Anticoccidial drugs and their effects upon the development of immunity toEimeriainfections in poultry

Abstract

The long-held view that anticoccidial drugs, to a greater or lesser extent, interfere with the development of immunity to Eimeria species may no longer be correct because few drugs, if any, are capable of preventing some degree of parasite multiplication. Acquisition of immunity is, therefore, a real possibility, providing suf® cient parasites are present in the environment. Immunity is an important consideration during the rearing of replacement layers, broiler breeders, turkeys, and gamebirds, but little research has been carried out on the effects of drugs on immunity development in these categories of stock. In recent years, there has been a change in the perception of the signi® cance of immunity in broilers, and some broiler producers have taken this into consideration when designing drug programs for use in the ® eld. Studies in¯oor pens and the ® eld indicate that broilers given various drug programs can develop immunity when exposed to natural infections but that this process takes time: solid immunity not developing until birds are 6 to 7 weeks of age. This suggests that drugs should not be withdrawn from the feed prematurely since birds may not have had time to develop adequate immunity.

Coccidiosis: recent advancements in the immunobiology of Eimeria species, preventive measures, and the importance of vaccination as a control tool against these Apicomplexan parasites

“…Similar results were documented in studies with other species such as E. necatrix or E. acervulina of chickens and E. meleagrimitis of turkeys. 12 The use of ionophores as effective coccidiostats is welldocumented and has been used for decades. Ionophores act on the sporozoite/merozoite stages of the parasite life cycle, binding to cations and interfering with osmotic potential, thereby disrupting membrane integrity.…”

“…41,42 However, the biochemical basis and the specificity of these compounds to parasites is not clearly elucidated. 12 Studies demonstrate that the parasite dies on absorption of the ionophore in the gut. Monensin, the first polyether ionophore, was introduced in the United States in 1971, and the first evidence of monensin-resistant Eimeria isolate was seen as early as 10 years later.…”

“…4,13 Several underlying mechanisms have been described, and the development of immunity can be stimulated by the deliberate inoculation of oocysts or live parasites that are either wild-type or have been attenuated in the form of vaccines. 12 Immunity can be mediated by the skin, phagocytes, leukocytes, and complement system or by lymphocytes and their secretions, in the form of antibodies and cytokines. 13 The innate immune system interacts with a broad spectrum of pathogens.…”

Effect of the granulometric characteristics of monensin sodium on controlling experimental coccidiosis in broiler chickens

“…While vaccination is today less applied in broiler production, also because of its higher cost, chemoprophylaxis using anticoccidials in the feed is by far the most popular method, insofar as it is estimated that 95% of broilers produced receive anticoccidials (CHAPMAN, 1999).…”

Characterization of Stage-Specific and Cross-Reactive Antigens from Eimeria acervulina by Chicken Monoclonal Antibodies

“…Although the poultry industry has relied upon chemoprophylaxis method to control coccidiosis [7], alternative control strategies are needed due to high costs associated with the development of new drugs [20], rapid emergence of drug resistant field strains of Eimeria [6,12], the public's attitude toward the drug treated-meat products [8,20], the increasing demand for organic products [34] and the disadvantages that accompany the use of live vaccines [20,33]. Therefore, new strategies such as vaccination with recombinant proteins and genetic improvement of poultry immunity, are now actively pursued [22].…”