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Top Dog - Dr Rae Fischer well ahead of the pack Shedding Light on Spray Cabinet Vaccination Veterinarians present a visual guide to managing coccidiosis. COCCI FAQs Raising broilers without growth promoters and anticoccidials Dr. Wil Landman and Herman Peek talk Eimeria COCCI News News From Schering-Plough

'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’

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.