'Love at first sight'
Holland's Dr. Wil Landman and Herman Peek talk about their interest in Eimeria, concerns about resistance and next steps for improving control.
 Peek and Landman: 'We inspire each other'
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Editor's note: Much has been written and presented in recent months about live coccidiosis
vaccines and their ability to restore the sensitivity of Eimeria organisms "the
ones that cause coccidiosis in poultry "to ionophore antibiotics, chemicals and other
in-feed anticoccidials that have lost some effectiveness from overuse in the field.
The last issue of CocciForum (No. 10), for example, carried a report about a study conducted
in the Netherlands by Dr. Wil J.M. Landman and Herman W. Peek of the Animal
Health Service, Ltd. in the Netherlands describing an association between the use of
Paracox-5 and higher sensitivity toward anticoccidial drugs of Eimeria spp. field isolates.
Shortly afterward, Landman and Peek authored an article on the same topic for
World Poultry (No. 7, Vol. 21) and presented their research at the IX International
Coccidiosis Conference in Brazil.
The managing editor of CocciForum recently visited Landman and Peek at their lab in
Deventer to learn more about their focus on coccidiosis and the challenges facing the
industry.
CF: THESE DAYS IT'S HARD TO TALK
ABOUT EIMERIA RESISTANCE TO
IONOPHORES AND CHEMICALS
WITHOUT YOUR NAMES COMING UP
IN CONVERSATION. WITH ALL THE
POULTRY HEALTH PROBLEMS YOU
COULD STUDY, WHY THE FOCUS ON
COCCIDIOSIS? WAS THERE SOMETHING
IN PARTICULAR THAT FASCINATED
YOU ABOUT THE DISEASE?
PEEK: For me it started in 1984. At
first I worked at the University of
Utrecht with toxoplasmosis, and the
diagnostic techniques used for that
disease are almost the same for coccidiosis.
Later on I also worked with
Dr. Matty Vertommen (now with
Schering-Plough Animal Health in
Benelux) "a great inspiration. So
together we built up a lot of personal
interest in coccidiosis. We knew it was
a costly disease for the poultry industry
and, as scientists, we like to solve
problems. That's what got me started.
LANDMAN: I guess I got the calling
when I was a little younger. I was 8
years old when I knew I wanted to be
a vet. And I loved birds. So it got to
be a combination between something
with feathers and animal disease. I
ended up in a poultry house. And
within the poultry industry, I've
touched a number of disease areas.
At the Animal Health Service, we don't
have the opportunity to devote our
entire lives to working with one disease
in one species. But in our case,
since we are close to the field, we
need to cover a large part of poultry
healthy and give priority to what the
field demands "and one of those
areas is coccidiosis. I've been working
with coccidiosis with Hermann for the
past 3 years.
CF: OVER THE LAST COUPLE OF
YEARS, WHAT SORT OF TRENDS
DO YOU SEE DEVELOPING IN THE
INDUSTRY WITH RESPECT TO
EIMERIA STRAINS AND MANAGING
COCCIDIOSIS?
LANDMAN: My concern is that producers
are getting used to the problem.
They don't see coccidiosis for what it really is "a costly disease
that can have a big impact on their
operation, often without them knowing
it. In every flock there is coccidiosis.
How much it affects an operation
depends on whether the farmer recognizes
that it's a problem and how he
goes about managing it.
PEEK: Unfortunately, many producers
don't recognize Eimeria resistance
when they see it. They think they're
controlling it with a drug or chemical,
and they probably are to some extent.
But they don't know how well that
drug is actually working. Often they
are losing performance and they're
not aware of it. They're getting used
to the disease being in their flocks.
They're not aware that there are ways
to make the drugs work better. They
don't know there's resistance building,
but they're seeing losses in performance.
CF: SO HOW DO YOU, AS SCIENTISTS
IN A LABORATORY, GET INVOLVED
WITH CHANGING THEIR PERSPECTIVE
ON COCCIDIOSIS CONTROL?
WHAT I'M HEARING IS THAT PRODUCERS
AREN'T EVEN AWARE THAT
THEY HAVE A COCCIDIOSIS PROBLEM,
AND IT'S VERY RARE YOU SEE
AN ACUTE OUTBREAK OF IT.
LANDMAN: That's true to some
extent. Overall, our impression is that
problems in the field do not correlate
directly with the degree of resistance
that we find in the lab, so that tells us
we still have a lot to learn about this
organism. We think it might be related
to the fact that sometimes there is still
some residual effect of anticoccidial
drugs, even though they will show
resistance in the lab. That residual
effect might slow the infection a little
bit and perhaps induce a natural
response against the parasite. That
might be one of the reasons why
people in the field are not seeing the
major outbreaks, but still the drugs are
underperforming.
PEEK: We saw the difference in coccidiosis
control when diclazuril
(Clinacox) was introduced in Europe
several years ago. Producers experienced
better performance because it
was a new anticoccidial. They had
become used to having a high incidence
of subclinical coccidiosis in
their flocks, but they didn't realize it
until they got such a tremendous
boost in performance from the new
chemical. Unfortunately, diclazuril was
overused by some operations and
Eimeria eventually built resistance to
that product, too.
