Dr. Alan Johnson said he volunteered in the Liberian capital of Liberia . He returned to the United States on August 25 . Questions about the Ebola outbreak . He was to be in Liberia for 21 days . Many American medical workers have been infected with Ebola in West Africa .
Dr. Alan Johnson said he volunteered in the Liberian capital of Liberia . He returned to the United States on August 25 . He was to be in Liberia for 21 days . Many American medical workers have been infected with Ebola in West Africa .