HIDEYO NOGUCHI 469 



sue-dwelling treponemas, as a rule, confer no perceptible immunity, so far as natural 

 infection is concerned. 



The phenomena of immunity in leptospiral infections were first carefully studied 

 by Inada, Ido, and their co-workers,' in infectious jaundice in Japan. They demon- 

 strated that a person who has had an attack of infectious jaundice may remain im- 

 mune for many years, and the blood of persons recently recovered contains active 

 immune bodies which will give either Gabritschewsky's or Pfeiffer's phenomenon. 

 In experimental animals similar reactions were shown to follow the infection. Inada 

 and Ido- produced immune sera of high potency in horses for practical therapeutic 

 purposes and obtained excellent results when the serum was used early in the dis- 

 ease. Similar results were obtained by subsequent workers. 



In the case of yellow fever, also, one attack confers complete immunity which lasts 

 for many years; rarely have cases of second infection been reported within a period 

 of nine years. Provided that one lives continually in an endemic locality, where the 

 disease recurs at short intervals, one is protected for life by a single attack, because 

 a mild infection occurs while some immunity is still present, and protection is thus 

 reinforced. Persons born and residing in endemic foci seldom die from yellow fever, 

 and in the majority of instances such persons are unaware of having passed through 

 any infection. They lose their immunity, however, if they live outside the endemic 

 zone for more than ten years. 



The immunity phenomena in yellow fever closely parallel those of infectious 

 jaundice. There is a positive Pfeiffer reaction with convalescent yellow fever serum 

 and Leptospira interrogans. The killed culture of the interrogans, injected into normal 

 guinea pigs, gives the animals an increased resistance to the interrogans infection, 

 and a cubic centimeter of immune serum prepared with the interrogans may protect 

 guinea pigs against several million minimum lethal doses of culture. The efhcacy of 

 the interrogans vaccine and the a.nti-interrogans serum in human yellow fever has 

 been reported in a large number of cases.^ 



CULTIVATION 

 ANAEROBIC GROUP 



Treponema pallidum was first cultivated^ from the testicular syphiloma of rabbits 

 in a tall column of ascitic fluid or sheep-serum water containing fresh tissue (rabbit 

 kidney) and incubated at 37° C. under anaerobic conditions, a method based on the 

 anaerobic principle of Theobald Smith. ^ For the direct isolation of the parasite from 

 impure human materials,'' the medium was made solid by mixing two parts of agar 

 with one part of the ascitic fluid or serum, and purification was accomplished by suc- 

 cessive transplants into similar medium until the spirochetes were separated from 



' Inada, R., Ido, Y., Hoki, R., Ito, H., and Wani, H.: /. Expcr. Med., 24, 485. 1916; 27, 2S3. 

 191S. 



^ Inada, R., Ido, Y., Hoki, R., Ito, H., and Wani, H.: ibid., 24, 48.5. 1916. 



^Noguchi, H.: J. A.M. A., 77, 181. 192 1; /. Trop. Med., 28, 185. 1925. 



"• Noguchi, H.: /. E.Kper. Med., 14, 99. 191 1. 



5 Smith, T.: Ccntralbl.f. BaklerioL, 7, 502. 1890. 



'Noguchi, H.: J. Exper. Med., 15, 90. 191 2. 



