Ok...I read this....put my hair up and got my books out. I am taking this info from Understanding Reptile Parasite by Roger Klingeberg DVM. I might suggest picking it up as I am not going to write everything but ...will kind of phrase some things up.
In the book it states that you should do at least 3 tests that are acid smeared fecal tests. Anything that eats mice could give you a false positive. It also states that you need to feed the snake before the testing. Also they stated that you can also do a tube feeding to be sure so that again the mice do not cause a false positive.
Now...for the cure....as your vet stated there is no known cure...at least not the time that this book was written. However it did state that they can try HBC which is Hyperimmune Bovine Colostrum. That there might be some cross reactivity of the antibodies to the reptiles. This was tried on 4 different monitors and 2 of the four tested clean after they did this. Now also in 2004 they were trying a different med...not sure if it was approved or not.
You can call my vet Dr. Jarchow at (520)877-2626 and leave a message I am sure he would call you back. He is one of the top 5 reptile vets in the world. I would think he would know all of the cutting edge meds out there and just might be able to help.