A survey of Coccidia on 43 poultry farms in Argentina

Fecal samples from 43 broiler and breeder farms in the Entre Rios and Buenos Aires districts of Argentina were examined for Coccidia. Thirty-eight samples were positive by microscopic examination after salt flotation, with counts of 138 to 415,800 oocysts per gram of feces. Samples were aerated for 2 days and inoculated into 21-day-old chicks for determination of prepatent period. Eimeria praecox was conclusively identified in 56% of the samples by producing typical oocysts (17 X 21 mu m) in the feces by 83-90 hr postinoculation (PI). Eimeria mitis was present in 67% of the samples, producing typical oocysts (14 X 15.5 mu m) before 95 hr PI. Typical oocysts of Eimeria maxima (20 X 30 mu m) and/or typical lesions in the midgut upon necropsy 5-6 days PI were present in 42% of the samples. Eimeria tenella was suspected in 24 of 43 samples on the basis of oocyst size but was confirmed in six samples (14%) at necropsy of infected birds with typical lesions in the ceca (hemorrhage, coagulated blood in the lumen, and thickened cecal mucosa). Characteristic lesions of Eimeria acervulina and ovoid oocysts (14 X 18 mu m) were present in all 40 positive samples (93%). Lesions in the lower small intestine of birds inoculated with two of the samples (5%) were typical of Eimeria brunetti. These results confirmed the presence of six species of Coccidia in Argentine poultry (all except Eimeria necatrix, which is known from previous reports) and demonstrated a prevalence and intensity for E. praecox and E. mitis that were previously unreported.