LANDMAN: Over the last few years,
we have seen a steady increase of
cases involving Eimeria resistance -
and the incidence is quite high.
CF: SO WHAT KIND OF REACTION DO
YOU GET FROM VETERINARIANS
AND PRODUCERS IN THE FIELD
WHEN YOU COME BACK
AND SAY EIMERIA
SPECIES ARE DEVELOPING
RESISTANCE TO THE
DRUGS THEY'RE USING?
LANDMAN: It's difficult
because, as we said earlier,
they're not even aware
that have a problem.
They're not seeing the
performance losses, even
though we know they are
there. Some of the anticoccidial
drugs have a
growth promotion effect,
but the drugs are not
intended for that purpose.
If you look at the drugs
strictly for what they're meant
to be "anticoccidials -then
you could say they're not performing
as they should.
CF: NOW THAT ANTIBIOTIC GROWTH
PROMOTERS ARE BANNED IN
EUROPE, DO YOU THINK THERE WILL
BE MORE OF A TENDENCY TO USE
IN-FEED ANTICOCCIDIALS TO GET
SOME OF THAT GROWTH PROMOTION
EFFECT?
PEEK: They might, but the ionophores
and chemicals are supposed
to be used for coccidiosis control
only. They're not approved as growth
promoters and shouldn't be used for
that purpose.
LANDMAN: And if they do use them
for growth promotion, that certainly
won't help to improve the growing
resistance problem with Eimeria, that's
for sure.
CF: IN YOUR RESEARCH, WHERE YOU
STUDIED THE SENSITIVITY TO
DICLAZURIL AND MONENSIN OF
EUROPEAN EIMERIA SPECIES FIELD
ISOLATES AND FOUND AN ASSOCIATION
BETWEEN HIGHER SENSITIVITY
TO THOSE ANTICOCCIDIALS WHEN
ISOLATES ORIGINATED FROM FARMS
FOLLOWING A VACCINATION POLICY,
WERE YOU SURPRISED BY THE
RESULTS?
PEEK: Not really. It was a very interesting
and nice finding. Although
direct proof of restoration was not
obtained in this study (for that matter
another design is required), it strongly
suggested it. Restoration has been
shown by others previously "Dr.
[S.J.] Ball in the 1960s being the first
"then others have shown this using
virulent coccidial vaccines. But I
believe our work is the first suggesting
this response after using an attenuated
vaccine. So in that sense, it was
a bit unexpected, but not if you look
at the whole context of restoration of
sensitivity.
CF: WHY WOULD THAT BE UNEXPECTED
WITH AN ATTENUATED
VACCINE?
PEEK: Possibly because non-attenuated
vaccines will replicate sensitive
oocysts more aggressively, but our
work suggests that it may also occur
with an attenuated vaccine. Not in all
cases, but in half of the cases. In the
other half there was always a non-significant
trend toward more sensitivity.
CF: SO HOW FAR CAN YOU TAKE THIS
WORK? YOU'VE MADE GREAT
STRIDES IN DOCUMENTING RESISTANCE
AND YOU'VE SHOWN HOW
SENSITIVITY CAN SHIFT AS PEOPLE CHANGE THEIR PROGRAMS, BUT
WHAT'S THE NEXT STEP IN YOUR
RESEARCH WITH COCCIDIOSIS?
LANDMAN: We have more plans, but
we lack funding.
CF: WHAT WOULD YOU LIKE TO DO?
WHAT WOULD THE NEXT STEP BE?
PEEK: One of the things we'd like to
do is to show the mechanism behind
the restoration of resistance. Some say,
well, it's just displacement of the
resistant strain, which I personally
don't believe because our sensitivity
tests show that, when you find an
increase in sensitivity, it's not a blackwhite
thing.
Is it a full replacement of the resistant
strain? What is the sensitivity of the
vaccine strain? We have found intermediate
patterns of sensitivity.
Some scientists ask if there is some
genetic interbreeding between a resistant
and a sensitive Eimeria strain -
and that seems a more logical thing to
happen. Then you could also have
combinations of both strains, and
that's probably the case. It would be
nice for someone to dig into it and
find out.
CF: YOU BOTH WENT TO BRAZIL
LAST SEPTEMBER FOR THE IX
INTERNATIONAL COCCIDIOSIS
CONFERENCE, WHERE YOU MET
WITH ALL THE TOP COCCIDIOSIS
EXPERTS IN THE WORLD. YOU PRESENTED
YOUR SENSITIVITY
RESEARCH TO A VERY WELL-EDUCATED,
ANALYTICAL AUDIENCE.
WHAT WAS THE TOUGHEST QUESTION
THAT YOU RECEIVED?
LANDMAN: We didn't get one. I think
the audience understood our story
very well. The main question is, what
is the mechanism behind restoration
of sensitivity? That's the thing that
people are trying to understand and
document. Because that might teach
us more about coccidiosis and how to
prevent it.
