Alphonse Laveran

Following his father into military medicine, Laveran served in the Franco-Prussian War before being stationed at the military hospital in Constantine, Algeria in 1878 to investigate malaria fevers afflicting soldiers.

On November 6, 1880, examining unstained fresh blood from a feverish soldier under a crude 400x microscope, Laveran observed pigmented crescent-shaped bodies suddenly erupt with lashing flagella—the living malaria parasite. This was the first time a protozoan, rather than a bacterium, was proved to cause infectious disease in humans. He later founded the Laboratory of Tropical Diseases at the Pasteur Institute.