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I found it scary/interesting so I figured I'd cross-post.

Canine Parvovirus Type 2c in the United States
Dr. Ben Hatler, NEOTECH, LLC

For many years vaccinated dogs have suffered and died from Canine
Parvovirus (CPV) infections. Since vaccination failed to protect these dogs, people
speculated that a new form of CPV was in our midst. Their speculation has
been substantiated by the recent press release from Oklahoma State University
which stated that a new form of CPV (CPV-2c) has been identified in dogs
across the United States by the Oklahoma Animal Disease Diagnostic laboratory 1.
The press release stated that the 2c strain affects puppies and adults, can
attack the heart and intestines, and that the mortality can be quite high.
The most alarming aspect of the press release is its implication that
currently available vaccines are not protective against this lethal CPV-2c strain.
This is obviously troubling news fore all dog owners. So we must ask, is
the press release completely true, or does it contain exaggerations intended
to whip up unnecessary hysteria?

The press release is based on the results of a study published by Dr. Kapil
and his colleagues in the Journal of Clinical Microbiolgy2. In this study,
tissue and fecal samples were collected between February 2006 and August
2007 from 54 dogs with confirmed CPV infections. Canine parvovirus type 2c was
identified in 48% of the dogs while CPV-2b was identified in 46% of the
dogs. The researchers also that 66% of the dogs infected with various strains of
CPV had previously received a vaccination.

Since implications of the press release are so frightening, we must dig
deeper into the CPV-2c story to fully understand what it means for dog owners
and breeders. The emergence of this new strain of CPV is not surprising
considering the history of CPV and the high rate of viral evolution associated
with its initial emergence in the 1970s. Since the emergence of CPV type 2
(CPV-2) in the 1970s the virus has mutated. The v irus mutated into 2 strains
known as CPV-2a and CPV-2b. In 2000 scientists in Italy were the first to
report the emergence of CPV-2c in dogs. Since that report, CPV-2c has been
reported in Western Europe, Asia, and South America.

Now that a new strain of CPV is present throughout the world, the question
arises: What is meant by the term new strain? We need to realize that the
term new strain actually means genetic variant. In order for a strain of
parvovirus to be labeled a new strain, at least 1 of its approximately 5000
nucleotides must be different from a previously identified strain. This is the
case of the CPV-2c identified in the United States. Genetically speaking,
CPV-2c differs from CPV-2b by only a few nucleotides. In other words, from a
genetic standpoint, the new strain(CPV_2c) is over 99% identical to the old
strain (CPV-2b).

So there is very little genetic difference between CPV-2a, CPV-2b, and
CPV-2c. Does this sligh t genetic variation make CPV-2c biologically different
from CPV-2a or CPV-2b? The most prolific researcher of CPV-2c in Italy
concluded in a research report that CPV variants (2a, 2b, and 2c) have similar
biological behaviors3. In that research report, tissue distribution of CPV was
similar across all 3 genetic variants of CPV. Canine parvovirus type 2a,
2b, and 2c were all found in the intestines and in the heart. So the fact that
CPV infects the heart and the intestines is not new information and is not
specific to only CPV-2c. In another paper that investigated the occurrence
of CPV-2c in the United States, researchers stated that dogs infected with
CPV-2c exhibited clinical signs and outcomes that were similar to dogs infected
with CPV-2a and CPV-2b4. So death of dogs due to CPV infection (be it 2-a,
2-b, or 2-c) is not new information and it is erroneous to suggest that
CPV-2c is more lethal then older CPV strains.

Since CPV-2c has been discovered in the United Stat es, what are dog owners
and breeders to do? According to the press release, new vaccines should be
formulated since previously vaccinated dogs have contracted CPV-2c. Should
you switch vaccines? Should you demand vaccine manufacturers make a new
vaccine that protects against CPV-2c? The answer to the 2 previous questions
would be yes if we did not have some suitable vaccines currently available for
use. With the information now available in the scientific literature, I
believe that there is no reason to suggest that the currently available effective
vaccines will not protect against CPV-2c. Let me explain why I believe this
to be true.

