white rats but has never detected the or- 

 ganisms in the kidneys of the animals. 



L. icterohaemorrhagiae passes through Berkefeld filters V, N , and W ,- but can 

 rarely be detected microscopically in the filtrates. Its presence is shown by the in- 

 fectiousness of the filtrates, or by cultivation by the method described elsewhere 



(P- 473)- 



L. hehdomadis {Fig. 122). — L. hebdomadis was first isolated by Ido, Ito, and 

 Wani^ from young guinea pigs inoculated with blood of patients suffering from a dis- 

 ease known in Japan as nanukayami ("seven-day fever"), a non-fatal infection oc- 

 curring during the summer months among field workers. The disease begins with 

 all the acute symptoms characteristic of infectious jaundice, but only icterus and 

 hemorrhages develop. 



L. hebdomadis is present during the febrile period in the blood of guinea pigs. 

 The symptoms in guinea pigs are slight hemorrhage and mild jaundice; the infec- 

 tion is never fatal. The serum of convalescent patients or animals contains lysins 

 for L. hebdomadis but none for L. icterohaemorrhagiae. Guinea pigs which have passed 

 through infection with one of these leptospiras are just as susceptible to the other as 

 are normal animals. 



Morphologically, L. hebdomadis is decidedly longer than L. icterohaemorrhagiae 

 and is more closely wound. Living specimens rarely show the hooked ends, but fixed 

 and stained individuals are characteristically hooked. The organism is without doubt 

 a member of the leptospira group. 



The natural host of L. hebdomadis is the field mouse, Microtus montebelli, which 

 abounds in certain regions of Japan and probably disseminates the organism through 

 its urine. 



L. pyrogenes. — In certain parts of Sumatra an acute febrile disease, resembling a 

 mild form of Weil's disease, or dengue, is endemic. Verwoort^ in Deli (1923) found in 



' Uhlenhuth, P., and Zuelzer, M.: loc. cil. 



^ Inada, R., Ido, Y., Hoki, R., Kaneko, R., and Ito, H.: loc. cit. 



3 Ido, Y., Ito, H., and Wani, H.: J. Exper. Med., 28, 435. 1918. '• Verwoort, H.: loc. cit. 



