Inoculation experiments on rabbits

At Lungegård Hospital, assistant physician Gerhard Armauer Hansen carried out a number of different experiments to find the cause of leprosy. He was eventually convinced that the disease was contagious and made many attempts to prove it. In 1880, he was convicted of inoculating leprous material onto a patient without her consent.

He also made several attempts to inoculate leprous material onto rabbits, to see if they would become infected. There are some small handwritten notes from a couple of such experiments with rabbits, and it is reasonable to assume that they are Armauer Hansen’s own notes. All the notes are probably from the same summer, 1871.

In the experiment in 1871, he used two adolescent reddish-brown rabbits, both of which were marked in the left ear. He placed a nodule from an eyelid under the skin in the area between the neck and the back. A month later, he could feel the nodule under the skin of one rabbit but not the other. After a couple of months, both rabbits were dead. ‘Neither of them showed anything abnormal’, he wrote, and he could not find any remnants of the nodules.

None of the rabbit experiments yielded any results. In the three-year report for the years 1868–70, Danielssen states that experiments had been carried out with rabbits, but that the results so far had been negative. Hansen stated the same in his report about the cause of the disease from 1874, where he describes that he had ‘inoculated a total of 12 rabbits with leprous products’, but had to conclude that none of the rabbits ‘became leprous’.

Notes, probably taken by Gerhard Armauer Hansen, describing two experiments in the summer of 1871, in which he tried to infect rabbits with leprosy to prove that leprosy was contagious.
From the archive of St. Jørgen’s Hospital, Bergen City Archives.

4/7 In one of the rabbits
the nodule underneath
the skin can be felt, in
the other not.


1 / 8 Both animals died.
Neither of them showed
anything abnormal, no
remnants of the nodules can be found.

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