Top left hand corner, Walter Reed, top right hand corner, Aristedes Agramonte, bottom left, Jesse Lazear, bottom right, James Carroll. Walter Reed, (1851-1902) was a U.S. Army physician who in 1900 led the team that postulated and confirmed the theory that yellow fever is transmitted by a particular mosquito species, rather than by direct contact. This insight gave impetus to the new fields of epidemiology and biomedicine, and most immediately allowed the resumption and completion of work on the Panama Canal (1904-1914) by the United States. Aristides Agramonte y Simoni (1868-1931) was an American physician, pathologist and bacteriologist with expertise in tropical medicine. Jesse William Lazear (1866-1900) was an American physician. Major James Carroll (854-1907) was a US Army physician. He and Lazear, subjected themselves to the bite of infectious mosquitoes, to test the theory that mosquitoes were carriers of yellow fever. The infection he contracted eventually killed him.