ARS | Publication request: DETECTION OF SARCOCYSTIS PARASITES IN RETAIL BEEF: A REGIONAL SURVEY COMBINING HISTOLOGICAL AND GENETIC DETECTION METHODS

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 2, 2008
Publication Date: October 1, 2008
Citation: Pritt, B., Trainer, T., Simmons-Arnold, L., Evans, M., Dunams, D.B., Rosenthal, B.M. 2008. Detection of sarcocystis parasites in retail beef: a regional survey combining histological and genetic detection methods. Jrnl of Food Protection. 71 (10): pp. 2144-2147(4).

Interpretive Summary: Sarcocystis are parasitic protists acquired when undercooked cyst-laden meat is consumed. While both S. hominis and S. cruzi encyst in beef, only S. hominis is pathogenic to humans. In this study, we used histological methods and novel molecular techniques to determine the regional prevalence and identity of Sarcocystis spp. in retail beef. We found no occurrences of a parasite, S. hominis, known to infect people in Asia. Instead, the parasite that we found prevalent in US beef was one posing no known risk to human health.

Technical Abstract: Of 112 specimens, 61 supported amplification of parasite ribosomal RNA by PCR. All sequenced representatives were identified as representing S. cruzi and not as S. hominis. Of the 50 cases examined in parallel by each method, histological sections and molecular amplification were positive in 18 and 27 cases respectively. Infection was detected by neither assay in 17 specimens. Six cases identified histologically were not amplified by PCR, whereas 15 amplified cases did not contain sarcocysts on initial section. Deeper sections revealed sarcocysts in an additional 12 cases. We found no evidence of S. hominis in this regional sample of US retail beef. We confirm that S. cruzi is highly prevalent in retail beef and find that PCR assays may increase the detection sensitivity of this bovine infection and contribute diagnostic precision.