72 SPIROCH^TES 



culture, the treatment of yellow fever consisted only of careful 

 nursing and in the maintenance of the best hygienic conditions: 

 there are no drugs known which have any value as specifics 

 against the disease. Recently, however, Noguchi and his fellow 

 workers at the Rockefeller Institute have demonstrated the 

 development of antibodies in animals and man inoculated with 

 killed cultures of the leptospira, and from the results of vaccin- 

 ation in guinea pigs, concluded that with the inoculation of a 

 sufficient quantity of dead organisms they were rendered immune 

 to subsequent infection. Distinctly encouraging results have been 

 obtained from the vaccination of human beings. Of 8000 non- 

 immune persons vaccinated in tropical America, excluding those 

 exposed to the disease just before or immediately after vaccin- 

 ation, no cases of yellow fever have developed, while among 

 unvaccinated persons during the same period and in the same 

 locality there have been about 700 cases of the disease. A thera- 

 peutic serum has also been prepared for treatment of yellow fever. 

 According to Noguchi persons treated with a sufficient quantity 

 of the serum before the third day of illness have invariably re- 

 covered. By the fourth day of illness the injuries to organs are 

 so great as to be irreparable in severe cases. The usual 50 to 

 60 per cent mortality from yellow fever was reduced to 9 per cent 

 by the use of the serum, while still in an experimental state. 



The eradication of yellow fever consists largely in the applic- 

 ation of sanitary measures to exterminate the yellow fever mos- 

 quito Aedes calopus, but in the face of an epidemic this can now 

 be supplemented by vaccination to cut off the supply of non- 

 immunes from infected mosquitoes. According to Noguchi a 

 threatening epidemic in Central America in 1920 is reported to 

 have been checked by these methods within a month, i.e., before 

 the development of the second set of cases. The value of im- 

 munization as an emergency measure does not, however, mini- 

 mize the importance of anti-mosquito campaigns, since the elimin- 

 ation of both factors non-immune human beings and infected 

 mosquitoes is necessary for the eradication of yellow fever. The 

 habits of the mosquito, as described on p. 444, are such that it is not 

 difficult to combat and successful campaigns against it, with a re- 

 sultant obliteration of yellow fever, have been made in many places. 

 Panama, Havana, Rio de Janiero, and recently Manaos and 



