de Araujo Larissa S, Gupta Aditya, Papadopoulos Marianne Dias, Naguib Doaa, Battle Jacquin, Kwok Oliver, Khan Asis, Rosenthal Benjamin, Dubey Jitender P
United States Department of Agriculture, Agricultural Research Service, Animal Parasitic Diseases Laboratory, Beltsville Agricultural Research Centre, Beltsville, MD, 20705-2350, USA.
Parasit Vectors. 2025 Feb 1;18(1):35. doi: 10.1186/s13071-025-06660-y.
Bison (Bison bison) and cattle (Bos taurus) are closely related (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.
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.
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.
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.
野牛（美洲野牛）和牛（黄牛）亲缘关系密切（可杂交），且共享许多寄生虫。牛通常感染八种命名的肉孢子虫属物种中的一种或多种：毛肉孢子虫、克鲁斯肉孢子虫、人肉孢子虫、牛猫肉孢子虫、海德肉孢子虫、牛肉孢子虫、西格蒙德肉孢子虫和罗梅尔肉孢子虫。其中，只有克鲁斯肉孢子虫的完整生命周期是已知的。克鲁斯肉孢子虫（通过犬科动物传播）被认为是致病性最强的肉孢子虫物种，可导致流产、产奶量低和身体生长发育不良。它已在实验中实现了牛和野牛之间的交叉传播。
我们检测了来自三个商业来源（农场）的200份野牛肉舌样本（内布拉斯加州141份；南达科他州36份；新泽西州和宾夕法尼亚州23份）。购买冷冻肉舌，使用光学显微镜、组织学和针对克鲁斯肉孢子虫18S核糖体DNA（18S rRNA）的定量PCR（qPCR）检测肉孢子虫感染情况。研究与退化肉孢子虫相关的病变。对组织切片中肉孢子虫感染强度进行定量分析。
在内布拉斯加州的141份肉舌样本中，有129份（91.5%）检测到类似克鲁斯肉孢子虫的感染；南达科他州的36份肉舌样本全部（100%）检测到感染；新泽西州和宾夕法尼亚州的23份肉舌样本中有2份（8.6%）检测到感染。在200份苏木精-伊红染色的组织切片样本中，有167份检测到肉孢子虫。光学显微镜检查显示，肉孢子虫壁薄（<1 µm厚），似乎是克鲁斯肉孢子虫。然而，在两份样本中，肉孢子虫壁较厚，宽达2.3 µm，长154 µm，且肉孢子虫壁无横纹；这两份样本无法进一步鉴定。在三份肉舌样本中，发现了退化的肉孢子虫；其中两份与厚壁肉孢子虫有关。分子检测显示，野牛体内的克鲁斯肉孢子虫与牛体内的相同。
在本次对野牛肉舌的研究中，使用分子和形态学方法在野牛体内鉴定出的唯一物种是克鲁斯肉孢子虫。在两份野牛样本中发现的一种未鉴定的肉孢子虫物种需要进一步研究。
