Author
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Danforth, Harry |
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Submitted to: International Journal for Parasitology
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 4/10/1998 Publication Date: N/A Citation: N/A Interpretive Summary: The U.S. poultry industry has annual losses of over $350 million due to coccidiosis, an intestinal disease caused by the intracellular protozoan parasites, the coccidia. This disease has been controlled by use of anticoccidial compounds, but the increased incidence of drug resistance by the parasites has dictated that another avenue of control be investigated. In a series of experiments and field trial studies, done in collaboration with vaccine and pharmaceutical companies, it was found that viable oocyst vaccine immunization would give significant protection against coccidial infection resulting in improved bird weight and flock feed efficiency. These studies found that: 1) the new high production strains of birds used by the poultry industry could be successfully immunized using oocyst vaccines; 2) a gel-delivery system would give better immunization of birds; 3) reformulation of oocyst vaccines to include strains from the local geographical area in which the vaccine was to be used was sometimes necessary to ensure adequate protection; and 4) combined use of oocyst vaccination and anticoccidial drug medication would give increased bird flock performance. These results have given the poultry industry another direction in anticoccidial control. Technical Abstract: Areas addressed in this study of the use of live oocyst vaccines to control coccidiosis include: the influence of immunocompetency of the strains and sex of the birds used; methods of delivery of vaccine; immunological variation between different strains of the same coccidial species; and the effects of combining vaccine with anticoccidial medication. The results show that vaccination with live oocysts elicited significant protection against coccidiosis, both with experimentally induced and naturally acquired coccidial infection, resulting in average bird weight gains and feed efficiency similar to that obtained with conventional anticoccidial medication. |
