“Recognizing its importance, Aedes aegypti should be studied as a long-term national, regional, and world problem rather than as a temporary local threat to the communities suffering at any given moment from yellow fever, dengue or other aegypti-borne disease. No one can foresee the extent of the future threat of Aedes aegypti to mankind as a vector of known virus diseases, and none can foretell what other virus diseases may yet affect regions where A. aegypti is permitted to remain.”