There are different forms of trout fever. There's the very sudden, acute version I just described. Then there's the more chronic version which can take over your life. Chronic trout fever creeps into your daily life at times when you should be focused on something else. A symptom of chronic trout fever would be not hearing what someone is saying to you when away from the stream, because in your mind your thinking about fly fishing. You might even give a one sylabol response to a question you've been asked & then move your arm through a casting motion (air casting), while not making direct eye contact with the person speaking to you. The sevarity of your condition can be judged by the situations in which your mind wonders back to the stream when you should be paying attention to what's going on around you (it's really bad if you do this while speaking to any authority figure).
All of us, from time to time, will suffer from some form of trout fever. It is a consequence of fly fishing, maybe it's a side effect, I can't be sure. There is no real cure for trout fever. You can, however, releve the afliction by going fly fishing. The better day you have along the stream & the more fish that you catch will extend the time that your symptoms are supressed. If you can't get to a stream to fly fish, a substitue treatment would include tying your favorite flies &/or reading a good fly fishing book.