Infectious Diseases Pathology Branch, Division of High-Consequence Pathogens and Pathology, Centers for Disease Control and Prevention, Atlanta, Georgia.
Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia.
Am J Trop Med Hyg. 2024 Jun 4;111(1):51-58. doi: 10.4269/ajtmh.23-0387. Print 2024 Jul 3.
Leishmaniasis is an important travel-related parasitic infection in the United States. Treatment regimens vary by Leishmania species and require an accurate diagnosis. The sensitivity and specificity of diagnostic methods depend on the type and condition of specimen analyzed. To identify the best algorithm for detection of parasites in fresh and fixed tissue samples, we evaluated parasite cultures, two PCR methods, and Leishmania immunohistochemistry (IHC) in samples received by the CDC from 2012 through 2019. The sensitivity and specificity of IHC assays were evaluated in fresh specimens tested. Diagnostic accuracy for formalin-fixed tissue was evaluated by using PCR-based methods and IHC. Of 100 suspected cases with fresh tissue available, Leishmania spp. infection was identified by PCR in 56% (56/100) of specimens; from these, 80% (45/56) were positive by parasite culture and 59% (33/56) by IHC. Of 420 possible cases where only fixed specimens were available, 58% (244/420) were positive by IHC and/or PCR. Of these, 96% (235/420) were positive by IHC and 84% (204/420) by PCR-based methods. Overall parasite detection using all methodologies was similar for fresh and formalin-fixed tissue specimens (56% versus 58%, respectively). Although PCR-based methods were superior for diagnosis of leishmaniasis and species identification in fresh samples, IHC in combination with PCR increased the accuracy for Leishmania spp. detection in fixed samples. In conclusion, PCR is the most effective method for detecting Leishmania infection in fresh tissue samples, whereas for formalin-fixed samples, IHC and PCR-based methods should be used in combination.
利什曼病是美国一种重要的与旅行相关的寄生虫感染。治疗方案因利什曼原虫物种而异，需要准确诊断。诊断方法的敏感性和特异性取决于分析标本的类型和状况。为了确定检测新鲜和固定组织样本中寄生虫的最佳算法，我们评估了寄生虫培养、两种 PCR 方法和利什曼免疫组化（IHC）在 2012 年至 2019 年期间由 CDC 收到的样本中的应用。评估了新鲜标本中 IHC 检测的敏感性和特异性。通过基于 PCR 的方法和 IHC 评估了福尔马林固定组织的诊断准确性。在 100 例有新鲜组织的疑似病例中，PCR 在 56%（56/100）的标本中检测到利什曼原虫属感染；其中，80%（45/56）的标本通过寄生虫培养阳性，59%（33/56）的标本通过 IHC 阳性。在 420 例仅有固定标本的可能病例中，58%（244/420）的病例通过 IHC 和/或 PCR 阳性。其中，96%（235/420）的病例通过 IHC 阳性，84%（204/420）的病例通过基于 PCR 的方法阳性。所有方法用于新鲜和福尔马林固定组织标本的寄生虫检测总阳性率相似（分别为 56%和 58%）。虽然基于 PCR 的方法在新鲜样本中更有利于利什曼病的诊断和物种鉴定，但 IHC 与 PCR 联合应用可提高固定样本中利什曼原虫属检测的准确性。总之，PCR 是检测新鲜组织样本中利什曼感染最有效的方法，而对于福尔马林固定样本，应联合使用 IHC 和基于 PCR 的方法。
