Submitted to: Journal of Eukaryotic Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 26, 2001
Publication Date: N/A
Interpretive Summary: Parasites of the genus Sarcocystis are single-celled organism that infect livestock and human beings. Sarcocystis has a 2-host prey (herbivore) and predator (carnivore) lifecycle. Opossums are reservoir hosts for at least 3 species of Sarcocystis, S. neurona, S. speeri, and S. falcatula and all of them can cause death in animals. Scientists at the Beltsville Agricultural Research Center report a new species, Sarcocystis lindsayi from the feces of an opossum. These results will be of interest to biologists, parasitologists and pathologists.
A new species, Sarcocystis lindsayi is proposed for a parasite resembling Sarcocystis falcatula obtained from the lungs and muscles of budgerigars (Melopsittacus undulatus) fed sporocysts from a naturally-infected South American opossum, Didelphis albiventris, from Jaboticabal, Brazil. Sarcocysts of S. lindsayi in budgerigars are microscopic, up to 600 m long and up to 50 m wide. The cyst wall is up to 2 m thick. Ultrastructurally, the sarcocyst wall consists of numerous slender villar protrusions (up to 2.0 m long and up to 0.3 m wide), each with a stylet at its tip. Schizonts in cell culture divide by endopolygeny leaving a residual body. Sporocysts are ~ 12 x 7 m. The parasite is genetically distinct from other organisms that also cycle between opossums and avian species and resemble S. falcatula. Diagnostic genetic variation has been observed in the nuclear Large Subunit Ribosomal RNA gene, the Internal Transcribed Spacer (ITS-1), and each of two other genetic loci. Although the structure of the sarcocyst wall may not provide sufficient grounds for differential diagnosis, several other attributes including schizont morphology and genetic variation at each of three genetic loci permit S. lindsayi identification. Natural intermediate hosts for S. lindsayi are not known, and fuller characterization of these and other Sarcocystis species would benefit from experimental avian hosts that are more permissive to the maturation of sarcocysts.