Department of Veterinary Preventive Medicine, College of Veterinary Medicine, The Ohio State University, 1920 Coffey Road, Columbus, OH, 43210, USA.
Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, 601 Vernon Tharp Drive, Columbus, OH43210, USA.
BMC Vet Res. 2020 Jan 31;16(1):31. doi: 10.1186/s12917-020-2248-3.
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.
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.
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.
在兽医医学中，检测犬恶丝虫微丝蚴（mf）是一项重要的诊断技能，对第一天的兽医和技术人员至关重要。寻找含有 mf 的血液供应来教授该技术，以及在诊断性显微镜检查中使用的甲醛的不良环境影响，这是一个挑战。
本研究评估了冷冻保存和最近采集的 mf 感染血液以及两种固定剂（乙酸或甲醛）用于 mf 检测的用途。具体目标包括确定兽医学生是否能够 1）使用常规诊断测试检测添加到新鲜血液中的冷冻 mf，以及 2）检测 mf 的形态差异。236 名学生对样本状态保持盲目。比较了评估的样本和固定剂中学生识别 mf 和 mf 形态的能力。结果表明，使用冷冻保存和乙酸的组合来教授微丝蚴诊断技术是可行的；然而，与含有新鲜采集的 mf 的血液相比，mf 形态的质量不如最优。与参考值相比，mf 在评估的每个附加变量下尺寸都减小了。
236 名学生中的大多数（98.3%）正确识别出 mf 的存在。教学实验室可以利用冷冻保存的 mf 感染的供体血液代替从自然或实验感染的狗中采集的新鲜 mf 感染血液。可以使用危害性较小的化学品替代固定剂。最后，尺寸测量的变化提供了一种机制，可以确保学生能够正确测量 mf，因为学生需要进行可验证的测量，并且不能从教科书复制参考值，因为冷冻保存和固定方法会导致 mf 的测量值小于教科书参考值。
