Daniel Cornelius Danielssen (1815-1894) was a Norwegian physician known as an early authority on leprosy. With C.W. Boeck, he was the author of the influential study Om Spedalskhed.

Danielssen was born in Bergen, and contracted tuberculosis at the age of thirteen; the infection continued to affect his health throughout his life. He earned his qualifications at Christiania University (now University of Oslo) in 1838, and returned to Bergen, which had a high concentration of leprosy patients; he helped to organise the town’s leprosy care program, and was made head of staff at the Lungegaarden leprosarium when it opened in 1849. In 1847, Danielssen and C.W. Boeck together published two influential early works on leprosy: Om Spedalskhed and Atlas Colorié de Spedalskhed. These remained standard reference texts on leprosy until Danielssen’s death.

Danielssen sought to understand the cause of leprosy; he held the firm belief that the disease was hereditary, and not infectious. To prove this point, he repeatedly attempted to inoculate himself and other hospital staff with leprosy, but he was not successful in transmitting the disease.

Gerhard Armauer Hansen, Danielssen’s protégé and eventual son-in-law, who worked alongside Danielssen from 1868, held the opposing view: he was convinced that leprosy was an infectious disease carried by microorganisms. It was reported that this disagreement often caused conflict between the two. Hansen would eventually discover Mycobacterium leprae, the causative agent of the disease, but Danielssen still refused to accept the bacillus as the cause.

Outside of his leprosy research, Danielssen also made contributions to zoology, served as chairman of the Bergen Museum, and was a representative of Bergen to the Norwegian Parliament for many years. He married Berthe Marie Olsen in 1839, and the couple had four daughters and a son, but his wife and daughters all died of tuberculosis. A form of leprosy, Danielssen-Boeck disease, is named in his honour.

Sources:

"Daniel Cornelius Danielssen 1815-1894". International Journal of Leprosy, Centennial Festskrift edition, Vol 41, No 2. 1973. 152-3.

"Daniel Cornelius Danielssen". Whonamedit?. Online. Accessed 17 December 2015.