I worked with a woman who had been posted to the oil fields in Venezuela for a couple of years. After rotating Stateside, she eventually developed a severe recurring fever that left her debilitated for months on end, Doctor after doctor, test after test, no resolution. Eventually she ended up at a practice with a new physician who had trained in Cuba. He listened to her symptoms, thought for a bit, and asked if she had traveled in tropical Latin America. When he heard the connection to Venezuela, he responded, "Oh, yeah, you have..." and named some tropical disease that I have forgotten. Cleared it up in a few months.