Submitted to: American Association of Veterinary Laboratory Diagnosticians
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/20/2004
Publication Date: 7/20/2004
Citation: Elishieka, H.M., Fitzgerald, S.D., Rosenthal, B.M., Mansfield, L.S. Concurrent presence of Sarcocystis neurona sporocysts, Besnoitia darlingi tissue cysts, and Sarcocystis inghami sarcocysts in naturally infected opossums (Didelphis virginiana). 2004. Journal of Veterinary Diagnostics Investigation. 16(4):352-356. Interpretive Summary: Opossums are the only marsupials endemic to much of North America. As such, their role as reservoirs of parasitic infection raises interesting questions about the degree of fidelity of parasites to the hosts to whom they may have become closely adapted. This question has practical epidemiological significance, since such constraints would insulate livestock from exposure to wildlife pathogens, and would reduce the risk of human infection from animal parasites (zoonoses). Here, the simultaneous infection of individual opossums with three distinct parasites belonging to the Sarcocystidae are reported. Infectoins with the causative agent of Equine Protozoal Myeloencephalitis, Sarcocystis neurona, and tissue cyst infections with an undescribed species of Sarcocystis and with Besnoitia darlingi. Genetic characterization provided by ARS provided a key to the diagnosis of these infections, and build a basis for future characterization of this unique parasite assemblage.
Technical Abstract: Opossums (D. Virgniana) feed on a variety of foods including but not limited to carrion, insects, and nestling birds, exposing them to a wide range of coccidian parasites. Dense D. virginiana populations in urban and suburban areas can be important reservoirs of parasitic infection, given their prolonged fecal shedding of large number of Sarcocystis spp sporocysts (Porter et al. 2001) and their life expectancy of 2-3 years. Here we describe coinfections of Besnoitia darlingi cysts, Sarcocystis neurona sporocysts, and sarcocysts of an unknown species two adult female opossums (Didelphis virginiana) from Michigan. Cysts typical of B. darlingi in gross, histological and ultrastructural characteristics were disseminated throughout the visceral organs, musculature, ears, and skin. Infections of S. neurona and B. darlingi were confirmed by comparative sequence analysis of PCR amplified diagnostic genetic loci. Sarcocysts of an undescribed species of Sarcocystis are also provided. Such ultiple parasitic infections should be considered in the differential diagnosis of tissue forming coccidian protozoa and may have important epidemiological and evolutionary implications.