CF: IS THERE SOMEBODY IN THE
FIELD OF COCCIDIOSIS RESEARCH
THAT THE TWO OF YOU REALLY LOOK
UP TO?
PEEK: I like Dr. Ray Williams in the
UK. Because when I read his articles,
I feel like I'm talking to him. He's having
the same thoughts about it.
LANDMAN: Yes, I think I'm along the
same line, but there are other very
inspiring names also.
CF: JUST BECAUSE OF THE WAY HE
WRITES?
PEEK: And the way he does his
research, of course. And the solutions
he proposes. The way he's thinking
about the problems that he sees. I like
his approach.
CF: HAVE YOU SEEN ANY PARALLELS
BETWEEN THE WORK YOU HAVE
DONE WITH COCCIDIOSIS AND ANY
OTHER POULTRY DISEASES? OR DO
YOU THINK THAT YOUR RESEARCH
MIGHT IMPACT ANY OTHER AREAS
OF POULTRY DISEASE MANAGEMENT?
LANDMAN: That's an excellent question.
Yes, there are parallels but I
don't think scientists are that original,
let me say that first. We tend to copy
and learn from each other. A finding
in a given species/circumstance by an
author may prompt another to see if
that same discovery applies to another
species/circumstance. We are playing
variations on a similar theme. The creativity
lies in composing slightly different
melodies that will help us understand
what lies beneath using each
other's information.
PEEK: Well, I like to say that we
inspire each other. And generally, we
learn from each other, and we learn
also from other animal species or
other work that has been done. It
goes back and forth. From the resistance
work, yes, I think it's similar for
other diseases. In bacteriology, for
instance, when you have resistance
problems you try to find another
antibiotic or another program. If you
don't have antibiotics or if residues
are a problem, you might try a vaccine.
That's the trend in poultry for
coccidiosis.
CF: WE'VE TALKED ABOUT GOING TO
INDUSTRY CONFERENCES WHERE
PEOPLE ALREADY KNOW YOU, BUT
WHAT HAPPENS WHEN YOU'RE AT A
COCKTAIL PARTY AND SOMEONE
COMES UP AND SAYS, "WHAT DO
YOU DO?" HOW DO YOU ANSWER
THAT QUESTION?
LANDMAN: I always say that I'm a
chicken doctor. And they respond,
"You're a what?" Sometimes people
don't even know there are billions of
chickens in the world. They don't
think about where their food comes
from. That's one of the problems of
our time, I think. Due to all the luxuries
that we have, we have become so
distant from nature that we think that
meat and eggs come from a little hole
in the wall. Like you can just open a
drawer and there you have an egg.
And people don't realize that for producing
eggs and meat, affordable buys
for such a large human population,
you need to build large-scale operations.
But when you start explaining
about it and they understand what the
impact is, and the importance of having good health care for the poultry
industry, it makes sense to them.
CF: WHAT'S YOUR TYPICAL DAY LIKE
HERE AT THE LABORATORY, IF THERE
IS SUCH A THING?
PEEK: Every day is different. One day
you may have animal experiments to
do, another laboratory testing, then
statistical analyses, etc.
CF: DOES IT EVER GET MONOTONOUS?
DO YOU EVER COME TO
WORK SOME DAY AND SAY, "I'M
GETTING TIRED OF COCCIDIOSIS. I
WANT TO WORK WITH NECROTIC
ENTERITIS OR MYCOPLASMA" ?
PEEK: I guess I'm just frightened,
because I don't have those thoughts.
CF: BECAUSE YOU'RE ENJOYING
WHAT YOU DO.
PEEK: Yes, I think so. I'm never bored
here.
LANDMAN: When you explain to people
that you do research, they tend to
think it's boring with all this data, all
this attention to detail. But it's not boring
at all, because it's all different. We
always have different projects, different
questions to be answered. It's a
whole project "from animal experiments,
to writing papers, to visiting
congresses, to visiting farms. There's
quite a lot of travel involved. It's really
varied, so I would say it's a great job.
I get to see the world because of
chickens.
PEEK: For me the whole chicken
pathology was love at first sight. And I
will enjoy it every time I see pathology
happening. It's fascinating. I can
just gaze at these lesions and marvel at
how it all happens. So it never gets
boring. I think this work comes from
the heart. It's the only way to keep
on.
CF: SOMETIMES WHEN PEOPLE
CAN'T SLEEP, THEY COUNT SHEEP. DO
YOU COUNT OOCYSTS?
[laughter]
PEEK: No, because I don't think they
would put me to sleep. I have an
emotional connection with coccidiosis,
but it does not prevent me from
sleeping.
LANDMAN: I can sit for hours at a
microscope and look at nothing but
Eimeria oocysts. The sporulation
process, for instance, is absolutely fascinating,
especially with Eimeria
maxima because the oocysts are big.
CF: IT SOUNDS LIKE YOU REALLY
LOVE YOUR JOB.
LANDMAN: Yes, very much. It's
extremely rewarding.
PEEK: And there's still so much we
don't know about coccidiosis. We have
a lot to keep us busy.
Source: CocciForum Issue No.11, Schering-Plough Animal Health.
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