Oviduct Fluke (Prosthogonimus macrorchis) Found Inside a Chicken Egg in North Carolina

A video received by faculty at North Carolina State University's Prestage Department of Poultry Science revealed a live parasite inside a chicken egg. The parasite was identified as an oviduct fluke (Prosthogonimus macrorchis), a trematode with a three-host life cycle: the primary host, a galliform bird, then an aquatic snail, and finally a dragonfly larva or adult consumed by the infected bird. The egg was from a "backyard flock" with access to a watercourse. No other instances of this parasite were seen in eggs from the flock. The presence of this parasite inside an egg suggests that the worms had migrated above the shell gland in the oviduct to be incorporated inside the egg. Currently, the occurrence of an oviduct fluke inside an egg in the United States is rare. Such parasites are not found in eggs from caged layers because those birds do not have access to watercourses. This case reinforces the view that parasites requiring intermediate hosts may become more common in birds reared under free-range conditions.