Discovery
During many of the severe, early Yellow Fever outbreaks people were blindly fighting a mysterious enemy. Quarantines and city-wide cleanups were attempted, but no one knew the cause of the disease or how it spread. Some believed it could be transmitted via contact with the bodily fluids of the ill, others were less confident though they had no solid theories themselves. One man, Dr. Carlos J. Finlay, was mocked by the scientific community for his theory that Yellow Fever was a pathogen transmitted by mosquitoes. Of course Finlay, like that guy who said doctors should use antiseptic hand-wash between performing autopsies and delivering babies, was absolutely right.
He wasn’t the only one to theorize that mosquitoes could transmit disease. In the late 1800’s, Ronald Ross and Patrick Manson demonstrated that mosquitoes were able to transmit malaria. But Finlay was unable to prove his theory to the satisfaction of his colleagues, and was ignored and insulted for decades. It wasn’t until he contacted Walter Reed of the U.S. Army Yellow Fever Board that his theory had the chance of being taken seriously. Although Reed (whom you might know better as a hospital) was not a strong supporter of Finlay’s theory, he at least thought it was worth looking into. After all, nobody else had any answers and with troops dying of the fever during the Spanish American War, he had his work cut out for him.
When a prisoner in Havana died of Yellow Fever, while his multiple cellmates were fine (besides, you know, being in prison) it gave more weight to the mosquito theory and Reed and his colleagues, James Carroll, Jesse Lazear, and Aristides Agramonte decided to design some experiments to get to the bottom of the issue. Of course, this being the 1800’s (when science a little less… organized), Carroll and Lazear did this by turning test tubes of Yellow-Fever-exposed mosquitoes over on their arms, which lead to Carroll becoming extremely ill, though he recovered (mostly), and to the death of Lazear. After that they (well, not Lazear) designed an experiment that involved putting volunteers in one of three different huts: a control (nothing interesting there), a poorly ventilated hut full of fomites (articles of clothing/bedsheets/etc that were covered in the blood and vomit of Yellow Fever victims), and a well-ventilated hut with 15 infected mosquitoes. Needless to say, the volunteer who slept in the mosquito hut was the only one to develop Yellow Fever.
Mosquito Control and Panama (Part 2)
Around the time of the discovery made by Reed and his crew, U.S. Army Captain William Gorgas implemented a strict mosquito control program that involved the destruction of larval habitats. He and his colleagues set out and covered all the stagnant bodies of water they could find with a layer of oil. They instructed homeowners to do the same or face a $10 fine. The program eventually led to the eradication of Yellow Fever from Havana.
Gorgas, who had been sick with Yellow Fever in the past and was immune to the disease, requested assignment in Panama during construction of the canal. While some were still reluctant to let go of previous theories, the ambitious and frustrated Theodore Roosevelt was supportive of Gorgas’ efforts and granted him extensive funding for mosquito eradication in Panama. For a while, mosquito control became the most important part of the canal project. Gorgas had thousands of workers at his disposal and this time it took more than some oil on water, because they were targeting more than just Aedes mosquitoes (malaria being another major problem for canal workers).
Control agents treated homes with pyrethrum, oiled standing water as they’d done in Cuba, and attached screens to all the windows. Due to these efforts, Yellow Fever was completely eradicated from Panama in 1906 and that (plus the control of malaria in the region) is almost certainly the reason the U.S. was able to finish the project.
Vector Adventures 