Q: "Bob!  At the Ferrets 2000 offical pub, you mentioned you thought the
next big plague to hit ferrets would be Aleutians Disease.  The very next
day, I heard Dr. Williams speak about it and I am now quite scared.  Is
it as bad as you think?"
 
A: I think therefore I am, and I am convinced it is the ferret's version
of AIDS.
 
I cannot and will not address the veterinary aspect of this question
because a) I am not well read on this disease, and b) I am not qualified
because I am not a vet.  But I have extensively studied the effects of
introduced disease into virgin animal populations, giving several papers
and recently being asked to write a book chapter on the subject.  So, from
an evolutionary aspect, I think I can discuss a few things.  Still, I will
forward a copy of this reply to Dr. Williams in the hope he can better
address the issue.  If I were you (assuming he elects to reply), I would
listen carefully to him and treat it as gospel.  That is not just because
the man in extremely intelligent, but also because he is an excellent
pathologist and probably knows this subject better than most vets (I know
he seriously impressed me, and I --for one-- am EXTREMELY pleased he has
started posting so frequently on the FML!!!  We are extremely fortunate!)
 
ADV (or Aleutian Disease Virus; aka Aleutian Island Disease) is a
parvovirus which evolved in mink (Mustela vison), and to which they have
more or less adapted.  By this I mean the disease is not always fatal;
some cases are very mild, some are deadly, but most are in that region of
middle ground where it can become a serious problem if the mink is weak
or stressed, but not usually fatal.  This is a coevolutionary adaptation
between the pathogen (the ADV virus) and the host (the mink); those strains
of the virus which are especially nasty kill off the hosts and reduce their
chances of being spread.  Those mink who are more resistant to the disease
survive and pass on the immunity to their offspring.  The end result is,
over a remarkably short number of generations, the disease becomes less
deadly and the hosts become more resistant.  Take measles for example; it
is a mutated variant of the same type of virus which causes both rinderpest
and canine distemper.  When it first spread in Europe, people died by the
thousands.  Over a few generations, it became a serious, yet not
necessarily deadly disease.  Until Europeans floated to the New World,
and found a virgin population; that is, a population never exposed to the
disease.  Tens of thousands of Native Americans were doomed.  Now days, few
people, including Native Americans, die from measles.  Coevolution between
host and disease has taken place; evolution in our time.
 
Mink and ferrets are kissing cousins in Weasel World.  Because some fur
ranches housed both ferrets AND mink, it was just a matter of time for a
chance mutation to allow the virus to cross the species line.  Like in the
measles example, the disease is usually quite nasty in a virgin population
(ferrets) and ultimately results in death.  But that's not the problem as
I see it.  To me, ADV is very much like AIDS in that
 
1) it has a very long incubation period before it is expressed,
2) in ferrets, it is almost always fatal,
3) casual contact can spread the disease,  [huh, is that a typo?  BIG]
4) as viruses go, it is not especially hardy,
5) they are both immune system diseases and
6) there is NO cure.
 
The first reason is really the one which scares the crap out of me.  Unlike
ECE, where the ferret contracted the disease rapidly after exposure, it can
take years for ADV to be expressed, and by the time you realize your little
bundle of dancing fur is sick, your entire house could have contracted the
disease, dooming all.
 
The other thing about ADV which scares me is when the symptoms start being
expressed, they can easily be misdiagnosed as a non-specific wasting
disease, insulinoma, cardiomyopathy, renal disease and a host of other
deadly things.  It is possible many cases of ADV have been (and will be)
misdiagnosed, and animals which are spreading the disease are still coming
into contact with healthy ferrets.  So, like when AIDS first hit in the
USA, it can take a long time for the full extent of the disease to be
known.
 
ADV, like the initial cases of ECE, is already spreading into the
ferret population like a virgin ground disease.  The effects are easily
predictable; at first the disease will kill a tremendous number of ferrets,
but ultimately, it will either burn itself out (doubtful) or both the
disease and ferrets will coadapt.  These are predictable results, but
the problem is the large number of ferrets which will die before the
predictions hold true.  I don't want my guys to be a part of that
statistic.
 
This may sound a bit like hyperbole, and perhaps it is; as I said, I am
not a vet.  However, if I am correct and this disease follows the same
sort of pattern as any number of virgin ground diseases, including plague,
distemper, ECE, AIDS, measles, smallpox, and many, many others, then you
can expect that what you observed with ECE will also occur with ADV.  I
think it will be the next ferret plague, and in years to come, thousands of
ferrets will be suffering as a result.  I am sure Dr. Williams can easily
explain this better than I, and fervently beg him to do so, perhaps also
offering public heath advice in preventing exposure.
 
Bob C and 15 Mo' Virgin Ground Ferrets
[Posted in FML issue 3185]