YELLOW FEVER AND THE LEPTOSPIRA 881 



a Berkefeld filter. The filtrability of the virus has recently become 

 doubtful in view of the researches of Noguchi. 



Eecently, Noguchi 19 has carried out investigations which promise 

 to settle the etiological problem in yellow fever conclusively. 

 Noguchi in 1918 carried out extensive studies in the Yellow 

 Fever Hospital at Guayaquil, where he began by observing 172 

 typical cases of the disease, studying them clinically and patholog- 

 ically. We mention this because the only possible source of error 

 in his investigations seems to us to be that of mistaking of cases 

 of infectious jaundice for yellow fever, which, of course, is possible 

 in view of the clinical similarity between the diseases, as emphasized 

 by Nishi. It is important, therefore, to mention that Noguchi 

 worked on what he considered classical cases of yellow fever in a 

 Yellow Fever Hospital where he was aided by physicians familiar 

 with the disease. He began by injecting blood from these cases 

 in the first week of the disease, into a large number of different 

 animals. The only animals with which he had success, however, 

 were guinea-pigs. With the blood of early cases he inoculated 

 seventy-four guinea-pigs from twenty-seven cases of yellow fever. 

 Of these, eight, representing six cases, came down with symptoms 

 resembling human yellow fever. After an incubation period of three 

 to six days, the guinea-pigs showed a marked rise of temperature, 

 eonjunctival congestion, leucocytosis followed by progressive leuco- 

 penia, and a drop of temperature after a few days. Jaundice was 

 noticed during this period, and hemorrhages from the nose and anus 

 were occasionally observed. At autopsy the tissues were deeply 

 jaundiced and the organs hyperemic. Hemorrhagic spots were 

 found in the lungs and in the intestinal mucous membrane. 



In the blood, liver and kidneys of the guinea-pigs experimentally 

 infected, Noguchi found the organism which he calls the Leptospira 

 Ictero-Hcemorrhagice. This organism resembles quite closely the 

 causative agent of infectious jaundice. In general, his monkey ex- 

 periments were negative in all ,species except the Marmosets (Midas 

 Oedipus and Midas Geoff royi). 



The examination of the blood of patients by the dark field in 

 Noguchi 's 20 hands never yielded large numbers of organisms. In 

 careful examinations made on twenty-seven cases he found them 

 in three only. He never saw them in urine, but one guinea-pig 



19 Noguchi, Jour. Exper. Med., 29, 1919, 547-596. 



20 Noguchi, Jour. Exper. Med., 30, 1919, 87. 



