I've been distracted with other things for a few days, but want to redress
the rabies testing comments. On April 26, Ferret McDuff wrote:
>I am not confusing Jeff Johnston with "the enemy".  I am merely commenting
>that, as he freely admits, he speaks their language, including the many
>partial truths that are so convincingly used to mislead the unknowing
>public when it comes to ferrets, rabies, shedding studies and post exposure
>treatment.
 
An "admission" implies guilt.  Just because I can speak like other
professionals in my field I am not guilty of being as uninformed or mislead
as the worst members of the my profession.  On the issue of rabies tests:
 
>There are tests which detect the presence of rabies in saliva and spinal
>fluid which are currently at least as reliable as the immunofluorescence
>antibody testing.  These, however, are not the current standard and public
>health is slow to change to a new method over an old accepted one.
 
Yes, public health can be slow to change to new techniques or methods.
Immunofluorescence ("IF") has not been accepted as the definitive test.  At
the moment, it will not accepted as an alternative in all cases.  As we know
with ferrets, the virus is not always expressed in saliva.  To know whether
rabies has infected an animal that may not shed the virus in saliva, some
type of neural tissue must be sampled.  I've read studies that tested for
rabies using IF with neural tissue from skin biopsies.  If that could be
validated as a sensitive and specific test, it would be great, but health
officials would want to see those data since the rabies virus makes a
beeline for the brain once it gets into the body.  I'd wonder if rabies
could always be found in the fine network of neurons in the skin.  I'd also
like to see the data on how sensitive IF is for rabies in spinal fluid.
Same caveats apply.
 
>the error rate can be as high as 82% with an average of over 40% (mostly
>false positives).
 
Criticizing the reliability of current testing is unproductive without
having a better, alternative test available.  Anyone can try to discredit a
test by describing the maximum error rate ever found, but the *average*
error rate is more important in terms of public health.  As for specific
types of errors, a high rate of false positives is not necessarily bad for
the purposes of testing.  Yes, this means that some ferrets will be wrongly
identified as having rabies, but NO test, not IF or any other is 100%
perfect.  That's reality.  The HIV test has lots of false positives...the
first test is highly sensitive but results in quite a few false positives.
The test is repeated using the same assay, and if still positive, a second
type of assay is used that has very few false positives.  The important
aspects of a test for guarding public health are having a low *false
negative* rate and a high positive predictive value, all of which I can
explain in detail to anyone who wants to email me.  The savage reality of
rabies is that the virus usually must be found in nerve tissue, and that
usually means the death of the animal.  IF just isn't going to replace
microscopic examination of brain tissue right now.  I don't approve, I only
predict how the public health community will react.
 
>[The rabies shedding studies in ferrets] already [comprise] more data on
>more strains than were tested to establish a quarantine for dogs.  How much
>is enough??
 
Unfortunately, a few more ferrets will probably pay with their lives in
additional shedding studies if *all* public health officials are to be
convinced.  The alternative is that even more ferrets will die following
bite incidents.  As for dogs--dogs have been *the* major source for rabies
transmission to humans for *millennia* and using quarantines for dogs was
well established by the time anyone got around to studying it
scientifically.  Although we know better, public health directors are
generally not aware that ferrets have been domesticated for more than 1,000
years (probably longer) and kept as pets for centuries.  Even though no
cases of ferret-to-human rabies transmission have been documented, the
stigma remains that ferrets are "exotic" and "wild." I can't change that
perception alone.  Every ferret owner must be an ambassador to represent
them in the proper light.
 
>>Rabies is one of the few viral illnesses that is 100% fatal in humans once
>>symptoms develop.
>Let's look calmly at the *facts*.  <SNIP> Rabies is not adapted to a human
>host.  Even if you are bitten by an obviously rabid, foaming at the mouth
>animal, your chances of contracting rabies from a single exposure are, at
>best, 15-20%.  Rabies can be effectively treated in humans with near 100%
>results up to the time clinical signs begin <SNIP>. If caught immediately
>rabies can still be treated with a 1-3 chance upon onset of symptoms.
 
All true, but it doesn't change the irrational attitude toward certain
infections by the public or by public health officials who are supposed to
know better.  When Laurie Garrett, author of "The Coming Plague," returned
from Surat, India, after investigating the outbreak of pneumonic plague, she
was greeted at the airport by a infectious disease team that forced her to
sterilize all of her possessions and shower with disinfectant, even though
plague is easily treated with the simplest of drugs and its mode of
transmission is well known.  BUT, after returning from Kikwit, Zaire, where
Ebola had reemerged, she breezed through customs and no one stopped her,
even though Ebola is fatal in 85% infected persons, it is not easily treated
at *all* and, at the time, its mode of transmission wasn't fully known (it
CAN spread by air).
 
How can public health officials be "truthful and realistic about the risk"
of rabies when so many of them don't know jack about the risks of MANY
infectious diseases or are unwilling to stand up to a hysterical parent of a
bitten child and refuse to destroy an animal that has almost zero risk of
carrying rabies.  There is no shortage of stupidity on the part of many
people when it comes to protecting their backside, avoiding a scandal or
making/saving money.  Tell me why Britain will slaughter 11 million
otherwise healthy cattle to assuage the fears over BSE?
 
I can't take credit for the stupidity or intransigence of others even when
they're colleagues.  I *can* help by telling folks on the FML how many
public health officials will react to changes in rabies testing and allow
FML members to prepare appropriately.  Arguing the unfairness of current
health policies will upset many people here but won't matter a whit to the
officials who decide which animals live or die.  I anguish over the fact
that ferrets will die in rabies shedding studies, but to convince all public
health officials that ferrets pose a near-zero risk of transmitting rabies,
those studies are the shortest way to that end.  Certainly, some people
*can* be convinced based on existing data--but not all.  Here in North
Carolina our state vet doesn't like ferrets and feels they shouldn't be
pets.  He campaigned against their legalization.  And some health officials
are more hostile and resistant to change and less willing to learn than he
is.  With shedding studies complete for all forms of rabies, ferret owners
in North America could take the data to state or provincial legislatures and
ask for legislation to override such health officials.  Without complete
data, it's more likely we'd get shot down and probably make entrenched
enemies of ferrets among some health officials.
 
--Jeff Johnston ([log in to unmask])
[Posted in FML issue 1554]