Practical and effective diagnosis of animal anthrax in endemic low-resource settings.
Practical and effective diagnosis of animal anthrax in endemic low-resource settings.
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DOI：
10.1371/journal.pntd.0008655
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发表时间：
2020-09
影响因子：
3.8
通讯作者：
Forde TL
中科院分区：
文献类型：
--
作者：
Aminu OR;Lembo T;Zadoks RN;Biek R;Lewis S;Kiwelu I;Mmbaga BT;Mshanga D;Shirima G;Denwood M;Forde TL
炭疽威胁着人类和动物的健康，以及非洲和亚洲许多农村社区人民的生计。在这些地区，炭疽监测因缺乏现场检测工具而受到挑战。此外，文化习俗和基础设施可能会影响样本的可用性和质量。非常需要实用而准确的诊断解决方案来量化炭疽的影响。我们验证了在现场采集的血涂片中检测炭疽芽孢杆菌的显微镜和分子方法，并确定了在没有血涂片的情况下适合炭疽确认的替代样品。我们调查了坦桑尼亚北方怀疑由炭疽引起的牲畜死亡率。现场制备的血涂片（n = 152）进行了测试，通过显微镜使用四种染色技术，以及聚合酶链反应（PCR），然后贝叶斯潜在类分析。中位灵敏度（91%，CI 95% [84-96%]）和特异性（99%，CI 95% [96-100%]）与推荐标准多色亚甲蓝（PMB）相当（92%，CI 95% [84-97%]和98%，CI 95% [95-100%]），但天青B更容易获得和方便。其他常用的染色剂表现不佳。由于当地的习俗和条件，50%以下的疑似炭疽病例可以获得血涂片。然而，几乎总是可用的皮肤DNA提取物的PCR具有高灵敏度和特异性（分别为95%，CI 95% [90-98%]和95%，CI 95% [87-99%]），即使在环境温度下长期储存后也是如此。Azure B显微镜是一种精确的动物炭疽诊断测试，可以在基本的实验室基础设施和现场进行。当血液涂片不可用时，使用皮肤组织的PCR提供了一种有价值的替代确认方法。我们的研究结果为低资源环境中的炭疽病提供了一种实用的诊断方法，可以支持全球炭疽病流行国家的监测和控制工作。炭疽病是一种古老的疾病，在发达国家得到了很大程度的控制，但在中低收入国家的偏远和农村社区仍然很普遍，影响着人类和动物的健康和生计。为了有效地控制炭疽，检测和准确确认是重要的，但解决方案需要在资源和基础设施通常有限的受影响最严重的地区可行。为了实现这一目标，我们评估了一种新提出的染色剂，天青B，用于动物血涂片的显微镜确认，因为这种方法可以在低资源实验室和现场实施。与其他推荐的染色剂相比，使用天青B的显微镜检查具有高度准确性，并且具有更容易获得和方便的额外优势。然而，一半以上的疑似病例没有血液涂片样本。因此，我们评估了其他样品类型的全血，血拭子，皮肤和苍蝇在环境温度下储存的分子检测（PCR）。我们表现出高性能的PCR与皮肤组织，可用于90%的尸体。因此，在实地条件下，涂片样本（如有）和组织样本最适合用于动物炭疽病的诊断测试，可在受影响地区进行显微镜检查，在国内参考实验室进行聚合酶链反应。
Anthrax threatens human and animal health, and people’s livelihoods in many rural communities in Africa and Asia. In these areas, anthrax surveillance is challenged by a lack of tools for on-site detection. Furthermore, cultural practices and infrastructure may affect sample availability and quality. Practical yet accurate diagnostic solutions are greatly needed to quantify anthrax impacts. We validated microscopic and molecular methods for the detection of Bacillus anthracis in field-collected blood smears and identified alternative samples suitable for anthrax confirmation in the absence of blood smears. We investigated livestock mortalities suspected to be caused by anthrax in northern Tanzania. Field-prepared blood smears (n = 152) were tested by microscopy using four staining techniques as well as polymerase chain reaction (PCR) followed by Bayesian latent class analysis. Median sensitivity (91%, CI 95% [84–96%]) and specificity (99%, CI 95% [96–100%]) of microscopy using azure B were comparable to those of the recommended standard, polychrome methylene blue, PMB (92%, CI 95% [84–97%] and 98%, CI 95% [95–100%], respectively), but azure B is more available and convenient. Other commonly-used stains performed poorly. Blood smears could be obtained for <50% of suspected anthrax cases due to local customs and conditions. However, PCR on DNA extracts from skin, which was almost always available, had high sensitivity and specificity (95%, CI 95% [90–98%] and 95%, CI 95% [87–99%], respectively), even after extended storage at ambient temperature. Azure B microscopy represents an accurate diagnostic test for animal anthrax that can be performed with basic laboratory infrastructure and in the field. When blood smears are unavailable, PCR using skin tissues provides a valuable alternative for confirmation. Our findings lead to a practical diagnostic approach for anthrax in low-resource settings that can support surveillance and control efforts for anthrax-endemic countries globally. Anthrax, an ancient disease largely controlled in the developed world, is still widespread in remote and rural communities of low- and middle-income countries where it affects human and animal health, and livelihoods. To control anthrax effectively, detection and accurate confirmation are important, but solutions need to be feasible for the most-affected areas where resources and infrastructure are typically limited. To achieve this, we assessed a newly proposed stain, azure B, for microscopic confirmation on animal blood smears, as this method can be implemented in low-resource laboratories and in the field. Microscopy using azure B was highly accurate compared to other recommended stains and has the added advantage of being more readily available and convenient. However, blood smear samples were unavailable for more than half of suspected cases. We therefore evaluated a molecular test (PCR) on other sample types–whole blood, blood swabs, skin, and flies–stored at ambient temperature. We show high performance of PCR with skin tissues which were available for 90% of carcasses. Thus, under field conditions, smear samples (when available) and tissue samples are most suitable for diagnostic testing of animal anthrax, whereby microscopy can be conducted in affected areas and PCR in in-country reference laboratories.
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影响因子：
5.8
作者：
Denwood, Matthew J.
通讯作者：
Denwood, Matthew J.
DOI：
10.1016/s0027-5107(97)00314-x
发表时间：
1998-06-05
影响因子：
2.3
作者：
Douglas, MP;Rogers, SO
通讯作者：
Rogers, SO
影响因子：
4.4
作者：
Dragon, DC;Bader, DE;Woollen, N
通讯作者：
Woollen, N
影响因子：
64.8
作者：
Hoffmann, Constanze;Zimmermann, Fee;Leendertz, Fabian H.
通讯作者：
Leendertz, Fabian H.
影响因子：
9.4
作者：
Coker, PR;Smith, KL;Hugh-Jones, ME
通讯作者：
Hugh-Jones, ME