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United States Department of Agriculture

Agricultural Research Service

Title: Non-invasive methods for identifyig oocysts of Sarcocystis spp. from definitive hosts

item Xiang, Zheng - PD KMC YUNNAN, CHINA
item Chen, Xinwen - DEPT BIO YU YUNNAN,CHINA
item Yang, Lijun - PD KMC YUNNAN, CHINA
item Zhou, Benjiang - PD KMC YUNNAN, CHINA
item Jiang, Runsheng - DHSSUHS KMC YUNNAN,CHINA
item Rosenthal, Benjamin
item Lei, Lin - PD KMC YUNNAN, CHINA
item Luan, Pengtao - LCUB YU KUNMING, CHINA
item Liu, Jiang - LCUB YU KUNMING, CHINA
item Zuo, Yangxian - DEPT BIO YU YUNNAN,CHINA
item Cui, Liwang - PENN STATE UNIV PARK,PA
item Zhang, Ya-Ping - YU CAS KUNMING, PR CHINA
item Yang, Zhaoqing - PD KMC YUNNAN, CHINA

Submitted to: Parasitology International
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 13, 2009
Publication Date: March 29, 2009
Repository URL:
Citation: Xiang, Z., Chen, X., Yang, L., Zhou, B., Jiang, R., Rosenthal, B.M., Lei, L., Luan, P., Liu, J., Attwood, S., Zuo, Y., Cui, L., Zhang, Y., Yang, Z. 2009. Non-invasive methods for identifyig oocysts of Sarcocystis spp. from definitive hosts. Parasitology International. 58(3):293-296.

Interpretive Summary: Many animals, including livestock, contract coccidian infections when they ingest food, or imbibe water, contaminated with oocysts excreted by a carnivore. In only a handful of cases has the carnivore in question has been definitively established for a given parasite, leaving hundreds of others incompletely described. Here, diagnostic genetic features were employed to definitively diagnose the parasites excreted by dogs, cats, and people who were known to have consumed infectious meat. As expected, the genetic signature of each parasite was constant throughout its transmission. Certain improvements are illustrated for the purpose of isolating such oocysts, which should aid future efforts to better 'connect the dots' as such parasites alternate between predator and prey species. Ultimately, this approach will help better define risk factors for animal and public health.

Technical Abstract: Because the excreted sporocysts of various species of Sarcocystis may not be discriminated morphologically, we sought to validate a diagnostic technique based on variation in the 18S rDNA sequence. Oocysts of Sarcocystis hominis, Sarcocystis fusiformis and Sarcocystis cruzi were collected from the feces of their definitive hosts (human, cats, and dogs) using a new method employing filter paper. Corresponding samples were obtained from their intermediate hosts: cattle and water buffalo. These were then distinguished using a PCR-RFLP based method applied to a partial 18S rRNA gene (ssrRNA) sequence. This approach successfully distinguished among the three Sarcocystis taxa when sampled either as tissue cysts or oocysts. The same, unique restriction digestion pattern characterizes the tissue cysts and oocysts of each parasite taxon. The technique can detect 7 sporocysts (the equivalent of 3 and 1/2 oocysts) in fecal samples, making it a potentially useful tool in the identification of Sarcocyst species. To our knowledge, this represents the first report using molecular diagnostic procedures to diagnose oocysts of Sarcocystis in faecal samples.

Last Modified: 7/24/2016
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