Molecular surveillance of chicken Eimeria species in commercial poultry farms in the Philippines.

Chromist parasites of the genus Eimeria are the causative agent of coccidiosis, an economically important disease of poultry characterized by enteritis, reduced growth performance and decrease in egg production. In the Philippines, Eimeria infections have largely been reported through conventional coproparasitological techniques; however, molecular investigations on the distribution of specific Eimeria species and quantitative assessments of infection intensity are lacking. In the present study, molecular surveillance of Eimeria infections was conducted in various commercial poultry farms in the Philippines to better characterize the epidemiology of the disease. Eimeria oocysts were detected in 24 of 42 poultry houses (57.1%) across 9 of 16 examined commercial farms (56.3%). The positivity rates among different poultry production systems were 60% (6/10) in broilers, 100% (6/6) in broiler breeders; 47.8% (11/23) in layer pullets, 50% (1/2) in egg layers and 0% (0/1) in fighting cocks. The mean oocyst per gram (OPG) across investigated farms was 7211.9 with values ranging from 19.6 to 44,933.3. PCR analysis of the 24 positive poultry houses identified four Eimeria species, namely E. tenella, E. necatrix, E. acervulina, and E. mitis. These findings indicate that Eimeria infections, especially the highly pathogenic species, are widely distributed in commercial poultry operations in the Philippines. The results provide baseline data on the current distribution and infection intensity of Eimeria species in the country, which will be helpful in the prevention, management and control of coccidiosis.