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General William C. Gorgas of the United States Army Medical Corps rid
Havana of yellow fever by destroying breeding places of the mosquito,
thus ending a 212-year-reign of the disease there; later he applied the
same method at the Isthmus of Panama, making possible the building of
the Panama Canal. Epidemics were stopped at Laredo, Texas, in 1904
and at New Orleans in 1905, and all South American seaports were freed
from the disease a few years later. As a result yellow fever has not
appeared in the United States for 35 years. (10)

Physicians were jubilant over the successful campaigns against
the disease, but their habit of thought precluded the belief that it had
indeed been exterminated. Furthermore, research had shown that the
fever reached seaports from inland sections of tropical countries, but
failed to disclose the exact spots in which it had originated.

Consequently, in 1916 the Rockefeller Foundation appointed a
committee, headed by General Gorgas, to make a survey throughout South
and Central America in the hope of banishing the disease for all time. By
1921 it had been eliminated from Peru, Ecuador, and most of the extreme
western sections of the continent. The task in Central America was more
difficult. Despite mosquito control measures, out-breaks occurred at Vera
Cruz and Tampico in 1920 and in San Salvador in 1924. Rigid control
campaigns resulted in eradication of the disease in Mexico in 1922. (11)

Encouraged by these successes, the medical profession was
beginning to believe that yellow fever conquest might be extended to all