Re: [Alpacasite] Re: Anyone giving BVD vaccine?

A couple of points:
1. a PI cria can also show antibodies in a serum neutralization test. We
had one that did on its first SN test (very low levels) and the assumption is
it got those antibodies thru the dam's milk. On that cria's second SN test,
no antibodies were found. Very confusing to simple minds like mine.

2. This one I do not fully understand but this is what I have been told: A
female with antibodies can in fact have a PI cria. Even though she has
antibodies, I have been told that the new exposure MAY be able to pass thru the
placenta and affect the cria. This is especially true of a dam who gave birth
to a PI cria and is pregnant again. To me this implies a vaccine would not
be effective because I would think a vaccine would work the same as an
exposure - both build antibodies.

3. I agree with Sue about the PCR test is only effective for that day.
However the reason why I think it is a good idea for shows, auctions and
breeding farms to implement a "PCR negative" test requirement is because it would
identify PI crias. You will never be able to eliminate all risks, but with a
PCR negative requirement, you significantly reduce the risk at a show or
auction. PI animals are much more contagious (sheds more of the virus) than a
non-PI animal who gets the disease.


Steve McCarthy
Spruce Ridge Farm
Old Chatham, NY
www.spruceridgefarm.com

In a message dated 12/11/2005 3:07:36 P.M. Eastern Standard Time,
sue@andesdandies.com writes:

I'm echoing Neil on this one with a little follow up. A vaccinated
animal will show positive for antibodies, not the disease itself.
Being positive for antibodies is a GOOD thing when animals are
exposed to groups of other animals...

The PCR test will show if the animal has active current infection of
the virus. A positive PCR on a newborn cria means it's a most likely
a PI. To know for sure, do a follow up PCR in a few weeks to see if
it's still positive, followed by a SN (below) to see if antibodies
are present. Animals who are not currently infected either because
they never have been exposed or they had it once and recovered and
now have antibodies, will test negative to the PCR test. One big
problem is that, just like with an AIDS test in humans, a negative
result is only good FOR THAT DAY - if any change happens after that
test, such as a new cria is born on the farm, an animal goes off the
farm & returns, a new animal comes to the farm, the tested animal
goes to a show or to a breeding farm on a transport trailer with
other animals from other places who were not tested - there may have
been exposure, and a new test might be different.

A Serum Neurtralizing test (SN) screens for presence of antibodies -
meaning the animal was exposed/infected in the PAST and has developed
antibodies. The animal is NOT currently infected, not a risk of
exposure as it stands. PI crias will never test positive on a SN as
they are persistently INFECTED and don't, by definition, develop
antibodies, hense the problem. The ideal would be to have females who
ARE positive for the antibodies, but that they were not exposed
during the risky time of their pregnancy. Was the exposure 2 years
ago, last month, or when? Most critically, was it when she was in
early pregnancy, thereby risking producing a PI cria.

So, SN positive pregnant females should be isolated before delivery
to test their newborn cria to see if it is PI. It may not be. Even if
she was infected during the opportune window, which in cows is 40-120
days (about), don't know about alpacas, she may not have a PI cria.

Negative PCR tests prior to shows are not foolproof, and there is a
misunderstanding that the test only needs to be done once for reasons
stated above.

There will be a lot of fear and misinformation and misunderstanding
as this is all sorted out, and the recommendations may very well
change as research is done on alpacas to determine how the virus
actually behaves in these animals. It is not a new disease, it is
just new to us since we just started to look for it. Obviously, since
it's been around all these years, we just didn't know it, it has not
been terribly insidious - we have not heard of entire breeding herds
being wiped out mysteriously, etc. As with other viruses, not every
animal exposed will contract the disease. Healthy animals in low
stress environments will very likely be able to fend it off like they
do other viruses such as WNV, but some will not.

Sorry, what started out as being a quick added point got a little
more involved, but I think it's info we all need to be familiar and
comfortable with.

best regards,

Sue Zelazny
Andes Dandies, LLC
http://www.andesdandies.com
Middleport, NY

--- In Alpacasite@yahoogroups.com, "mpcpneilp" <mpcpneilp@a...> wrote:
>
> Laurel,
>
> I have heard this arguement against giving vaccinations, and I
simply
> don't understand it.
>
> If an alpaca tests positive for BVD antibodies IT IS IMMUNE TO BVD!
> An immune alpaca is not a carrier and poses now risk to it's
> penmates. Further, a PI would by definition not be positive for
> antibodies. Given the choice, would you want an alpaca that is
still
> vulnerable, or an alpaca that was immune?
>
> Am I missing something here?
>
> BTW, this is not to suggest that I am in favor of broadly using
> vaccine for BVD at this time. I'm not.
>
> Neil
> A Paca Fun Farm
> Mt. Airy, Maryland
> Sugarloaf Mountain, Maryland
> www.apacafunfarm.com
>
> --- In Alpacasite@yahoogroups.com, "Shouvlins" <bluebirdhills@v...>
> wrote:
> >
> > Time is short here, so I have been whisking through posts and
this
> may have already been posted...so I apologize if I am repeating
> something already said...
> >
> > One caution about using vaccine is that after using the vaccine,
> your animals will probably test positive for BVD. The reason is
that
> the vaccine stimulates your alpaca to produce antibody to the the
BVD
> virus. Tests for BVD check for the presence of the antibody to
that
> virus, and the antibody's existence in your alpaca implies that it
> has mounted an immune response to the virus and it is concluded
that
> it has "had" the disease. Most of us have had tetanus
immunizations
> and would probably all test positive for the presence of tetanus
> antibodies.
> >
> > So before you go and immunize your herd, you might want to ponder
> the consequences of your herd testing positive for BVD when it may
> never have been exposed in the first place. If BVD tests become
> standard for sales, moving across state lines, or stud contracts, a
> positive test might interfere with all of that. The closer the
test
> is run to the time of immunization, the more positive the test will
> probably be.
> >
> > If I immunized an 2 years ago and the antibody level is low, but
> present nonetheless, how will that be interpreted by the individual
> considering purchase of that alpaca? I guess if it were I, I would
> mve on to another animal that was definitely negative.
> >
> > Perhaps it would make sense to test your alpacas first, and upon
> receiving negative results for BVD, then immunize against it, and
> document, document, document?
> >
> > Laurel
> >
> > Tim & Laurel Shouvlin
> > Bluebird Hills Farm CSA & Alpacas
> > 3617 Derr Rd. Springfield, Ohio 45503
> > www.bluebirdhills.com
> > bluebirdhills@v...
> > 937-390-6127 or 937-206-3936 (cell)
> > ----- Original Message -----

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