 Koch and his relationship to Paul Ehrlich, who developed a mechanism to diagnose TB, were portrayed in the 1940 movie "Dr. Ehrlich's Magic Bullet".Koch next turned his attention to cholera, and began to conduct research in Egypt in the hopes of isolating the causative agent of the disease.However, he was not able to complete the task before the epidemic in Egypt ended, and, after a short trip to Persia, traveled to India to continue with the study.