Red Tail Boa and IBD and transmission to BP's

[Eventide]

From the same paper linked (re: liver biopsies):

"The disease affects all organ systems and the inclusions
can be found in virtually all cell types. The epithelia of
the liver, pancreatic gland, kidneys and gastric mucosa contain
the highest density of affected cells (Garner and
Raymond 2004).

"The best way to achieve diagnosis in a living snake is to
perform a wedge biopsy of the liver through a flank incision.
A biopsy of the tonsils on the surface of the oesophagus or
a biopsy of the gastric mucosa is also an option, but requires
an endoscope suitable for the size of the snake (Garner and
Raymond 2004; E. R. Jacobson, personal communication).
Skin biopsies are another possibility, but are not as sensitive
as a liver biopsy. However, the sensitivity can be
improved by taking several skin biopsies (Garner and
Raymond 2004)."

Granted, this doesn't say at what stage of the illness it affects nearly all cell types; however, it does seem, from the reading, that it doesn't take long.

About the statistics on how many boas have the disease: Given what others mentioned about the frequency of affected snakes given biopsies (even less common than those that get taken to the vet), 33% is going to be an upper limit, at best.

EDIT: Please note I'm not saying liver biopsies are 100% accurate all the time.