Hi,
Thats the problem.
IBD can be symptomless in the boas for a long time and you think everything is fine and put them in the same area and all the BP's die in 3 weeks.
The chances are your boas do not have it at all but I would use one snake out of the collection as a canary - especially for those with big or expensive collections.
But since we know so little about IBD and how it can be transmitted I'm not sure what the current advice is.
dr del