If you want to be successful, study successful people and do what they do.
"The infected larvae are usually seen in the capped stage, but it is common for unsealed larvae to show signs too, where they can lose their segmentation, shape and colour. They can look so much like EFB that on one occasion I was convinced I had EFB, so I called out the Bee Inspector who took one look at it and said "Yes EFB, I'm afraid". To the surprise of both of us the LFD (lateral flow device) test was negative, so we thought the test kit was faulty and used another one, that was also negative. The danger here of course is that someone who is trained to concentrate on nothing but disease and a very experienced beekeeper were both fooled. A less experienced beekeeper may think the next time they see the same symptons it is chalk brood, when it may be EFB."
Randy Oliver comparing EFB and AFB;
"Practical application: Some of these symptoms can be confused with those of AFB—I was surprised when I sent a very similar-looking sample to the lab last season and it came back positive for AFB!"
Importance of a lab test.
CB seems to reduce as spring moves along so maybe adding a banana and seeing an improvement might just be a coincidence. One bad case I had was cured by replacing the queen. However the queen was put in another hive and the CB went with her which would indicate a genetic component or a deficiency in the queen. I beleive that the spores can last for 2 - 3 years though.
I have one noticeable CB colony now; I will probably leave it for the time-being and see what happens. Maybe I will raid the fruit-bowl!
May your bees read the same books as you do