Hi Murgie, Aspegillis is a fungus. My daughter (16yrs) grew it two years ago. It's kind of complicated to explain but i will try. Apparently it is not uncommon to find in CF patients. It seems the problem comes when the patient has an allergic reaction to it. We too wondered where it came from. We lived in Germany for three and a half years and had just returned to the states when they found it. We'd been back about 5 months or so. First they said, we'll leave it alone and watch. Then a few months later they put her on Sporanox (they are capsules). She took that for about 6 months. About four months into taking the Sporanox they decided to get more aggressive and put her on Prednisone. We were very uneasy about long term steroid use. They said she would be on it for about 3 months, could be less. During the time when she would come off the prednisone we got a new assignment (military). They decided that they would let our new CF center decide if she was ready to go off. Happily they did. During this whole time they kept checking her levels of something. That was the confusing part. They'd explain it to me over and over again and finally I got it but not enough to repeat it. Right now her "levels" of what ever it is they look at are good. She's (knock on wood please!) not had any flare ups concerning her aspergillis. After we were told she had this fungus I did a search on Aspergillis. That is where I found that it was not uncommon in CF patients. I am surprised that your sons doctor did not explain it to you. Well at first they didn't to us either, come to think of it. Just that she grew a fungus and they were going to watch it first. I don't think that you have any control over the aspergillis environmentally anyway. I asked too, was it because it rains so much in Germany could that be where/when she got it. They said it was hard to say, it could have been there for a while and is (was) just now giving her problems or it could be something she got recently. Ask if they are going to do anything about it in your son. IS it something to worry about? They should have told you from the start. Unless, I guess, if you got the lab results over the phone and you haven't had an appt. yet. They told us at an appt. I never call for lab results because they call us if there is anything abnormal. I hope I've helped in some little way. This was just our story with Apergillis. Liza