Bernhard Riemann, one of the most influential mathematicians in history, died at the young age of 39 from tuberculosis. In 1866 Germany/Italy, how common was it for a relatively young man, of at least decent socioeconomic standing to catch tuberculosis? I had imagined the disease not being as rampant by that point in history, but may be mistaken. Also, once caught in a circumstance such as this one, how common was death in the next year or two?
I just learned that Riemann died at such a young age while doing some reading on him, and am shocked. He accomplished so much for the field of mathematics, we can only imagine what other advancements he may have made. An anecdote, immediately following his death, from his wikipedia page sums up that sentiment:
"Meanwhile, in Göttingen his housekeeper discarded some of the papers in his office, including much unpublished work. Riemann refused to publish incomplete work and some deep insights may have been lost forever."
(This is my first /r/AskHistorians post, so I'm sorry if anything is presented incorrectly. Thanks a lot!)
I am not a historian but an epidemiologist interested in history and normally I only read this subreddit, but in this particular case I feel confident in trying to answer your question:
Your assumption that tuberculosis was rare at the time is not correct. In fact, in the 1830s and 40s an epdemic swept through Europe with death rates going up to 1 in 100 (source). Given that in modern times only 1 in 10 infected people will die of the disease it is reasonable to assume that the rate of latent infections was a significant proportion of the total European population. So no, it was not "a freakish accident", it was as about as probable as catching a cold nowadays.
And it is very unlikely that Riemann got infected only shortly before his death. Tuberculosis is a disease with slow progression and long latent phases where the pathogen can be contained by the immune system. Modern data shows that most infected but otherwise healthy people can contain the infection for an average of 10 years before the containment is overcome by the disease and active or "open" TB develops.