After the guilt of the female "stegomyia" mosquito was firmly established the next problem was to find a method of combating her work. Dr. Reed and his associates thought that it might be done through a process of immunization, using the mosquito to bite patients with very mild cases, and after the necessary period of incubation, to transmit the disease to those who were to be rendered immune. It was soon found, however, that there was no method of transmitting a mild infection, and the next problem was to combat the work of the mosquito by isolation of yellow fever patients, and by the extermination of the mosquitoes themselves.
In Havana at this time there was another army surgeon who was destined to write his name high upon the pages of medical achievement. He was Dr. William C. Gorgas. Under the patronage of Gen. Leonard Wood, himself a physician and alive to the lessons of the yellow fever commission's investigations, Major Gorgas undertook to apply the doctrine of yellow fever prevention promulgated by the commission, and his efforts were attended with brilliant success. The result was that Havana, in particular, and Cuba, in general, were freed from this great terror of the Tropics. When President Roosevelt came to provide for the building of the Panama Canal one of his earlier acts was to appoint Dr. Gorgas the chief sanitary officer of the Canal Zone.
At first there was difficulty in establishing practical sanitation in Panama. The chief sanitary officer was then a subordinate of the commission, and, along with all of the other men who were trying to do things on the Isthmus, he found himself hindered by unsatisfactory conditions both as to supplies and as to force; consequently, his work was no more satisfactory to himself than it was to the commission or to the American people. Under these conditions an epidemic of yellow fever broke out in Panama in 1905, and it was not long before the yellow fever mosquito had seemingly established an alibi and had secured a reopening of her case before the jury of public sentiment. People, to emphasize their disbelief in the mosquito theory of the transmission of the disease, tore the screens from their doors and windows, and otherwise proclaimed their contempt for the doctors and their doctrines. This matter went so far that the Isthmian Canal Commission proposed not only a change in method but a change in personnel as well.