Monitoring Avian Coccidiosis Incidence in Broiler Farms in Brazil: Integrating Eimeria sp. Lesion Scoring with Direct Micro-Quantification of E. maxima Oocysts

ABSTRACT Avian coccidiosis, caused by Eimeria protozoan parasites, inflicts significant economic losses to the poultry industry. The host-species specificity and the resilient nature of Eimeria oocysts demand efficient prophylactic and therapeutic management programs. To enhance control strategies, several metric indices are used to measure the level of coccidial infection, but serious challenges exist in their applicability and interpretation in commercial settings. A combination of lesion scores (LS) and direct micro-quantification of E. maxima oocyst (Micro-q Em) in the broiler gastrointestinal tract offers a comprehensive approach to understanding the population dynamics of Eimeria species during the broiler rearing period (RP). One hundred and three integrated broiler companies in various states of Brazil over a ten-year period (2012-2022) were sampled, in a longitudinal study that included 8,423 broiler chicks aged from 14 to 42 days. The results indicated differences in Eimeria sp. LS and Micro-q Em incidence throughout the RP. E. acervulina exhibited a prevalence of 56.4%, E. maxima 28.0%, and E. tenella 15.6%. The LS of E. maxima showed an unexpected peak of incidence at the beginning and end stages of the RP, while the LS of E. acervulina displayed a prevalence in the epidemiological coccidiosis curve after 32 days of age, suggesting an extraordinary dynamic oocysts reproduction. A very strong correlation (0.958) was observed between the LS of Eimeria sp. and Micro-q Em scoring. This monitoring strategy offered useful information for the accurate incidence analysis of Eimeria species throughout the RP. These findings help optimize control methods for unexpected outbreaks of Eimeria infections at the farm level in Brazil.