You will be given a definition of a task first, then some input of the task.
Generate a question which can yield the answer mentioned in the input. Generated question must be answered by the answer provided in input, without using any extra knowledge.

Context : François Huber was only fifteen years old when he began to suffer from a disease which gradually resulted in total blindness; but, with the aid of his wife, Marie Aimée Lullin, and of his servant, François Burnens, he was able to carry out investigations that laid the foundations of a scientific knowledge of the life history of the honey bee. 
Answer : blindness
Output:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
What was the sickness that killed François Huber?