Cyathostomins are pervasive parasites of equids across the world. Larval stages encyst in the mucosa of the cecum, ventral and dorsal colon and can induce an inflammatory response leading to larval cyathostominosis, a life-threatening generalized typhlocolitis. Mucosal digestion is the only gold standard procedure for identifying and quantifying all larval stages. There is a lack of standardization of this technique and several aspects are ambiguous, such as precision of the method and the possibility of spatial variation of mucosal larval counts. The aim of this study was to estimate precision for enumeration of early third stage larvae (EL3) and late third stage/fourth stage (LL3/L4) larvae and investigate spatial variation of encysted counts within large intestinal organs. Six naturally infected and untreated horses aged 2–5 years were euthanized as part of an anthelmintic efficacy study, and the cecum (Cec), ventral colon (VC) and dorsal colon (DC) were collected. Each organ was rinsed, weighed, and visually separated into 3 equally sized sections. Two 5% tissue samples were collected from each section, a total of six replicates per organ. The mucosae were digested, and 2% examined under the microscope for presence of EL3 and LL3/L4 stage larvae. Overall, 59 % of the harvested larvae were EL3s, and 41 % were LL3/L4s. The ventral colons represented 45 % of the total organ weight, and contributed 37 and 41 % of the EL3s and LL3/L4s harvested, respectively. The Cec, representing only 27 % of the weight contributed 23 % of EL3s and 47 % of LL3/L4s. The DC represented 28 % of the total organ weight, and 28 % and 12 % of the total EL3s and LL3/L4s, respectively. Coefficients of variation varied from 33 to 183 % for EL3 counts and 38–245% for LL3/L4 counts. There were no statistically significant associations between EL3 counts and either organ or location. For LL3/L4 counts there were no statistically significant differences between the three locations within organs (p = 0.1166), but the DC had significantly lower counts than the other two organs (p < 0.0001). Increasing the number of mucosal replicates from each organ improved estimation, but required a considerably increased workload. In conclusion, mucosal larval cyathostomin counts are highly variable, complicating their use for treatment efficacy estimation.

Cyathostomins 是世界各地马科动物的普遍寄生虫。幼虫阶段在盲肠、腹侧和背侧结肠的粘膜中形成包囊，可诱发炎症反应，导致幼虫 cyathostominosis，这是一种危及生命的全身性斑疹伤寒结肠炎。粘膜消化是识别和量化所有幼虫阶段的唯一金标准程序。该技术缺乏标准化，并且有几个方面不明确，例如方法的精度和粘膜幼虫计数空间变化的可能性。本研究的目的是估计早期第三阶段幼虫 (EL3) 和晚期第三阶段/第四阶段 (LL3/L4) 幼虫的计数精度，并研究大肠器官内包囊计数的空间变化。作为驱虫药效研究的一部分，六匹自然感染且未经治疗的 2-5 岁马被安乐死，并收集了盲肠 (Cec)、腹侧结肠 (VC) 和背侧结肠 (DC)。冲洗每个器官，称重，并在视觉上分成 3 个相同大小的部分。从每个切片收集两个 5% 的组织样本，每个器官总共六次重复。消化粘膜，并在显微镜下检查 2% 的 EL3 和 LL3/L4 阶段幼虫的存在。总的来说，59% 的收获幼虫是 EL3s，41% 是 LL3/L4s。腹侧结肠占器官总重量的 45%，分别占收获的 EL3 和 LL3/L4 的 37% 和 41%。仅占重量 27% 的 Cec 贡献了 23% 的 EL3 和 47% 的 LL3/L4。DC 占总器官重量的 28%，分别占全部 EL3 和 LL3/L4 的 28% 和 12%。EL3 计数的变异系数为 33% 至 183%，LL3/L4 计数的变异系数为 38-245%。EL3 计数与器官或位置之间没有统计学上的显着关联。对于 LL3/L4 计数，器官内三个位置之间没有统计学上的显着差异 (p = 0.1166)，但 DC 的计数显着低于其他两个器官 (p < 0.0001)。增加每个器官的粘膜复制数量可以改善估计，但需要显着增加的工作量。总之，粘膜幼虫 cyathostomin 计数变化很大，使它们用于治疗疗效评估变得复杂。EL3 计数的变异系数为 33% 至 183%，LL3/L4 计数的变异系数为 38-245%。EL3 计数与器官或位置之间没有统计学上的显着关联。对于 LL3/L4 计数，器官内三个位置之间没有统计学上的显着差异 (p = 0.1166)，但 DC 的计数显着低于其他两个器官 (p < 0.0001)。增加每个器官的粘膜复制数量可以改善估计，但需要显着增加的工作量。总之，粘膜幼虫 cyathostomin 计数变化很大，使它们用于治疗疗效评估变得复杂。EL3 计数的变异系数为 33% 至 183%，LL3/L4 计数的变异系数为 38-245%。EL3 计数与器官或位置之间没有统计学上的显着关联。对于 LL3/L4 计数，器官内三个位置之间没有统计学上的显着差异 (p = 0.1166)，但 DC 的计数显着低于其他两个器官 (p < 0.0001)。增加每个器官的粘膜复制数量可以改善估计，但需要显着增加的工作量。总之，粘膜幼虫 cyathostomin 计数变化很大，使它们用于治疗疗效评估变得复杂。对于 LL3/L4 计数，器官内三个位置之间没有统计学上的显着差异 (p = 0.1166)，但 DC 的计数显着低于其他两个器官 (p < 0.0001)。增加每个器官的粘膜复制数量可以改善估计，但需要显着增加的工作量。总之，粘膜幼虫 cyathostomin 计数变化很大，使它们用于治疗疗效评估变得复杂。对于 LL3/L4 计数，器官内三个位置之间没有统计学上的显着差异 (p = 0.1166)，但 DC 的计数显着低于其他两个器官 (p < 0.0001)。增加每个器官的粘膜复制数量可以改善估计，但需要显着增加的工作量。总之，粘膜幼虫 cyathostomin 计数变化很大，使它们用于治疗疗效评估变得复杂。