From the earliest history of yellow fever in our country there have been evidences of its having been imported from some foreign place, usually the countries to the southward within the tropics. This importation has usually taken place during the prevalence of warm weather in the spring, summer or fall months, and could be traced to one of the intertropic endemic centers. During cold weather, the disease would disappear either entirely or to a great extent.
Its continued presence, however, from year to year in some of our southern cities, and its recrudescence with the advent of the warm weather of the spring, following its epidemic presence during the summer, induced numbers of prominent observers to believe that this disease was indigenous to our southern latitudes, and, like malarial infections, depended on unsanitary conditions.
The cessation of the fever following the institution of an adequate system of maritime quarantine protection
WASDIN E. YELLOW FEVER; ITS NATURE AND CAUSE.. JAMA. 1900;XXXV(14):867-875. doi:10.1001/jama.1900.24620400015001c