I don't want to belabor the immunodeficiency virus issue and certainly don't
want to perpetuate any flames on the topic, but perhaps I can shed more
light than heat on the subject.  The basic nugget of information to remember
is that the immunodeficiency viruses caused by retroviruses (HIV, FIV, SIV,
etc.) are highly specific for a family of animals, or even for a specific
species.  Ferrets cannot be infected with HIV.  Ferrets and humans belong to
separate orders, i.e., carnivores and primates.  That's far too different a
gap in species for a retrovirus to cross over.  Similarly, FIV cannot be
passed from your cat to your ferret or to you.  Cats and ferrets are in the
same order but in different families and that's still too big a gap for that
kind of virus to bridge.  However, if you had an FIV-infected housecat and
also, say...a pet bobcat you might have some basis for worrying since
housecats and bobcats are members of the same family--Felines.  You'd also
have cause to question your sanity since the bobcat would tear your house
apart...but that's a different issue.  :) A retrovirus *might* be able to
cause infections in two members of the same family, but it's *still*
unlikely unless the two species are closely related.
 
It's confusing dealing with many different infectious agents, because the
rules are different for each.  Influenza can infect mammals and birds, and
some parasites have life cycles that include fish, snails, birds and mammals
so that virtually anything alive that walks, flies, slithers or swims is a
potential target for infection.  All you need to know about immunodeficiency
viruses is that they are *very* species selective.  Keep your FIV+ cats
isolated from uninfected cats, but your ferrets can interact with both
without getting the cat's infection or passing it along to the uninfected
cats.
 
--Jeff Johnston ([log in to unmask])
[Posted in FML issue 1831]