Eimeria parasite threatens every broiler flock
Parasites of the Eimeria type can cause coccidi- osis. This parasite is universally present and sur- vives in a form (a so-called oocyst) that is very resistant to environmental factors. Oocysts de- velop further outside the broiler into infectious stages that can survive in manure for weeks and in soil for months. Coccidiosis is a collective name for several gut infections in poultry that are each caused by a different type of Eimeria (Eimeria acervulina, E. brunetti, E. maxima, E. necatrix and E. tenella). In addition to that, there are two more Eimeria- types (E. mitis and E. praecox) that are often
not recognised as a disease, but do cause dam- age in poultry. Almost all flocks suffer from a form of coccidio- sis. Most birds come into contact with different coccidiosis types at a young age and are pro- tected from these types after several weeks, for the rest of their lives. In addition to financial damage as a result of diminished growth and feed conversion, coc- cidiosis (in combination with Clostridium Per- fringens) often causes wet manure and be- cause of that, sole lesions. Each broiler flock experiences coccidiosis, but it
does not always make them ill. Broiler farmers need to keep the pressure manageable. In ad- dition to good chick management (take for ex- ample feed quality, day-old chicks and climate) and thorough cleaning and disinfection of the poultry house after each round, this usually happens by adding coccidiostats to feed. Eimeria parasites can develop a reduced sensi- tivity to an anticoccidiosis agent. They can even quite simply develop a full resistance against synthetic coccidiostats. To prevent resistance problems, broiler farmers change agents now and then.
( oocyst) and is very resistant to environmental conditions. Fur- thermore, it occurs in all housing systems. A visit to the vet is not necessary to determine the parasite’s presence, which would also add unnecessary costs to the chain. Classification as an antibiotic also means meeting the strict production demands for antibiotics and again, more unnecessary costs. In addition to this, the use of coccidiostats as feed additives guarantees correct dosage, they can be evenly divided through the feed and this prevents over- or under dosage.
The Eimeria parasite can severely impact the broiler’s gut. 26
▶ POULTRY WORLD | No. 2, 2019
What about the development of resistance? So, what about the development of resistance – the parasite’s resistance against ionophore coccidiostats and resistance in humans? Research into the risks of the use of ionophore coc- cidiostats, conducted by the Norwegian Scientific Committee for Food Safety, indicates that using coccidiostats can lead to the development of resistance against the ionophore an- ti-coccidiosis agent and against the antibiotics bacitracine and vancomycine. These are used in human healthcare. The Norwegian researchers do note that their results are based on a limited amount of data and the Norwegian government does not limit their use. Ionophore coccidiostats have been used globally for years and up until this moment, a resistance by the parasite against the ionophore coccidiostats has not been discovered. The ionophores’ operating mechanism is unique in that pharmacologically, they completely differ from human and animal antibiotics or only human antibiotics. This means that they do not contribute to antibiotic resistance in humans. “The safety of ionophore anticoccidials is again emphasised by the fact that they are not on the World Health Organiza- tion’s list of medically critical antibiotics or the World Organi- zation for Animal Health’s list of antibiotics they monitor,” says Rolf Poelstra of Elanco Animal Health, one of the biggest pro- ducers of ionophore coccidiostats. Ionophore coccidiostats
PHOTO: FABIAN BROCKÖTTER
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