Strain variations within Eimeria meleagrimitis from the turkey.

During the course of a field study of coccidiosis in turkeys, Eimeria oocysts were found which had much smaller dimensions that any previously recorded isolate from the turkey. These oocysts were purified by single oocyst infection of a turkey. The first oocysts (mean dimensions 16-15 X 14-75 micrometer) were recovered 103 h later. Inoculation of between 0-5 and 2-5 X 10(5) oocysts of this isolate caused severe effects on body weight gain. Cross-immunity studies showed the parasite to be a strain of E. meleagrimitis. Electrophoretic analyses of two enzymes showed that the strain could be differentiated from another strain of E. meleagrimitis (Weybridge strain B). The results show that strain variation occurs within the species E. meleagrimitis and extreme caution should be used in identifying species of Eimeria from the turkey by the oocyst characters.