Location: Animal Parasitic Diseases LaboratoryTitle: Sarcocystis heydorni, n. sp. (Apicomplexa: Protozoa) with cattle (Bos taurus) and human (Homo sapiens) cycle
|VAN WILPE, EMA - University Of Pretoria|
|CALER-BERNAL, RAFAEL - Non ARS Employee|
|VERMA, SHIV - Non ARS Employee|
Submitted to: Parasitology Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/23/2015
Publication Date: 8/6/2015
Citation: Dubey, J.P., Van Wilpe, E., Caler-Bernal, R., Verma, S., Fayer, R. 2015. Sarcocystis heydorni, n. sp. (Apicomplexa: Protozoa) with cattle (Bos taurus) and human (Homo sapiens) cycle. Parasitology Research. doi: 10.1007/s00436-015-4645-2.
Interpretive Summary: Zoonosis caused by Toxoplasma, and related parasite Sarcocystis continues to be of public health concern. Sarcocystis is a single celled parasite. Two of the Sarcocystis species, S. hominis and S. suihominis are transmissible to humans by eating raw/undercooked beef or pork, respectively. After ingestion of infected beef or pork humans excrete an environmentally resistant stage (sporocyst) in feces and can suffer from digestive problems (nausea, diarrhea, vomiting). Livestock become infected by ingesting food and water contaminated with sporocysts. ARS scientists now report another new species of Sarcocystis in cattle experimentally infected with sporocysts from human feces. These findings are of public and professional interest.
Technical Abstract: Cattle (Bos taurus) are intermediate hosts for four species of Sarcocystis, S. cruzi, S. hirsuta, S. hominis, and S. rommeli. Of these four species, mature sarcocysts of S. cruzi are thin-walled (< 1µm) whereas S. hirsuta, S. hominis, and S. rommeli have thick walls (4 µm or more). Here we describe a new species of Sarcocystis with thin-walled sarcocysts in cattle. Two newborn calves were fed sporocysts from the feces of a human volunteer who had ingested raw beef. The calves were killed 111 and 222 days later. In addition to thick-walled sarcocysts of Sarcocystis hominis, both calves were coinfected with a Sarcocystis species that had a thin-walled sarcocysts, distinct from Sarcocystis cruzi. The sarcocysts were mature, microscopic, up to 80 µm wide and up to 1060 µm long. By light microscopy, the sarcocyst wall was thin (< 1 µm thick) and had minute protrusions. By transmission electron microscopy, the sarcocyst wall had short, conical villar protrusions (vp), that were up to 0.5 µm long, up to 0.5 µm wide, similar to type 29. The vp on the sarcocyst wall lacked microtubules but had six or more disc-shaped plaques. The ground substance layer was smooth, approximately 0.5 µm thick, and without microtubules. The bradyzoites were 8-11 µm long. The structure of the sarcocyst wall was distinct from any species of Sarcocystis reported from livestock. This unique species is named in honor of Dr. Alfred Otto Heydorn who provided the sporocysts.