First, a recent research report indicated that one of the original modified
live CPV vaccines (based on an old strain of CPV) was protective against
CPV-2c. This study reported that after CPV-2c challenge, vaccinated pups did not
become ill while unvaccinated pups showed clinical signs of canine
parvovirus5. In other words, on of the fir st vaccines, which was formulated years
before CPV-2c was identified, was able to induce protection against this new
genetic variant known as CPV-2c.

Second, certain effective CPV vaccines protect puppies against both CPV-2a
and CPV-2b. Since there is very little genetic variant and no known
biological differences between CPV-2a, CPV-2b, and CPV-2c, why wouldn't these
effective CPV vaccines protect against CPV-2c? To my Knowledge, no one has data to
definitively answer the question posed above.

Third, NEOPAR© has been tested in a kennel in Oklahoma where this new
genetic variant was diagnosed by the Oklahoma Animal Disease Diagnostic
Laboratory. NEOPAR©, when used properly, stopped the CPV-2c in its tracks just like
it stops a CPV-2a and CPV-2b outbreak.

One disturbing aspect of the press release and Dr. Kapil's paper was that
vaccines do not protect against CPV-2c. In Dr. Kapil's study, 66% of the dogs
were previously vaccinated. It is important to rea lize that not all
vaccines stimulate protection after just one, or multiple, doses. Immunity is often
not stimulated by vaccination if the animal is stressed, has a suppressed
immune system, or if the vaccine used is sub-potent (few vaccine particles
per dose). Unfortunately, the complete vaccination history for each dog in Dr
Kapil's study was not provided. So, it is possible these dogs could have
been vaccinated after they were exposed to CPV or they may have been vaccinated
with a sub-potent vaccine prior to CPV exposure. Many sub-potent vaccines
are on the market today and were not formulated to work in the face of the
high level of maternal antibody when pups are first vaccinated at 5 to 7 weeks
of age. This high level of maternal antibody can render a sub-potent
vaccine ineffective. Another important point of Dr. Kapil's study to consider is
that vaccinated dogs were infected with CPV-2b and CPV-2c. Of the 36
vaccinated dogs in which CPV was identified, type 2b was presen t in 15 dogs and type
2c was present in 19 dogs. So, not only did vaccination fail to protect
these dogs against CPV-2c, vaccination also failed to protect them against the
older genetic variations of CPV. Clearly, vaccines do not immunize 100% of
vaccinated dogs and this is also not new information.

At the present time, we know very little about CPV-2c. However, information
present in the scientific literature suggests that CPV-2c is very similar
to CPV-2a and CPV-2b; and, that vaccines developed prior to the discovery of
CPV-2c protect dogs from CPV-2c challenge. Even though the full CPV-2c story
has not yet been established, this has not stopped people from making
predictions of doom and gloom. Lets not get bogged down by the press release
intended to whip up hysteria in hopes of creating an economic opportunity for a
research institution. Let's wait until we have more relevant facts about
this genetic variant before we recommend changing the existing vaccination
protoc ols that have been so successful for so many years. In essence, all that
Dr. Kapil's report stated is that CPV-2c (along with other old genetic
variants of CPV) has been identified in previously vaccinated dogs in the United
States. So the implications of the press release of widespread death due to
an extremely pathogenic new strain of CPV are a bit far reaching. Let me be
clear. Dr. Kapil's study is scientifically sound and the results are clear
and straightforward, but the press release is an exaggeration of what is
known and speculates on what we do not know.


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21,195 Posts
there have been a couple of outbreaks following dog shows in MI (UKC shows) but it was unclear as to the actual vaccination status of the dogs. Three young labs died, but they were breeder vaccinated and therefore the proper handling of the vaccine was in some question. In the other outbreak the dogs were titred, not vaccinated.
I had asked my vet about this over a year ago when it cropped up, and he said that most of the current parvo vaccines from the big manufacturers do seem to protect against 2c.
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