Coccidiosis in poultry: Disease mechanisms, control strategies, and future directions

Authors: Jenkins, Mark; MATHIS, GREG - Southern Poultry Research, Inc; LUMPKINS, BRETT - Southern Poultry Research, Inc; CERVANTES, HECTOR - University Of Georgia; FITZ-COY, STEVE - Merck Animal Health; JONES, MATTHEW - Southern Poultry Research, Inc; PRICE, KAYLA - Alltech Biotechnology; DALLOUL, RAMI - University Of Georgia

Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/10/2024
Publication Date: 12/30/2024
Citation: Jenkins, M.C., Mathis, G.F., Lumpkins, B., Cervantes, H.M., Fitz-Coy, S.H., Jones, M.K., Price, K.R., Dalloul, R.A. 2024. Coccidiosis in poultry: Disease mechanisms, control strategies, and future directions. Poultry Science. 104(5). Article e104663. https://doi.org/10.1016/j.psj.2024.104663.
DOI: https://doi.org/10.1016/j.psj.2024.104663

Interpretive Summary: Avian coccidiosis is a parasitic disease of poultry caused by protozoa in the genus Eimeria. The disease causes over $ 1 billion loss each year in the U.S. alone due to lower performance of infected chickens because of poor nutrient uptake in the gut and inefficient feed conversion. An equally problematic issue is the higher mortalities associated with necrotic enteritis which is caused by Clostridium perfringens that exists as a member of the normal flora in healthy chickens, but expands and releases toxins during an Eimeria infection. Additional costs stem from the need to medicate feed with anticoccidial drugs or vaccinate newly hatched chicks with Eimeria oocysts, two ways to prevent outbreaks. While anti-coccidial drugs and live oocyst vaccines have been useful in controlling coccidiosis, the appearance of drug-resistant strains of Eimeria and the introduction of virulent Eimeria into poultry houses by virtue of using live oocysts has prompted the search for alternative means of combating the disease. Molecular techniques are useful in the study and control of avian coccidiosis because one can identify Eimeria species that may be the primary cause of disease outbreaks. Specific treatments (e.g. switching to another anti-coccidial drug) can then be implemented to block replication of this parasite. Although medication of feed with drugs has been and continues to be an important control strategy, vaccination with low doses of Eimeria oocysts is gaining in popularity. One reason is to reduce the use of antibiotics in poultry feed which allows chickens to be grown under antibiotic-free (ABF) conditions. The main obstacle to effective vaccination against avian coccidiosis is ensuring every chick receives sufficient vaccine to withstand Eimeria infection later in life. In this paper, alternative vaccination methods developed in our ARS laboratory using either gelatin bead application to poultry feed or introduction of Eimeria oocysts into the drinking water system of a poultry house exemplifies practical ways to achieve nearly 100% vaccine uptake. Molecular techniques are vital when used in conjunction with Eimeria immunization to measure the effectiveness of any control strategy.

Technical Abstract: According to a 2023 survey by the American Veterinarians in Broiler Production, Coccidiosis is the number one disease in the broiler poultry industry. Coccidiosis results in the reduction of growth rate, decrease in feed efficiency, and poor body weight uniformity. The more we understand this disease the more we can move forward towards control. The purpose of this symposium was to increase our understanding of coccidiosis. The topics discussed were the diagnosis, immune response, control/prevention, medications (natural and chemical), and interactions with other diseases. The Coccidiosis Symposium provided up to date information from both research and field experiences. This information will be useful for production managers, nutritionists, and veterinarians, as well as providing opportunities for future research.