[2] He was the first head of the Department of Bacteriology and Preventive Medicine at the University of Texas Medical Branch.

[2][4] Boyd became a staff member of the International Health Board of the Rockefeller Foundation in 1921,[5] remaining with that institution until his retirement in 1947.

He directed the International Health Board study of the epidemiology of malaria in the state of Rio de Janeiro, Brazil from 1922 to 1925.

[6] Returning to the United States, he served as director of the Rockefeller Foundations's malaria field study stations in Leesburg, Georgia and Edenton, North Carolina.

[7][1] Boyd was an advisor and consultant on malaria to the Tennessee Valley Authority, the Pan American Sanitary Bureau, the League of Nations, and the United States Army.

He attended international conferences as a delegate for the United States, and served on national boards related to tropical diseases.