In the early days, it was extremely hard to diagnose because it mimicks so many other diseases such as undulant fever. I almost had to force a doector to treat me for it. When my son caught it, it was diagnosed immediately and he recovered quickly.
It is some bad stuff and can be fatal. Reoccurrences are common if not treated corredtly the first time. As I understandit, today there are a few different strains and not all will test positive in the common tests.