If you don't have pigeon Flys your pigeons most likely don't have (Haemoproteus Columbae)
Most pigeon Keepers are under the impression that mosquitoes are the main cause for spreading the diseases.
This may surprise you but it has been shown that the blood of the mosquito destroys the organism.
Another interesting thing to note is the disease is pretty much confined to pigeons.
This brings us to the pigeon fly ((Pseudolynchia Maura). As turns out this fly seems to only attack pigeons for the most part and is the main cause of the disease spreading.
Your main concern should be to prevent the fly from entering your loft and breaking its life cycle if it should enter.
one drug to treat this disease is Atabrine