The Eimeria biological cycle is a very complex one and is comprised of intracellular, extracellular, asexual and sexual stages. It is of paramount importance its understanding as its comprehension helps to understand the parasite epidemiology in the field, its pathogenicity and immunobiology.
Seven species of Eimeria (E. acervulina, E. brunetti, E. maxima, E. mitis, E. necatrix, E. praecox and E. tenella) are recognized to be causative agents of coccidiosis in chickens of the genus Gallus gallus.
Continue reading Eimeria biological cycle: an example of perfect complexity in biology
Coccidiosis in poultry is one of the diseases that probably cause most damage in the broiler rearing industry. It is not a case of producing high mortality within flocks but a subclinical process affecting economic performance, greater use of antibiotics and a loss of environmental farm conditions that will probably affect animal welfare.
E. praecox in the duodenum: A type of coccidiosis that is not clinical but causes a decrease in growth and feed conversion.
Coccidiosis in poultry has become a truly complex disease that is not only an intestinal disease but also involves other issues that affect global production. In the past, coccidiosis was diagnosed as a clinical disease –even by the farmers- with coccidiosis caused by Eimeria tenella being the most simple example of this disease.
Continue reading Coccidiosis in poultry: challenges for the industry
Prevention of coccidiosis in poultry relies on live vaccines. Ionophores act as coccidiostasts by maintaining a certain level of contact with the oocyst parasite but vaccines are the only products that are able to generate a good level of specific immunity from the very beginning. Oocyst production in itself is a challenge for those companies producing vaccines
Vaccines have been considered as a method of control of coccidiosis since the early 1950s when the first products appeared. In view of the complexity of the immunity established to fight against the disease, it is necessary to work with the infective part of the parasite, i.e. the sporulated oocyst. This has been the mode of action of coccidiosis vaccines. The first vaccines were produced from pathogenic oocysts gathered in the field.
Microscopic picture (x400) of the oocysts of 5 species included in HIPRACOX® vaccine.
The oocysts were roughly processed to obtain a suspension containing a minimum quantity of sporulated oocysts. Obviously, at this time it was quite difficult to obtain a uniform number of these oocysts and the process of sporulation could not guarantee the number needed for complete immunization.
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Coccidiosis in chickens is one of the more common and widespread diseases. Since the beginning of the industrial production of broilers, veterinarians and farmers have been trying to control this costly parasite.
The annual cost is believed to be around $1.5 billion/year. The cost of coccidiosis in chickens is based on direct production losses and indirect costs through the application of control measures.
In the past, the fight against the different Eimeria species was through the use of several molecules in the food. The first chemicals used against coccidiosis in chickens were introduced in the 1950’s. It soon became clear that there were some efficacy problems with these molecules, in the sense that the Eimeria spp. present on the farms could develop resistance against them after they were used consecutively a couple of times on the same farm.
Continue reading Coccidiosis in chickens: It’s time for vaccination