不同犬血中犬恶丝虫微丝蚴检测方法的比较性能分析。
Comparative performance analysis of different microfilaria testing methods for Dirofilaria immitis in canine blood.
机构信息
Department of Veterinary Pathobiology, Oklahoma State University College of Veterinary Medicine, Stillwater, OK, USA.
Kansas State University College of Veterinary Medicine, Manhattan, KS, USA.
出版信息
Parasit Vectors. 2024 Nov 11;17(1):460. doi: 10.1186/s13071-024-06537-6.
BACKGROUND
Microfilaria (MF) testing is an essential part of canine heartworm diagnostics, and it is recommended by the American Heartworm Society that a MF test be performed in tandem with antigen testing on every dog, every year, regardless of prevention status or history. There are a variety of methods that can be used to detect MF in canine whole blood; however, these methods widely vary in their sensitivities as well as practical factors, including time investment and cost. Additionally, some MF tests offer the advantage of being quantitative or allowing for morphological or molecular species identification, while other tests should only be used qualitatively.
METHODS
The purpose of this study is to evaluate the quantitative and qualitative performance of MF tests, including the 20 μL count, wet mount, 9 μL and 40 μL hematocrit tubes, thin smear, thick smear, modified Knott test (MKT), and conventional polymerase chain reaction (PCR).
RESULTS
Qualitatively, there was little difference in the performance of the 20 μL count, wet mount, MKT, and PCR. The MKT and PCR are the optimal MF tests, as these perform most reliably for detecting positives even when the MF per milliliter is relatively low, and in most cases, these two methods also allow for species-level confirmation of the identity. However, PCR tends to be a very costly test, and both PCR and MKT require a greater degree of expertise and time investment to perform than other tests. Even the lowest performance tests, including the thin smear and hematocrit tube methods, can reliably detect MF at very high burdens; although, caution should be advised when using low reliability methods, since there is a greater likelihood of failing to identify MF-positive dogs.
CONCLUSIONS
Microfilaria (MF) testing is an essential part of heartworm diagnosis and screening in dogs, and test selection should balance practical factors such as cost and time investment with the patient's risk of infection based on prevention status and history, clinical signs, and antigen testing results. This approach to MF testing will help minimize cost while avoiding failure to detect MF in infected dogs, especially when MF burden is low.
背景
微丝蚴（MF）检测是犬心丝虫诊断的重要组成部分，美国心丝虫学会建议每年对每只狗进行 MF 检测和抗原检测，无论其预防状况或病史如何。有多种方法可用于检测犬全血中的 MF，但这些方法在敏感性以及实际因素（包括时间投入和成本）方面差异很大。此外，一些 MF 检测具有定量或允许形态或分子种鉴定的优势，而其他检测只能定性使用。
方法
本研究旨在评估 MF 检测的定量和定性性能，包括 20 μL 计数、湿片、9 μL 和 40 μL 红细胞压积管、薄涂片、厚涂片、改良 Knott 试验（MKT）和常规聚合酶链反应（PCR）。
结果
定性方面，20 μL 计数、湿片、MKT 和 PCR 的性能差异不大。MKT 和 PCR 是最佳的 MF 检测方法，因为即使 MF 每毫升相对较低，这些方法也能最可靠地检测出阳性，并且在大多数情况下，这两种方法还允许对身份进行种级别的确认。然而，PCR 往往是一种非常昂贵的检测方法，PCR 和 MKT 比其他检测方法需要更多的专业知识和时间投入。即使是性能最低的检测方法，包括薄涂片和红细胞压积管方法，也可以可靠地检测到非常高的 MF 负担；尽管如此，在使用低可靠性方法时应谨慎，因为识别 MF 阳性狗的可能性更大。
结论
MF 检测是犬心丝虫诊断和筛查的重要组成部分，检测方法的选择应根据预防状况和病史、临床症状和抗原检测结果，在成本和时间投入等实际因素与患者的感染风险之间取得平衡。这种 MF 检测方法有助于降低成本，同时避免漏检感染犬的 MF，尤其是当 MF 负担较低时。
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