High, but variable prevalence of Sarcocystis cruzi infections in farm-raised American bison (Bison bison) beef destined for human consumption

Authors: DE ARAUJO, LARISSA - Orise Fellow; GUPTA, ADITYA - Orise Fellow; Papadopoulos, Marianne Dia; NAGUIB, DOAA - Orise Fellow; BATTLE, JACQUIN - Orise Fellow; Kwok, Oliver; Khan, Asis; Rosenthal, Benjamin; Dubey, Jitender

Submitted to: Parasites & Vectors
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/3/2025
Publication Date: 2/1/2025
Citation: De Araujo, L.S., Gupta, A., Papadopoulos, M., Naguib, D., Battle, J., Kwok, O.C., Khan, A., Rosenthal, B.M., Dubey, J.P. 2025. High, but variable prevalence of Sarcocystis cruzi infections in farm-raised American bison (Bison bison) beef destined for human consumption. Parasites & Vectors. 18. Article e35. https://doi.org/10.1186/s13071-025-06660-y.
DOI: https://doi.org/10.1186/s13071-025-06660-y

Interpretive Summary: According to the National Agricultural Statistics Service, bison meat production and consumption has increased markedly within the past 5 years in the U.S., owing to its high protein content, low fat content, and taste. Bison and cattle are closely related, can interbreed, and share many parasites. Although cattle are commonly infected with one or more of the 8 named parasitic species in the genus Sarcocystis (some of which can cause human infection), nothing is yet known of such infections in American bison raised for human consumption. Here USDA researchers determined which parasites occur in bison meat and how frequently. They also determined that such parasites pose little public health concern because such meat is typically frozen prior to sale. These findings will be of interest to public health authorities, veterinarians, biologists, and parasitologists.

Technical Abstract: Background Bison (Bison bison) and cattle (Bos taurus) are closely relate (can interbreed) and they also share many parasites. Cattle are commonly infected with one or more of the eight named Sarcocystis species: Sarcocystis hirsuta, S. cruzi, S. hominis, S. bovifelis, S. heydorni, S. bovini, S. sigmoideus and S. rommeli. Among these, the full life-cycle is known only for S. cruzi. Sarcocystis cruzi (transmitted via canids) is recognized as the most pathogenic Sarcocystis species, causing abortion, low milk yield and poor body growth. It has been experimentally cross-transmitted from cattle to bison and vice versa. Methods We tested 200 bison tongues from three commercial sources (farms) (Nebraska #141; South Dakota #36; New Jersey and Pennsylvania #23). Frozen tongues were purchased and examined for Sarcocystis infection using light microscopy, histology and quantitative PCR (qPCR) targeting 18S ribosomal DNA (18S rRNA) of S. cruzi. Lesions associated with degenerating sarcocysts were studied. The intensity of Sarcocystis infection in histological sections was quantitated. Results Sarcocystis cruzi-like infections were detected in 129 of 141 (91.5%) tongues from Nebraska, 36 of 36 (100%) tongues from South Dakota and two of 23 (8.6%) tongues from New Jersey and Pennsylvania. Sarcocysts were detected in histological sections stained with hematoxylin and eosin in 167 of 200 samples. Light microscopy examination revealed that the sarcocysts had thin walls (< 1 µm thick) and appeared to be S. cruzi. However, in two samples, sarcocysts had thicker walls measuring up to 2.3 µm wide and 154 µm long and the sarcocyst wall was not striated; these two samples could not be characterized further. In three tongues, degenerating sarcocysts were recognized; two of these were associated with thick-walled sarcocysts. Molecularly, S. cruzi from bison was identical to that in cattle. Conclusions In the present study of bison tongues, S. cruzi was the only species identified in bison using both molecular and morphological methods. An unidentified species of Sarcocystis found in two bison samples needs further study.