Within a decade of Perkin's discovery of aniline Mauve, chemical dye production was in full swing and histoligists were using artificial dyes to stain samples. Although at the start of the nineteenth century doctors and scientists had no idea that bacteria caused illness, by the end of the 19th century researchers like Robert Koch were combining the work of Louis Pasteur and the work of William Perkin. Koch used synthetic dyes to stain and to see (under a microscope) previously invisible unknown germs and identified the germs for anthrax, tuberculosis, and cholera.
Another scientist, Gerhard Domagk, worked with coal tar dyes to create a pill which when swallowed would kill specific bacteria. Domagk discovered that the red dye Prontosil was effective against blood poisoning (Streptoccus) in mice. When his daughter developed blood poisoning Domagk gave her the treatment, as yet untested on humans. She recovered -- although her skin also turned an odd shade of red for a time. Domagk had based his experiments on the work of German bacteriologist Paul Ehrlich, who pioneered the "magic bullet" ideas of medicine now used in chemotherapy treatments.
Today synthetic (aniline) dyes still play a critical role in the discovery of new treatments and scientific discovery. The mapping of the human genome would have been inconceivable without colorfast synthetic dye. Modern medicine has brought Perkin's research full circle. Mauve, discovered in his search for an artificial quinine, opened the door to artificial dyes now employed in medical research on the malaria vaccine.