After government felling of large stands of native forest, yellow fever was isolated from a patient from Cumaca in the northern range in 1954.

Warnings were made that an epidemic was imminent and Dr. Wilbur Downs and Dr. A. E. (Ted) Hill, a specialist in tropical medicine, began a program of inoculating health workers and stockpiling vaccine.

Trinidad health authorities followed up with large-scale vaccination and intensive anti-aegypti measures including public education, regular inspection for breeding sites, and spraying of domestic residences with DDT.

In spite of these measures, and the fact that an estimated 80% of the population of Port of Spain were immune to yellow fever and dengue, several more cases were soon reported.

An attempt was made to totally quarantine the island just before Christmas, 1954, but the disease spread to the nearby mainland of Venezuela and, from there, all the way to southern Mexico, probably killing several thousand people in the process.