Not true.
At least one of my boas was a carrier for 6+ years. I have a large collection of animals including many colubrids and 3 womas, a pair of blackheads, a pair of stimsons, a pair of spotteds, a pair of childrens and a pair of anthills. None of them ever came down with the disease and it's been over a year since my boas were diagnosed and put down.
I am religious about cleaning - I even disinfect and/or change tongs between feedings and I never stick my fingers in waterbowls.
You have to be careful making blanket statements. There have been people who have IBD and have lost their entire collections. There have been some who haven't.
I went into my vet's office last year with a head full of preconcieved notions about IBD that I had gleaned off of the Net - most were variations on the same theme. Almost everything that is the conventional wisdom on this disease is just a bit off. It was only after talking to the lab where they looked for the inclusion bodies (and ultimately did the necropsies) and some of the researchers that I got a clearer understanding of what IBD is and how it can manifest itself.
I find it sad that both a veterinary manual and a quoted study list potential infection rates of between 33 to 50% and people poo-poo those numbers.
Again - I stress that Jacobson has been very reachable and has corresponded with some people on this forum. Instead of getting your knowledge from second hand sources (including me) talk to one of the foremost researchers of this disease and ask him your tough questions.