Sometimes the "sneezing" is really them trying to cough up the worms, as they will fill the thoat of the bird and if one has it, they all do. I just treated mine for it and they seem MUCH better and no more gaping, and they are gaining weight again...I never saw any of mine cough/sneeze, but one was "gaping" a lot, and kinda lethargic...I treated with the safeguard liquid goat wormer, 3 ml for two days, then will retreat in 10 days also.
Not sure what I am going to do about their run...read an old article that said salt will kill the earthworm, and the gapeworm all the way down to the eggs, but probably won't be able to grow anything in the run, if I salt it.
I should clean their coop, each time I treat them, but only have enough for one deep cleaning, as I just deep cleaned a bit ago for cocci...so am going to have to wait till the second dose to deep clean the coop and hope and pray they don't get reinfected. I did let them out into the run, but am keeping their food and water, in the coop now...keeps it cleaner and won't get contaminated.
http://www.archive.org/stream/gapewormoffowlss00walkrich/gapewormoffowlss00walkrich_djvu.txt
here is the article I ran across, when researching this...you have to scroll down quite a ways to get to the actual article and for treating the ground, it is at the every end of the article. Sounds like it is possible to rid the run of gapeworm with salt and a few other things, but seems salt is the best...I live on a mountain, so am hoping, treating the run, when I do their last treatment, will run off and the land won't be totally sterile????
I still haven't found out if I retreat 10 days from the start of the wormer, or 10 days from end of two day treatment. But it did work on mine. I was unsure, but figured, if it was the gapes, best to treat, than to lose some...I treated them all. I am also a bit worried, letting them out in the run too....but I hated keeping them in the coop, although they did do better kept inside during the treatment.
Poor things are now confused, though, as I used putting their food and water back in the coop, as a sign it was time for bed...now they don't know whether to go out, or stay in!
Best of luck with yours!!!
edited to add, oopps sorry, 3 ml per gallon of water.