The Initiation of Avian Coccidial Infection with Merozoites

The difficulty of separating Eimeria necatrix from E. tenella when the oocysts of both species are present in the ceca, led the writer to investigate the possibility of infecting chickens with merozoites. The only clear-cut evidence demonstrating the transmission of coccidial infection with merozoites was presented by Roudabush (1935) who infected rats with the merozoites of E. miyairii. Andrews' report (1927) of successful transmission of Isospora felis to a cat by feeding merozoites is open to some question since he did not eliminate the possibility of sporozoites being present along with the merozoites. Tyzzer (1929), despite repeated attempts, failed to infect chickens with E. tenella by cloacal injections of merozoites.