Submitted to: Journal of Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 30, 2001
Publication Date: N/A
Interpretive Summary: Sarcocysts falcatula is a single-celled parasite of birds. It causes fatal pneumonia in certain species of birds, especially in zoos. The Virginia opossum (Didelphis virginiana) is the main reservoir of this parasite in North America. Scientists at the Beltsville Agricultural Research Center and the University of Sao Paulo, Brazil have found the same parasite in another host, Didelphis marsupialis. These findings will be of interest to parasitologists, biologists, and pathologists.
Isolates of Sarcocystis falcatula-like organisms from South American opossums were characterized based on biological and morphological criteria. Sporocysts from intestinal scrapings of 1 Didelphis marsupialis and 8 Didelphis albiventris from S o Paulo, Brazil were fed to captive budgerigars (Melopsittacus undulatus). Budgerigars fed sporocysts from all 9 isolates became ill and S. falcatula-like schizonts were identified in sections of their lungs by immunohistochemical staining. Sarcocystis falcatula-like organisms were cultured from lungs of budgerigars fed sporocysts from the D. marsupialis, and from lungs of budgerigars fed sporocysts from 3 of 8 D. albiventris. The 33/54 locus amplified by PCR from culture-derived merozoites contained both a Hinf I endonuclease recognition site previously suggested to diagnose S. falcatula and also a Dra I site thought to diagnosed S. neurona.. Development of the isolate from D. marsupialis was studied in cell culture; its schizonts divided by endopolygeny, leaving a residual body. Morphological and genetic variation differentiated this Sarcocystis isolate originating in D. marsupialis from the Cornell 1 isolate of S. falcatula. This is the first report of a S. falcatula infection in the South American opossum, D. marsupialis.