Sarcocystis rommeli, n. sp. (Apicomplexa: Sarcocystidae) from Cattle (Bos taurus) and its Differentiation from Sarcocystis hominis

Abstract

Cattle (Bos taurus) are intermediate hosts for three named species of Sarcocystis, S. cruzi, S. hirsuta, and S. hominis. Recently, a fourth species was identified and named S. sinensis. However, S. sinensis originally named a species of Sarcocystis in water buffalo (Bubalus bubalis) in China. Based on unverifiable evidence, it was suggested that the same parasite infects cattle. In addition, S. sinensis was recently declared as nomen nudum because its naming violated the rules of International Code of Zoological Nomenclature. Thus, the fourth species using cattle as an intermediate host does not have a valid name. Here, we propose a new name, Sarcocystis rommeli for the S. sinensis-like parasite from cattle in Argentina, and differentiate it ultrastructurally from S. hominis sarcocysts from experimentally infected cattle. Sarcocystis rommeli sarcocysts were microscopic with a 5-μm-thick wall with slender villar protrusions (Vp); the Vp were up to 5 μm long, up to 0.5 μm wide, and of uneven thickness, often bent at an angle. The ground substance layer (Gs) was up to 0.8 μm thick and smooth. Vesicular structures were seen at the base of the Vp. The bradyzoites were 10-12 μm long. Sarcocystis hominis sarcocysts had Vp that were often upright, up to 7.5 μm long, and up to 1.8 μm wide; the Gs was up to 2 μm thick and without vesicles. Its sarcocyst wall was up to 5.6 μm thick, the vp were bent at an angle, up to 5.8 μm long, the Gs was up to 2 μm thick, but without vesicles seen in S. rommeli. Beef containing sarcocysts of S. rommeli was not orally infectious for two human volunteers and a red fox (Vulpes vulpes). The Sarcocystis described here is molecularly different from S. cruzi, S. hirsuta, and S. hominis based on 18S rRNA and cox1 gene sequences.

Sarcocystis heydorni, n. sp. (Apicomplexa: Sarcocystidae) with cattle (Bos taurus) and human (Homo sapiens) cycle

“…Findings related to S. hominis in these calves were reported previously (Dubey et al 1988;Dubey et al 2015a).…”

“…Species of Sarcocystis usually have a two-host, prey-predator life cycle, with herbivores as intermediate hosts and carnivores as definitive hosts (Dubey et al 2015a). The intermediate host becomes infected with Sarcocystis species by ingesting sporocysts excreted in the feces of the definitive host.…”

Fatal Sarcocystis cruzi–induced eosinophilic myocarditis in a heifer in Uruguay

“…Sarcocystis rommeli (formerly misnamed S. sinensis) has also been described infecting cattle; however, its definitive host remains unknown. 5 The species S. bovifelis was proposed instead of S. rommeli based on cyst morphology and the possible role of felids as definitive hosts. 4,7 Morphologically, S. cruzi has thin-walled cysts (<1 μm); cysts of S. hirsuta, S. rommeli, and S. hominis have thicker walls (2-7 μm).…”

Sarcocystis spp. in Romanian Slaughtered Cattle: Molecular Characterization and Epidemiological Significance of the Findings

“…Among them, S. hominis and S. heydorni are human pathogens. Canids act as definitive hosts for S. cruzi and felids for S. hirsuta and S. rommeli [4], while humans or other primates for S. hominis and S. heydorni [2–4]. Of the three genetic markers, only the 18S rRNA gene sequences are available in GenBank for all the five Sarcocystis species known to be responsible for bovine sarcocystosis.…”