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Submitted to: Miscellaneous Publishing Information Bulletin
Publication Type: Review Article Publication Acceptance Date: 5/10/2004 Publication Date: 6/21/2004 Citation: Jenkins, M.C. 2004. Control of avian coccidiosis: drugs and vaccines. Miscellaneous Publishing Information Bulletin. Feed Information News Service, p. 3. Interpretive Summary: Diseases caused by viruses, bacteria, or parasites continue to plague the poultry industry. The growth of the worldwide poultry industry over the last half-century has been due in part to the use of measures to prevent and control these diseases. Avian coccidiosis has been controlled during this time by the addition of anticoccidial compounds (synthetic drugs or ionophores) to poultry feed. Without adequate control measures, this intestinal disease can wreak havoc in a poultry facility causing poor weight gain and feed utilization in affected chickens. Outbreaks of coccidiosis occur in broilers primarily because of confined housing conditions and because the transmission stage (oocysts) of the parasite remains infectious for months after being shed by infected birds. While immunity probably plays some role in limiting coccidiosis, past and current control of these parasites has relied mostly on medication of feed with anticoccidial compounds. The reason drugs have been so successful is that they are generally effective against all species of coccidia. A number of compounds have been and are currently being used to control this disease. The use of a particular drug may be discontinued if it is no longer effective in controlling coccidiosis due to the appearance of drug-resistant strains of Eimeria. The poultry industry facing repeated drug resistance, the lack of new anti-coccidial compounds, and consumer pressure to decrease antibiotics in animal feed, will be forced to seek alternative strategies to control avian coccidiosis. One strategy that has been used to limited extent for several decades is vaccination with live Eimeria oocysts. This approach is based on the well-documented protective immunity that develops in chickens after a primary coccidial infection. At least 9 different live oocyst vaccines are available on a commercial basis. In preliminary studies, these vaccines have proven equal to drugs in controlling outbreaks of coccidiosis. Technical Abstract: The growth of the worldwide poultry industry over the last 50 years is due in part to the use of medicated feed to control avian coccidiosis. Without adequate control measures, this intestinal disease can wreak havoc in a poultry facility causing poor weight gain and feed utilization in affected chickens. Outbreaks of coccidiosis occur in broilers primarily because of confined housing conditions and because the transmission stage (oocysts) of the parasite remains infectious for months after being shed by infected birds. While immunity probably plays some role in limiting coccidiosis, past and current control of these parasites has relied mostly on medication of feed with anticoccidial compounds. The reason drugs have been so successful is that they are generally effective against all species of coccidia. A number of compounds have been and are currently being used to control this disease. The use of a particular drug may be discontinued if it is no longer effective in controlling coccidiosis due to the appearance of drug-resistant strains of Eimeria. The poultry industry facing repeated drug resistance, the lack of new anti-coccidial compounds, and consumer pressure to decrease antibiotics in animal feed, will be forced to seek alternative strategies to control avian coccidiosis. One strategy that has been used to limited extent for several decades is vaccination with live Eimeria oocysts. This approach is based on the well-documented protective immunity that develops in chickens after a primary coccidial infection. At least 9 different live oocyst vaccines are available on a commercial basis. In preliminary studies, these vaccines have proven equal to drugs in controlling outbreaks of coccidiosis. |
