I found myself having a few more questions I wanted answered, so here's
a bit of what I found in case it interests others.  If time allows I want
to at some point read
animalscience.tamu.edu/ansc/publications/beefpubs/b6051-tuberculosis.pdf
and some others, and Shona may want to pursue things like
http://www.nal.usda.gov/awic/pubs/TB/WildlifeTB.htm
 
Here in the U.S. if bTB isn't spotted in more than one herd (any number
of animals in the herd it sounds like) in 4 years the state is deemed
"free" of it, but there are a number of wild vectors so every few years
it crops up in herds again and the state's classification is changed
once more.  The chances of truly eradicating it here are about like the
chances of eradicating yellow fever in South America where there are a
number of wild vectors -- pretty well zilch.
 
I think the reason people worry so much in NZ in relation to it is partly
due to a study from 12 years ago:
>Wild reservoirs of the organism exist in feral animals such as pigs,
>ferrets, cats, possums, and stoats, all of which are becoming
>increasingly suspected as a major source of M.  bovis.  While possums
>have long been realised as a source of infection, some attention has
>more recently been given to the importance of other feral animals as
>well.  In 1993; of those ferrets tested in South Canterbury around 70%
>were clinically infected (6), which yields support to this theory.  At
>present, possums are still incriminated as the major TB reservoir, yet
>the spread of TB from the possum to either the deer or to cattle has
>not been proven and is largely deduced from epidemiological studies
>and strain typing.
 
Dogs and cats can get bTB as well, BTW.
 
http://ivabs.massey.ac.nz/MUVSA/ass/micro/tb.htm
which is the source of the above quote also says:
>Less than a decade and a half ago it was widely believed that Tb was
>a spent force in NZ farming.  Compulsory testing of beef cattle began
>in 1971 with 0.8% positive reactors; by 1981 the prevalence had fallen
>to 0.1%...
>
> In deer the first diagnosis of M. bovis  infection in New Zealand was
>in wild animals in 1970, and by 1985 movement restrictions were being
>imposed on infected herds
 
It would be good to better know which of such animals are reservoirs that
can infect other species in turn (vector animals) or which of the species
are dead-end species for the infection.  I suspect that info is likely
out there but I don't have time to look.
 
Anyway, it is rare here but is a death sentence and it reads in multiple
resources like it has sporadic increases in prevalence within any state,
and --yes -- pathologists DO still test animals for it.  We had a ferret
tested in the early discovery of the current mystery disease.  Luckily,
it wasn't bTB, or any TB for that matter.  (Sadly, there is still not an
answer for the mystery disease so it is good that it is so rare, and that
two teams are working on it using different angles since no one knows
what will work and that one of those investigators said she is thinking
of bringing in a vet epidemiologist in case the unusual pattern may have
useful info.) (BTW, the most common TB seen in pet ferrets here is the
avian kind which is omnipresent in wild birds in the U.S.  and then it is
usually only already ill, immune-compromised ferrets who get it and even
for them it is not usual.)  Luckily, bTB is usually avoidable.
 
People make their own dietary choices for their ferrets and the whole
point of the post is that there is no reason for anyone who is feeding
a diet that isn't so poor that it is a known cause of illness to feel
guilty.  Each of the decent choices now in use has both upsides and
downsides, but there isn't enough data to accurately access and compare
them.  No amount of griping or arguing will change that; only careful
scientific research and funding research will.  To understand why we are
all stuck waiting here again is Richard Feynman: "It doesn't matter how
beautiful your theory is, it doesn't matter how smart you are.  If it
doesn't agree with experiment, it's wrong."
 
--Sukie
http://info.med.yale.edu/yarc/vcs/drugs.htm (drug dosings including for
ferrets for a number of meds, but last updated 5 years ago)
[Posted in FML issue 4780]