Coronaviruses are very much NOT prone to having variations in
themselves (though the symptoms can vary among animals, of course).
Yes, you could be seeing true ECE, but you may not be. This past post
will help you. Dr. Bruce Williams is the original finder of the corona
virus cause of ECE. Dr. Matti Kiupel did the later independent work
confirmation (in communication with Dr. Williams), and Dr. Kiupel's
Lab in Michigan State has patented the genetic code of ECE which they
have since uncovered after many years of work.

http://ferrethealth.org/archive/SG6289

>Actually, coronaviruses aren't know for their predilection to mutate,
>such as we see with influenza viruses (of a different family, the
>Pramyxoviridae). There are many variables that determine whether a
>particular animal will become clinically ill, subclinically infected,
>or fight off infection. Age, previous infection, maternal antibody,
>and concurrent disease are some of them.
>
>It is well known that young animals are rarely clinically infected with
>the coronavirus that causes ECE, but can be carriers for up to 6-8
>months. Coronaviruses appear to infect more readily in animals with a
>higher gastric pH, and the prevlaence of H. mustelae infection in older
>ferrets supports the higher frequency of clinical infection in this
>demographic. Additionally, many kits have maternal antibody, as quite
>a few breeders have endemic ongoing infections (facilities in which
>clinical animals become extremely rare over time.) So it is of no
>surprise that the young animal is perfectly fine while the three older
>ferrets are experiencing ECE firsthand.
>
>Currently, there appear to be a number of ongoing ECE outbreaks, far
>more than we have seen in recent years. It is likley that this may
>become the status quo - seeing hotbeds of infection every couple of
>yers as immunity in the animals of a particular area begins to wane.
>
>With kindest regards,
>
>Bruce Williams, DVM

What IS new in the U.S. (and older in Europe) is an FIP-like corona
virus in ferrets. It behaves like the "dry form" of Feline Infectious
Peritonitis". Luckily, it is very rare. See:
http://ferrethealth.org/archive/YPG662
http://ferrethealth.org/archive/YPG303

What also has been seen increasingly in the U.S. is a genus of one
of multiple types of coccidia that ferrets can get becoming more
prevalent, but many hospitals only look for species within Isospora
whereas one genus one often found in ferrets is Eimeria. Eimeria
furonis is more prone to causing fatal cases of coccidia and has killed
a number of shelter ferrets in certain parts of the U.S. within the
last 12 to 18 months. Shelters especially have to be aware of the
possibility of this disease since the numbers of ferrets increase the
infection risk. Everyone should know about it, though. Dr. Matti Kiupel
did a lot of recent work on that. BTW, you can find an earlier list of
the coccidia types which were then documented as occurring in ferrets
here:
http://ferrethealth.org/archive/SG17961
gleaned from
http://biology.unm.edu/biology/coccidia/carniv2.html

Furthermore, possibly increasing in prevalence or simply is recognition
are some forms of mycobacteria of which ferrets get multiple species.
(See archives.) Mycobacteria can be harder to test for but is luckily
seen less often.

There are MANY causes of intestinal infection from giardia (from ponds,
aquaria, etc) to some of the mycobacteria including the avian form
thought to be increasing the carnivore pet population in some states
so listed as an emerging disease by some states (from raw poultry or
in immune-compromised ferrets from bird waste on shoes when one comes
inside) to coccidia to ECE to E. coli infection, to salmonella, to...

I wanted to get past some of the most severe ones up-front in case
things worsen so you have some directions in which to jump for testing.
I am sure that others will jump in with some further serious and less
serious infectious causes because I know this post is incomplete. They
might (I don't clearly recall off-hand if some of these cause matching
symptoms.) go into diseases like Clostridium perfringens, Type A;
Campylobacteriosis; Helicobacter; Chlamydia; Cryptosporisiosis;
Helminths; and very possibly others.

Sukie (not a vet)

Recommended ferret health links:
http://pets.groups.yahoo.com/group/ferrethealth/
http://ferrethealth.org/archive/
http://www.afip.org/ferrets/index.html
http://www.miamiferret.org/fhc/
http://www.ferretcongress.org/
http://www.trifl.org/index.shtml
http://homepage.mac.com/sukie/sukiesferretlinks.html

[Posted in FML 5642]