G. Armauer (Gerhard Armauer) Hansen

Born in Bergen, Norway, in 1841, Gerhard Henrik Armauer Hansen studied medicine in Christiania (now Oslo) and went on to work with patients affected by leprosy in western Norway. At a time when the disease was still poorly understood, he devoted much of his career to careful clinical observation and research.

In 1873, Hansen identified the microorganism now known as Mycobacterium leprae, linking leprosy to a specific infectious cause. The discovery was a major turning point in medical history and is often described as the first clear demonstration that bacteria could cause chronic disease in humans.

Hansen continued his medical and scientific work in Norway for decades and became an important figure in public health as well as bacteriology. He died in 1912, but his name remains closely tied to one of the most important breakthroughs in the study of infectious disease.