While working the lab during his masters program Jim was poked through his glove with a needle. The contents of the syringe did not carry any horrible disease or blood or anything(or so they assured him) that could hurt him. But he because obsessed. Focused on illnesses so rare, so localized he could not possible have them. He made them run tests, tracked symptoms and eventually dropped out of the biology program. If he was going to die from some undetectable disease he was going to do on his terms.
He grew a beard and let his hair get long. Went weeks without leaving his small apartment. His friends, once concerned became distant. No one wanted to hear about rare and fatal diseases all the time and Jim figured it was better that way...since he was a goner anyway.