Practical and effective diagnosis of animal anthrax in endemic low-resource settings

Aminu, O. R. et al. (2020) Practical and effective diagnosis of animal anthrax in endemic low-resource settings. PLoS Neglected Tropical Diseases, 14(9), e0008655. (doi: 10.1371/journal.pntd.0008655) (PMID:32925904) (PMCID:PMC7513992)

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Abstract

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.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Aminu, Ms Rhoda and Lembo, Dr Tiziana and Biek, Professor Roman and Denwood, Dr Matthew and Zadoks, Professor Ruth and Forde, Dr Taya
Creator Roles:
Aminu, O. R.Conceptualization, Formal analysis, Investigation, Methodology, Writing – original draft, Writing – review and editing
Lembo, T.Conceptualization, Funding acquisition, Methodology, Project administration, Supervision, Writing – review and editing
Zadoks, R. N.Conceptualization, Methodology, Supervision, Writing – review and editing
Biek, R.Conceptualization, Methodology, Supervision, Writing – review and editing
Denwood, M.Formal analysis, Methodology, Writing – review and editing
Forde, T. L.Conceptualization, Investigation, Methodology, Supervision, Writing – review and editing
Authors: Aminu, O. R., Lembo, T., Zadoks, R. N., Biek, R., Lewis, S., Kiwelu, I., Mmbaga, B. T., Mshanga, D., Shirima, G., Denwood, M., and Forde, T. L.
College/School:College of Medical Veterinary and Life Sciences > Institute of Biodiversity Animal Health and Comparative Medicine
College of Medical Veterinary and Life Sciences > School of Medicine, Dentistry & Nursing
College of Medical Veterinary and Life Sciences > School of Veterinary Medicine
Journal Name:PLoS Neglected Tropical Diseases
Publisher:Public Library of Science
ISSN:1935-2727
ISSN (Online):1935-2735
Published Online:14 September 2020
Copyright Holders:Copyright © 2020 Aminu et al.
First Published:First published in PLoS Neglected Tropical Diseases 14(9): e0008655
Publisher Policy:Reproduced under a Creative Commons License
Data DOI:10.5525/gla.researchdata.1057

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
171848Molecular epidemiology of Bacillus anthracis: novel data and techniques for local surveillance in TanzaniaRoman BiekEuropean Commission (EC)659223Institute of Biodiversity, Animal Health and Comparative Medicine
300423Novel molecular approaches for understanding the epidemiology of endemic anthraxTaya FordeBiotechnology and Biological Sciences Research Council (BBSRC)BB/R012075/1Institute of Biodiversity, Animal Health and Comparative Medicine