The role of chicken macrophages in the parenteral excystation of Eimeria acervulina

Abstract

The behaviour of Eimeria acervulina in relation to macrophage activity in chickens was investigated by in vitro and in vivo techniques, with special consideration of the excystation of sporozoites and the fate of intact oocysts and sporocysts inoculated parenterally. In vitro: macrophages obtained from peritoneal washings phagocytosed mechanically released sporocysts or previously excysted sporozoites after 30 minutes incubation. In vivo: phagocytic activity of macrophages against intact oocysts and sporocysts in diffusion chambers implanted subcutaneously and intraperitoneally was observed as early as 4 h after implantation. Changes in the oocyst wall (corrugation, thinning, indentation and increased. fragility) as well as activation and excystation of sporozoites in situ was observed 24 h after implantation. Interaction in vivo between the invasive sporozoite and the phagocytic cell was recorded. Disintegration of the parasite was noticed 72 h after implantation.