<font color="blue"> histoplasmosis </font>
Bird droppings are a source of that, too. I had a friend who's father had a job as a warehouse maintenance worker. One of his jobs was to clean the pigeon poop from the rafters in the factory. He died from complications related to histoplasmosis. Very nasty disease.
The bats can get in through the tiniest openings. I'm at a loss as to any more suggestions. Seems you've covered most of them. Netting will catch them if you want to trap them, but as soon as you take them outside, they'll come back in. Have you found anywhere that they can come in? Someone suggested the bat door, that you put in where they go in and out. It lets them out, but they can't get back in. As I recall it's like a cloth sleeve or something that tapers to a very narrow opening. Man, what a problem. Is this the first year you have had trouble with them in that barn?