Volume 22 • Issue 05 • 2018
AvZ - 16 Sep 2013
I have seen a few confirmed cases of leucosis in
sheep, but none up to now in cattle. I will definitely
look a bit harder now. I think if we could get more
info from local Abattoirs it will help a lot. The
specific case you are referring to was actually an
incidental finding at an abattoir while we were
looking for something else. The communication
between veterinarians and abattoirs needs
urgent attention. Maybe somebody can comment
on this.
TC - 26 Sep 2013
One of the many frustrating things in our business
is that we are dealing with an inexact science! EBL
seems to be one of the most “inexact” and hence,
we gathered, our colleagues in the States threw
in the towel for a while, in trying to control let
alone eradicate the disease. There might be some
immune-suppressive gremlins at work, because
in herds with a high sero-prevalence there can
be minimal clinical cases for years, then all of a
sudden we begin picking up the mega-nodules
on rectal palpations and also autopsy cows that
have died. (That’s “vrot taal”, we don’t autopsy
cows that haven’t died.) Then again, those herds
go quiescent and other things like subclinical
hypocalcaemia and late embryonic deaths take
centre stage again.
We must admit, we haven’t done any large-scale
investigations of EBL levels for a long time;
probably because we really don’t know what the
heck to do if/when we find high sero-prevalence,
and secondly, as Rob pointed out, there are other
disease conditions that are equally, or more,
damaging to dairy economics, and that we CAN
do something about. This is an argument we use
when farmers have read about EBL in the lay
press and become excited. Perhaps, for a start as
with BVD we should encourage buyers, sellers
and agents to insist on only EBL sero-negative
animals exchanging hands. Having rectally
palpated nearly 2000 dairy cows last week (and
in herds that are certainly EBL positive) I shudder
to think of using a new glove for each one! When
the world/farm is Stomoxys free, then maybe we
can start talking …..?
TESTING, CERTIFICATION AND
EXPORT
LS - 23 Oct 2006
My opinion is, that the current certificate is
in general quite good and serves its general
purpose for breeding soundness of bulls for
self-use. However, when it comes to sale bulls
(option B), I feel a bit uncomfortable to say that
a bull is breeding sound without a negative
result for Bovine Leucosis, Brucellosis, BVD PI,
Trichomoniasis and Campylobacteriosis. These
tests should be compulsory and not optional.
AvZ - 15 Sep 2013
We had to test 250 heifers in Heidelberg, Southern
Cape, recently for export purposes. 20% of them
were sero-positive for EBL, yet I don’t see regular
symptoms or outbreaks of the disease. Maybe I
missed some of the cases, but we did not have
major outbreaks with lot of deaths.
PI - 16 Sep 2013
Albert. I wonder if any of these were false
positives ie. low specificity of the test. The reason
I suspect this is that as far as I know most animals
only seroconvert at 4 years of age when using the
AGID test. The ELISA, while it is more sensitive,
could possibly pick it up a bit earlier, it also takes
some considerable skill in interpretation. ... lab
personnel are like rugby refs; they can sometimes
be overzealous in their interpretation.
CN - 10 Nov 2014
I need some advice from the dairy vets. Have a
group of 36 pregnant heifers intended for export
to Zim. Tested BM, avian and bovine TB. Then
blood samples for EBL. Just received results from
the lab... 26 of the 36 tested positive for EBL.
There is no history of clinical EBL cases on this
farm and it's a group of heifers. Problem is that an
EBL-positive means NO export.
Advice required:
1. What now?
2. What information regarding EBL can anyone
share... the questions the owner will ask.
3. What is the implications regarding future of
these heifers?
I was only able to speak to the technician, there's
no vet available at lab to give advice.
JG - 10 Nov 2014
Which test was used for the EBL result? From
what I understand animals of any age can be
infected and the disease may be subclinical which
means that although the farmer may not have
noticed anything going on in his herd it’s possible
that it is there. Of course, re-testing may be worth
it but with such a high rate of positives from your
first sampling I think that false positive results
are highly unlikely, so farmer shouldn’t count on
this… Here is a good article on EBL
http://bit.ly/EBLarticle
Unfortunately, if EBL negative animals (on
serology) are the requirement for export to Zim
then your farmer should reconsider exports, but
if he/she is looking to maintain an export route
to that country then eradication would be the
21