Description of Sarcocystis falcatula Stiles, 1893, a Parasite of Birds and Opossums¹

Abstract

Sarcocystis falcatula Stiles, 1893 is re-described. Intermediate hosts of the parasite which was earlier described as Sarcocystis debonei Vogelsang, 1929 are species of passeriform, psittaciform, and columbiform birds. In these birds, muscle zoites are 6.88 X 2.19 (4.8-8.4 X 1.2-3.6) micron and are enclosed in a cyst wall with regular protrusions, 1-5 micron long. The convoluted primary wall has multiple thin areas in the osmiophilic layer. Microtubules originate in the ground substance and extend to the tips of the protrusions. The only known definitive host is the opossum, Didelphis virginiana; rats, cats, a dog, and a ferret could not be infected from muscle cysts. Sporocysts from opossums infected from five different infected avian sources measure 11.2 X 7.4 (9.6-12.0 X 6.0-8.4) micron.

Island and Taxon Effects in Parasitism and Resistance of Lesser Antillean Birds

“…Sarcocystis is known to have a wide avian host range, but transmission between host species evidently requires contact with the ground (Box et al 1984). The distribution of Sarcocystis among potential hosts is consistent with transmission through soil.…”

“…Ecology The island effect for Sarcocystis may reflect the presence on Dominica of a suitable mammalian reservoir for the disease (Box et al 1984), but this idea has not been assessed directly. There is no such ready explanation for the distribution of papilloma virus, but its localization may reflect unique genotypes of the pathogen on Martinique, coupled with broad infectivity across potential hosts.…”

Morphologic characterization of Sarcocystis sp. sarcocysts from the Buffon’s macaw (Ara ambigua)

“…The sarcocyst wall in S. rileyi corresponds to type 21, characterized by cauliflower-like anastomosing villar protrusions (Dubey et al 1989(Dubey et al , 2003. By contrast, the sarcocyst wall in S. falcatula is thick, striated, with finger-like villar protrusions (Drouin and Mahrt 1980;Box et al 1984;Dubey et al 2000Dubey et al , 2001aLuznar et al 2001). The sarcocysts of S. ramphastosi are macroscopic and divided into two distinct zones, whereas the species in the macaw is microscopic.…”

“…Little is known of the species of Sarcocystis in birds, but two avian species have been well characterized: Sarcocystis rileyi cycles between ducks (Anas clypeata, the intermediate host) and the skunk (Mephitis mephitis, the definitive host); Sarcocystis falcatula employs passerine birds as intermediate hosts and the opossum (Didelphis virginianus) as the definitive host (Cawthorn et al 1981;Box et al 1984;Dubey et al 1989Dubey et al , 2003. Two new species, S. ramphastosi and S. sulfuratusi were reported from the keel-billed toucan (Ramphastos sulfuratus) from South Africa by Dubey et al (2004).…”

Sarcocystis Meningoencephalitis in a Northern Gannet (Morus bassanus)

“…In Table 1 the results of PCR coupled with diagnostic restriction digests for S. neurona, S. falcatula, and isolates 1085 and 1086 from a prior study (Tanhauser et al, 1999) (Tanhauser et al, 1999;Rosenthal et al, 2001). The intermediate hosts of S. falcatula appear to involve a wide variety of birds (Box and Smith, 1982;Box et al, 1984). Markers used in this study to characterize the Sarcocystis sp.…”