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From:
"JEFF JOHNSTON, EPIDEMIOLOGY" <[log in to unmask]>
Date:
Thu, 18 Jul 1996 14:49:51 -0400
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I'll add my concerns to those of Bruce Levine, TLE, Roger McMillan and
others regarding the deliberate exposure of ferrets to suspected ECE.  One
of the greatest problems with ECE is that the virus has not been well
identified yet, and so there is no definitive way to say that one ferret
currently has it, had it previously but recovered, is a carrier of the virus
but is unaffected or has never been infected.  Each of those scenarios might
prompt the use of different precautions.  I suspect that some of the
existing genetic viral tests could determine whether ECE is really a
coronavirus and be used as a diagnostic but it will be a few years before
these are affordable.  (Hoffmann-La Roche has a commercial genetics lab here
in North Carolina that charges as much as $700 for [human] paternity
testing.)
 
So, there are ferrets out there with infectious diarrhea, some of which is
ECE, probably causes by a coronavirus.  BUT...not all diarrhea in ferrets is
caused by ECE.  It may be caused by many other viruses, by bacteria, such as
the one that causes cholera in humans and pigs, by various parasites, by
toxins or GI irritants, by stress or by diet changes.  (The last three
causes could appear to be contagious depending on the circumstances.)
 
Pam Grant's observation may be correct.  Indeed, her experiences suggest
that the infection she has dealt with is easily tolerated by young ferrets.
This is true of a number of human diseases, such as chickenpox, mumps, and
polio, which have mild or no symptoms in infants or children but can be much
more serious or even fatal in adults.  Unfortunately, most of us have been
using the term "ECE" to describe any infectious diarrhea, some of which
*may* be caused by other pathogens.  Other pathogens may react differently
from the infection Pam has experienced.  If, for example, an infection is
equally hazardous to ferrets of any age, then exposing a young ferret to
what is thought to be "ECE" could be disastrous.  The bottom line is that we
need a simple and relatively inexpensive way to diagnose or exclude *real*
ECE.  (That would also help us to verify how long ferrets shed the virus and
whether they can become carriers.) Until such a test is developed, I would
advocate caution in exposing kits to an infectious diarhhea unless you KNOW
from experience that it is innocuous in kits.  The "ECE" in your household
may not be the same "ECE" Pam has dealt with.
 
BTW, TLE asked about species specificity of coronavirus.  A researcher at
the University of North Carolina, where I'm at, has shown that coronavirus
can jump species--from a mouse to a hamster in this case.  This is a jump
from one species to another within the same family.  Theoretically, then, a
coronavirus from dogs could jump to ferrets, although this is a bigger
"leap" for the virus to make as ferrets and dogs are in the same order
(carnivores) but in different families.  Such cross-species jumps do happen,
however.  Sometimes it's a matter of getting a big enough dose to be
infected as was the case with the Hanta ("four-corners") virus three years
ago which crossed from mice to humans across two different orders (rodent to
primate).
 
Species specificity is mostly associated with the "docking site" the virus
uses to get into cells in the body.  Without knowing exactly what "ECE" is,
it's impossible to speculate whether it is likely to be able to jump species.
 
   --Jeff Johnston ([log in to unmask])
[Posted in FML issue 1635]

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