Boa constrictors can be asymptomatic carriers of Inclusion Body Disease. They may also be symptomatic carriers. It takes quite some time for symptoms to present themselves. Retained sheds, regurgitation, and Respiratory infection are common precursors to
IBD. Unfortunately, there is very little known regarding how it is transmitted. Kaplan's article is not bad, despite the fact that she hates herpers. But it is the same information that is regurgitated all over the internet.
I am pleased to say that there are finally methods to test for
IBD on living snakes. Of course, none are as simple as a blood test. They can do a dermal, gastric, or liver biopsy to test for Inclusion Bodies. These are not cheap and are generally invasive (aside from the dermal test).
I, personally, believe that
IBD is much more prevalent than people think. How many keepers get pathology reports on every snake that dies?
I would say that
IBD is something to be cautious about, but not paranoid of. Good quarantine procedures are a must and also good husbandry with a focus of eliminating cross-contamination. My guess is that the most prevalent way that
IBD spreads is through feeders. A rat is dangled in front of a boa's mouth or danced around the cage, but the snake doesn't eat it. So that rat is moved on to the next snake. Cost efficient for feeders, but offers a great risk of cross-contamination. I have one feeder per cage, if it is not eaten, then it gets tossed.
Of course, with my current situation, I think my husbandry will border on paranoid for quite some time. I wear Nitrile gloves when working with ANYTHING. Gloves are changed between cages. Tongs are sterilized between animals during feeding. High risk animals have their own equipment and water storage. This gets quite time consuming with 60-70 animals.