Submitted to: International Journal for Parasitology
Publication Type: Review Article
Publication Acceptance Date: 9/9/1999
Publication Date: N/A
Citation: Interpretive Summary: The single-celled parasite Toxoplasma gondii and Neospora caninum are closely related parasites. Both can cause abortion in livestock. Differential diagnosis of these parasites in histologic sections is difficult. Scientists at the Beltsville Agricultural Research Center and the Montana State University describe in detail ultrastructure of tissue cysts and tachyzoites of N. caninum and compare them with ultrastructure o T. gondii. These results will be of use to parasitologists, pathologists, and biologists.
Technical Abstract: The ultrastructure of tachyzoites, bradyzoites and tissue cysts of the NC-1 and NC-Liverpool strains of Neospora caninum were compared with those of the VEG and ME-49 strains of Toxoplasma gondii. While each stage of N. caninum and T. gondii shared many ultrastructural characteristics, each parasite stage also had certain features or organelles that could be used to distinguish the two parasites. Some of the most prominent ultrastructural differences occurred in the number, appearance and location of rhoptries, looped-back rhoptries, micronemes, dense granules, small dense granules and micropores. The tissue cysts of both parasites were also basically similar being surrounded by a cyst wall and not compartmentalized by septa. The cyst wall of N. caninum was irregular and substantially thicker, 0.5-4 æm, than those of T. gondii which were smooth and 0.5 æm thick.