Few books can have had longer gestations than this one. I first became aware of the devastating lethality of yellow fever in the winter of 1979–1980 when reading documents about eighteenth-century Cuba in the Archivo General de Indias in Seville. I was then a twenty-five-year-old graduate student researching a dissertation, trying to live on $125 a month, lonely and often cold and hungry, aware that Seville had many charms available in the hours after the archive had closed but that I could not afford any more costly than walking the avenues and visiting the glorious cathedral. Reading about yellow fever was good for my shaky morale: At least I was not in searing heat, plagued by mosquitoes, and wracked with a deadly virus.

My dissertation had a few references to yellow fever. In the two years after I completed that justly neglected document, I had the good fortune to be flamboyantly unsuccessful in the academic job market, providing me with an informal post-doc financed by odd jobs. I learned more about the etiology of yellow fever and, over some months, wrote my first conference paper on the virus's impacts on warfare in the Caribbean, delivered (shakily) to an audience in Tuscaloosa, Alabama. Eventually, my luck changed in the job market and I began to teach European, Russian, and German history, which carried my mind far from the Caribbean. I gave yellow fever no more thought for three or more years.