Coccidiosis, caused by the protozoan Eimeria, is one of the most prevalent parasitic threats facing poultry producers today. Taylor Schubauer, a graduate research assistant in the University of Arkansas Poultry Science Department, recently outlined what producers need to understand about this persistent pathogen.
1. It's almost certainly already in your flock
A 2017–2018 study of 64 backyard flocks in Alabama detected Eimeria in more than 60% of samples and in over 64% of flocks. The parasite can be picked up virtually anywhere birds congregate. Complete exclusion is nearly impossible, which makes early recognition and a proactive management plan essential.
2. The economic damage outlasts the outbreak
Watch for rapid weight loss, reduced feed intake, lethargy, ruffled feathers, decreased egg production and high mortality. Birds that survive a severe infection typically never fully recover their production performance. A hen that was laying seven days a week may drop to four or five, negatively impacting productivity and profitability long after the clinical signs resolve.
3. Bleach won't cut it — use ammonia
The oocyst wall that protects Eimeria is highly resistant to most common disinfectants, including bleach. Ammonia is the most effective environmental control agent available. Extreme heat, cold or drought can reduce oocyst viability in outdoor settings, but producers should not rely on environmental conditions alone to clean between flocks.
4. Medicated feed and live vaccines don't mix
Amprolium, the active ingredient in most medicated chick starter, functions as a preventive coccidiostat, not a treatment. Live Eimeria vaccines work by triggering controlled reinfection over approximately three weeks to build lasting immunity. Using both simultaneously can be counterproductive.
5. Not all anticoccidial drugs work the same way
There are two distinct drug mechanisms to understand. Coccidiostats arrest Eimeria development at specific life stages but don't kill the parasite outright. Coccidiocidal drugs go further, killing or irreversibly damaging the parasite across most of its stages. Some drugs do both.
Within those categories, ionophores are fed continuously as a prevention-only measure and must remain uninterrupted to be effective, while chemical options like amprolium are the more familiar option for many producers. Consult a veterinarian to determine which mechanism aligns with your production status as ionophores cannot be used in “no antibiotic ever” production facilities.
6. Rotate your control program to stay ahead of resistance
Commercial producers have long cycled between drug combinations and vaccines across the production calendar to prevent Eimeria from developing resistance to any single approach.
Schubauer noted this strategy is adaptable across production settings and housing types. Work with a veterinarian to build a rotation schedule suited to your flock demographics and regional conditions.
