BACKGROUND Detection of D. immitis microfilaria (mf) is an important diagnostic skill in veterinary medicine and is critical to Day 1 veterinarians and technicians. Finding a supply of blood containing mf to teach the technique and formalin's adverse environmental effects used in the diagnostic microscopic tests present a challenge. RESULTS This study evaluated the use of cryopreserved and recently drawn mf-infected blood along with two fixative reagents, acetic acid or formalin for mf detection. The specific aims included determining if veterinary students could 1) detect cryopreserved mf added to fresh blood using routine diagnostic testing and 2) detect morphological differences in the mf. The 236 students were kept blind from the sample status. The ability of the students to identify mf and the mf morphology were compared for the samples and fixatives evaluated. The results demonstrate using a combination of cryopreservation and acetic acid for teaching microfilaria diagnostic techniques is fleasible; however, the quality of the mf morphology is less than optimal when compared to freshly acquired mf containing blood. Compared to reference values, the mf demonstrated a decrease in size with each additional variable evaluated. CONCLUSION A majority (98.3%) of the 236 students correctly identified the presence of mf. Teaching laboratories could utilize cryopreserved mf-spiked donor blood in lieu of freshly collected mf-containing blood from a naturally or experimentally infected dog. Substitution of less hazardous chemicals for the fixative can be used. Finally, the change in size measurements provides a mechanism to ensure students can correctly measure mf as students are required to do verifiable measurements and cannot copy reference values from a text book since the cryopreservation and fixation methods cause the mf to measure smaller than textbook reference values.

中文翻译：

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微丝蚴冷冻和固定用于学生指导和临床寄生虫学技能评估的可行性和比较分析。

背景检测 D. immitis 微丝蚴 (mf) 是兽医学中一项重要的诊断技能，对第 1 天的兽医和技术人员至关重要。寻找含有 mf 的血液供应来教授用于诊断显微镜测试的技术和福尔马林对环境的不利影响是一项挑战。结果 本研究评估了冷冻保存和最近抽取的受 mf 感染的血液以及两种固定试剂醋酸或福尔马林用于 mf 检测的用途。具体目标包括确定兽医学生是否可以 1) 使用常规诊断测试检测添加到新鲜血液中的冷冻保存的 mf 和 2) 检测 mf 的形态差异。236 名学生对样本状态视而不见。对于评估的样品和固定剂，比较了学生识别 mf 和 mf 形态的能力。结果表明，在教授微丝蚴诊断技术时结合使用冷冻保存和醋酸是可行的；然而，与新鲜获得的含有血液的 mf 相比，mf 形态的质量并不理想。与参考值相比，mf 在评估每个附加变量时显示出尺寸减小。结论 236 名学生中的大多数 (98.3%) 正确识别了 mf 的存在。教学实验室可以使用冷冻保存的加有 mf 的供体血液来代替从自然或实验感染的狗身上新鲜收集的含 mf 的血液。可以使用危害较小的化学物质代替固定剂。最后，