In 1956 and 1957, several U.S. Army biological warfare experiments were conducted in Avon Park. In the experiments, Army bio-warfare researchers released millions of mosquitoes on the town, in order to see if the insects would spread yellow fever and dengue fever. Hundreds of residents contracted a wide array of illnesses, including fevers, respiratory problems, stillbirths, encephalitis, and typhoid. Army researchers pretended to be public health workers, so that they could photograph and perform medical tests on the victims. Several people died as a result of the experiments.