I re read your post, and you are right. Boas can be healthy and be carriers of IBD. They can infect their partner and pass it on the their babies. If you have a clutch of babies that don't do well, that is when you test the parents. Live liver biopsies are not cheap but the peace of mind is priceless.
Dr Klinengerg developed a blood test for IBD. Sadly the drug companies said is was not profitable to produce it for commercial use. It does not give a definite no (it does not have it) but it will not give a false yes.