246 MOSQUITOES OF NORTH AMERICA 
Emilio Ribas, 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 Rodrigues, and A. J. 
de Barros, was created to carry on the work. Doctor Ribas 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 Aédes 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 So 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 Rio 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 Aédes 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 sufficient 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 24 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. 
