486 THE SPIROCHETES 



onym Spirochaeta icterogenes Uhlenhuth and Fromme). The organisms as they occur 

 in water from the tap differ serologically and immunologically from L. icterohacmor- 

 rhagiae and are not pathogenic for guinea pigs, but on prolonged cultivation (impure) 

 some strains have gradually acquired the serological properties of the ideroliaemor- 

 rhagiae and have finally become suflficiently virulent to induce typical hemorrhagic 

 jaundice in the guinea pig.' Immune sera prepared with the pathogenic strain pro- 

 tect guinea pigs against a virulent strain of the icterohaemorrhagiae, and animals which 

 have recovered from an attack of the mutated water leptospiras resist an infection 

 with the icteroliaeniorrhagiae, and vice versa. Other strains of the water leptospiras, 

 which have not been completely converted into pathogenic forms, do not yield anti- 

 sera protective against the icterohaemorrhagiae, and exhibit serological differences 

 among themselves. It is suggested by Uhlenhuth and Zuelzer that the water lepto- 

 spiras are taken up by some animal such as the rat, in whose body they are con- 

 verted into a pathogenic parasite capable of infecting man. The immediate source 

 of infection in bathing pools or slime is, according to this theory, the urine of infected 

 rats. 



Numerous investigators have since found free-living leptospiras in both fresh and 

 salt water and in many different countries. The organisms are to be found in any 

 water that comes in contact with objects covered with sUme, and they are present in 

 greater numbers in the slime than in the water. They may be very numerous in some 

 specimens — one or two to each microscopic field — and are readily demonstrable by 

 darkfield examination. Coles' recently found that leptospiras, together with flagel- 

 lated protozoa, may be found in infusions made from decayed leaves in sterilized 

 water, a fact which explains their presence in mountain ditches, where they have been 

 found by the writer (Catskill Mountains of New York). It is not impossible, how- 

 ever, that wild rats or certain tree-climbing rodents might infect such water. 



Although most investigators have found the inoculation of water or sHme con- 

 taining free-living leptospiras to give negative results, a pathogenic leptospira may be 

 occasionally present under natural conditions, as shown by the recent experiments 

 of Buchanan,^ who infected guinea pigs with slime collected from the roof of a coal 

 mine in East Lothian, Scotland. Moreover, according to Toyama,^ and Buchanan, 

 Leptospira icterohaemorrhagiae may survive for two months in soil, provided the re- 

 action is neutral or slightly alkaline. 



In recent years the water leptospiras have been isolated by a number of workers 

 in pure culture by filtration through bacterial filters, usually Berkefeld V (pores 0.7- 

 I /x) and N (pores 0.4-0.6 ju). Bauer^ obtained thirteen strains in West Africa; Moch- 

 tar,'' three strains in Holland; and Dimitroff,^ thirty-seven strains in the United 

 States. One strain has been isolated in the writer's laboratory from icebox slime. 



' Zuelzer, M.: Cenlralbl. f. Bakleriol., Orig., 89, 171. 1922. 



2 Coles, A. C: /. Trap., Med., 29, 170. 1926. 



3 Buchanan, G.: Spirochetal Jaundice, Med. Research Council., Spec. Rep. (113th ser.). 1927. 

 4Toyama, Y.: So. Rep., Gov. Inst, for Infect. Dis., i, 197. Tokyo, 1922; Japan Med. World., 4, 



193. 1924. 



5 Bauer, J. H.: Ivc. cit. * Mochtar, A.: loc. cit. ^ DimitrolY, V. T.: loc. oil. 



