As horrible as it sounds, if this boa is asymptomatic, there is no way of knowing if the snake has IBD.

If you are seriously concerned for your collection (and who wouldn't be), what you could do is always take the least valuable/favorite snake from your BP collection and house it in the same room with your boa. I have heard of keepers before using Normal BPs as 'canaries in the coal mine' type thing. They will house a BP with the boas to try and catch an infection, even if it's asymptomatic.

You could always do that and have a single BP exposed and then continue to keep them together for a time (not in the same enclosure, of course). That way you would feel more comfortable about moving the boa into your main collection if you felt so inclined.

And, if in the rare chance it is possible, you have not risked your entire collection.

But it's not foolproof. If they're in the same house, there is still that risk.