The poultry industry has devised many programs using drugs for the control of coccidiosis. Yet coccidosis organisms can quickly become resistant to drugs. Thus, in the spring and early summer “shuttle” programs are often employed in which a synthetic drug (so called “chemicals”) is incorporated in the starter feed and an ionophore in the grower. Rotation programs in which different drugs are used in successive flocks have also been widely adopted.
Vaccines An entirely different approach to the control of coccidiosis involves the use of vaccines. Vaccines in which birds are administered small numbers of sporulated oocysts have long been available in the USA. In the past vaccines have principally been employed during the rearing phase of egg-laying birds. The introduction of novel methods of administration (such as with a spray-cabinet in the hatchery) has made vaccination of broilers more feasible. Researchers are actively seeking better means to safely immunize birds against coccidiosis and although there are many technical hurdles to overcome, progress is being made and new vaccines seem likely in the future.
Problems As is often the case, success in controlling a disease is often accompanied by a downside. In the case of the coccidiosis parasite Eimeria has proved to be very adaptable, eventually acquiring resistance to the widely used drugs. It has therefore been necessary to constantly discover new compounds to replace those that are no longer effective. Unfortunately, this process is now vastly expensive and many companies have been discouraged from pursuing new drug discovery. Vaccines are seen as a likely alternative but, the decreased funding available for basic research into, for example, mechanisms of immunity may prevent progress in the future.
Management As long as chickens are raised on the ground and therefore in contact with their feces, then coccidiosis will remain a threat to the poultry industry. Good management however, plus the adoption of effective control programs, whether by chemotherapy or vaccination, can serve to reduce the risk. In 1991, following the first ever flock of broilers raised at the University of Arkansas Applied Broiler Research Farm at Savoy, we identified three species of Eimeria present in the litter. These species are still present today after many flocks have been successfully raised on the site. By a combination of good management and adoption of control programs recommended by the integrator, coccidiosis has not so far been a problem. It is hoped that this situation will continue in the future. //////////////////////////////////////////////////////////
In late 2005 Imugene and Abic Biological Laboratories Teva Ltd., began the development and evaluation for a new vaccine for the poultry coccidiosis prevention market.
Abic Biological Laboratories Teva Ltd is the animal health division of Israeli-based Teva Pharmaceutical Industries Ltd.
Coccidiosis is one of the most common and costly diseases in poultry and is prevalent worldwide. Apart from causing weight loss and poor feed conversion, the death rate in chicks and in adult birds can also be high.
Vaccine candidates are under preparation and construction by Imugene. These will then be trialled at the University of Technology Sydney. Abic Biological Laboratories Teva Ltd is funding the vaccine product development feasibility study which will combine Imugene’s patented Adenoviral Vector Delivery System with patented coccidia genes supplied and owned by Abic Biological Laboratories Teva Ltd.
A ‘non-vectored’ sub-unit coccidia vaccine is currently sold by Abic Biological Laboratories Teva Ltd for the poultry broiler breeder markets, for the maternal immunization of their offspring chicks in various countries. Imugene’s Vector Delivery System has the potential to allow a successful vaccine to be introduced to the much larger broiler markets by making the vaccine suitable and cost effective for administration on a large scale.
The new vaccine upon successful completion will enable the expansion of coccidiosis treatment from the small numbers of breeding and laying poultry to the massive broiler populations.
Upon successful completion of the trials and license negotiations and obtaining marketing authorisation Abic Biological Laboratories Teva Ltd will produce, sell and distribute the vectored coccidia vaccine with Imugene receiving royalty income. Abic is represented in the major poultry producing regions of the world.
About Coccidiosis Coccidia is the second biggest poultry treatment product category, second only to in-feed antibiotics.
The Imugene / Abic vaccine will be an overwhelming commercial proposition to poultry producers as its low cost of delivery to large poultry populations will position the vaccine to capture a major share of the market. As the vectored vaccine does not require injection, it is ideal for mass administration to many thousands of birds via their drinking water.
Current treatments for the disease in broilers is through the use of ‘coccidiostats’, a range of chemicals that control rather than completely prevent coccidiosis. Current coccidiostats are rapidly declining in efficacy due to developing resistance.
Use of coccidiostats is under increasing pressure from regulatory authorities and consumers. Chemical residues are of concern as is the constant emergence of resistant variants. However, since coccidiosis has such a dramatic impact on commercial poultry production it is unlikely that poultry industries will be forced to cease coccidiostat use unless there is a credible alternative like an effective and an economically viable vaccine.
Coccidiosis in chickens is caused by seven different species of coccidia (genus Eimeria), which are single celled parasites that live in the gut wall of their host. These coccidia are host specific: turkeys and other species are not infected by fowl coccidia and vice-versa. The different species of coccidia live in different parts of the gut and can be divided into those causing intestinal coccidiosis (the majority) or caecal coccidiosis (one species).
The magnitude of the impact of coccidiosis is such that disease control practices are essential. In 1997, sales of coccidiostats accounted for 3% of the US$17B world animal health and nutrition market (AH&N) and this has been predicted to rise to 3.5% (i.e. US$850 million) of the projected US$24.5B 2005 AH&N market.
About Abic Biological Laboratories Teva Ltd Abic is a quality producer of pharmaceuticals and veterinary products. Abic Biological Laboratories is wholly owned by Teva Pharmaceutical Industries Ltd. The veterinary division under the name of Abic has emerged as a major force in the Israeli veterinary market.
Teva Pharmaceutical Industries Ltd, headquartered in Israel, is among the top 20 pharmaceutical companies and among the largest generic pharmaceutical companies in the world. The Company develops, manufactures and markets generic and innovative human pharmaceuticals and active pharmaceutical ingredients. Close to 90% of Teva’s sales are in North America and Europe.
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