Nine Eimeria species have been described for chickens, but only 7 species are commonly associated with disease; these include E. acervulina, E. brunetti, E. maxima, E. tenella, E. necatrix, E. praecox, and E. mitis.
Oocysts sporulate quickly once in the environment; daily removal of feces can aid in the prevention of coccidiosis. After they are infective, oocysts are resistant to most commonly used disinfectants. Infective oocysts can survive for many months in the environment. Sporulation occurs rapidly (<16 hours) at temperatures between 30° C and 37° C. Sporulated oocysts are resistant to adverse environmental conditions and can survive as long as one year in moist, protected environments if they are not exposed to freezing or extremely high temperatures.