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| Sleeping sickness research |
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| Restless in Retirement: Journeys to the Tropics |
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In 1905, although officially retired, Koch returned to Africa. He continued his studies of East Coast fever, malaria and trypanosome diseases.
In 1906 and 1907 Koch carried out extensive research into sleeping sickness: in 1895 David Bruce had discovered that this condition was caused by a type of trypanosome and that it was transmitted by the tsetse fly. Koch studied the insect’s habitat. To combat the disease, he recommended the extermination of the flies by extensive deforestation and early treatment of the persons affected with atoxyl, an organic arsenic compound which was replaced by arsenic- and mercury-free chemotherapeutic agent Bayer 205 after World War I.
Koch’s work on sleeping sickness formed the basis of Paul Ehrlich’s research, particularly in the development of salvarsan for the treatment of syphilis.
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| Trypanosoma Gambiense, 100x, photo print, 1908. | Trypanosoma Gambiense, 100x, modern objective. |
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