Cold War tensions and the polio vaccine was the first polio vaccine to receive approval of the U.S. government, and was used until 1961 in America, when the Sabin vaccine was recommended to replace it. Albert Sabin, a virologist who publicly disagreed with Salk and his killed vaccine, worked on creating a vaccine with live, attenuated vaccines. Despite Cold War tensions, in January, 1956 Mikhail Chumakov, the director of Moscow's Polio Research Institute, his wife and colleague Marina Voroshilova, and Anatoli Smorodentsev, traveled to the U.S. in order to study the Salk vaccine and visited the laboratory of Albert Sabin. With the clearance of the FBI, Sabin
David Bruce (microbiologist) discouraged the experiments being carried by Zammit, and doubted his ability as a microbiologist. Eventually, when he learned of the positive results linking the fever with unpasteurized goat milk, Bruce tried to discredit the role of Zammit and take credit to himself. To a certain extent he succeeded, as it was renamed after him as brucellosis, however information about the role of Zammit has eventually surfaced. When he was transferred to South Africa, Bruce was sent to Zululand in 1894 to investigate the outbreak of cattle disease which the native called "nagana". In 1903, he identified the causative protozoan, and