Eimeria stiedae in domestic rabbits (Oryctolagus cuniculus) farmed in agroecological and industrial systems in Argentina

Abstract

Health in commercial and domestic rabbit farming is commonly affected by rabbit coccidiosis. For this study, 90 crossbreed rabbits (New Zealand x Californian) of 2.7–5 months of age and 1.5–2.5 kg from agroecological (n = 11) and industrial (n = 79) systems were slaughtered for consumption. Bile and liver samples were collected, filtered, and dissolved in potassium dichromate and distilled water for oocyst sporulation. Additionally, liver tissue samples fixed in 10 % buffered formalin were analysed for histopathological diagnosis. The overall prevalence of E. stiedae was observed in 24.4 % (22/90) of the liver samples. The prevalence in the agroecological system was 72.7 % (8/11) and 17.7 % (14/79) in the industrial system. In 27.2 % (6/22) bile vesicles, after a puncture, non-sporulating oocysts were observed in the interior, coinciding with those livers with hepatomegaly and a greater number of yellowish-white nodules, scattered for the surface and in the interior. Mild hepatomegaly was observed, with irregular yellowish-white nodules of varying sizes in all liver lobes, containing white caseous material with non-sporulating oocysts. The gall bladder was distended (3.5 cm) with yellowish fluid. Histopathological analysis showed dilated bile ducts due to extensive epithelial proliferation and hyperplasia, with abundant necrotic contents and detached biliary epithelial cells, alongside thick-walled non-sporulating oocysts in the duct lumen. Sequence analysis showed 98.4 % homology with rabbit E. stiedae 18S generic primers and the sequences deposited in GenBank such as (PQ427813). The sequence analysis obtained from the ITS1 product showed 92.2–93.4 % homology with rabbit E. stiedae. This report describes the natural infection of E. stiedae in rabbit liver from the agroecological and industrial system by morphology, histopathology, and molecular confirmation in Argentina. Our results could contribute to the diagnosis of E. stiedae infection in rabbits in Argentina.