246 MOSQUITOES OF NORTH AMERICA 



Emilio Eibas, Director of the Health Service of Sao Paulo, and Dr. Adolfo Lutz, 

 Chief of the Bacteriological Institute of the same city, repeated the experiments 

 in yellow-fever inoculation by means of the yellow-fever mosquito. A com- 

 mission, composed of Doctors L. Barreto, A. G. da Silva Eodrigues, and A. J. 

 de Barros, was created to carry on the work. Doctor Eibas and Doctor Lutz 

 were the first who were pierced by infected mosquitoes, but the results were 

 negative, undoubtedely because both men had lived for many years in the midst 

 of yellow fever and had become immune. With three other persons, however, 

 the Brazilian commission succeeded in January, 1903, in producing character- 

 istic yellow fever by having them bitten by infected Aedes calopus. These mos- 

 quitoes came from the town of Sao Simao, situated several hundred kilometers 

 away from Sao Paulo, and had been allowed to bite yellow-fever patients in 

 that town where there was at the time an epidemic of the disease. This ex- 

 periment was a strongly convincing one, for the reason that at the time there 

 were absolutely no cases of yellow fever in Sao Paulo and no one could point out 

 any other method of contagion than by the bite of these mosquitoes brought 

 from the yellow-fever locality. 



In addition to these Brazilian results, the French government, in 1901, sent 

 a mission to Eio de Janeiro, composed of Messrs. Marchoux, Salimbeni and 

 Simond, under the scientific direction of the Pasteur Institute. This Commis^ 

 sion brought about some very exact confirmatory results, and in the months of 

 May and June, 1903, succeeded in producing yellow fever in three cases by in- 

 oculation by infected Aedes calopus. The report of the Commission and the 

 subsequent papers by Marchoux and Simond, published by the Pasteur Institute 

 in several parts extending down to 1906, form a notable contribution to the his- 

 tory of yellow fever. Their opportunities were great, their methods were most 

 exact, and they confirmed in every respect the results obtained by the American 

 commission. Their conclusions, as published in the Annals of the Pasteur In- 

 stitute, in November, 1903, are sufficiently important to quote : 



"(1) The serum of a patient is virulent on the third day of the illness. 



"(2) On the fourth day the blood of a yellow-fever patient no longer contains 

 the virus, even when the fever is higher. 



"(3) One-tenth cc. of virulent serum injected under the skin is sufiicient to 

 produce yellow fever. 



"(4) The virus of yellow fever placed upon an abrasion of the skin does not 

 give the fever. 



"(5) In the serum of a patient the virus of yellow fever passes through a 

 Chamberland F filter without dilution. 



"(6) Under the same conditions, it does not appear to pass through filter B. 



"(7) The virulent serum kept from air at a temperature of from 34 to 30 

 degrees C. is inactive at the end of 48 hours. 



"(8) In defibrinated blood kept under vaseline oil at temperature from 24 to 

 30, the microbe of yellow fever is still living at the end of five days. 



"(9) At the end of eight days defibrinated blood kept under the same con- 

 ditions no longer contains the active virus. 



"(10) The virulent serum becomes inoffensive after a heating for 5' to 55° C. 



"(11) A preventive injection of serum heated for 5' to 55° gives relative 

 immunity, which, followed by inoculation with a very small quantity of virus, 

 can become complete. 



