Environmental contamination by Eimeria spp. and coccidiosis risk modeling in broiler farms of Medea province, Algeria.

This study assessed environmental contamination by Eimeria spp. in broiler farms in Medea Province, Algeria. A total of 221 composite fecal samples taken from litter, one per farm, were analyzed, revealing oocysts in 42.9% of the farms, with significant variation across districts. The highest contamination frequency was recorded in Beni Slimane (57.1%) and the lowest in Ouamri (19.0%). Oocyst loads, measured in Oocysts Per Gram (OPG), ranged widely, with Beni Slimane showing the highest intensity (21575 OPG). While younger flocks (10-20 days) were associated with the highest oocyst counts (19930 OPG), this age-related trend was not statistically significant. Morphological identification revealed a complex distribution of Eimeria species, dominated by E. tenella (detected in 98.9% of contaminated farms), followed by E. maxima (88.0%) and E. necatrix (78.9%), with mixed-species contamination being common. To conceptually explore the relationship between initial environmental contamination and outbreak risk, a Susceptible-Exposed-Infected-Recovered (SIER) mathematical model was implemented. Model simulations suggested that higher initial levels of environmental oocyst contamination lead to earlier potential peaks in infection within a flock. Lower initial contamination was associated with delayed peaks, theoretically allowing more time for intervention. These findings highlight the critical importance of biosecurity and litter management to reduce the initial environmental oocyst load, thereby mitigating the risk of coccidiosis outbreaks. Proactive monitoring, targeted management strategies, and enhanced awareness among farmers and veterinarians are essential to minimize economic losses and ensure poultry health in the region.