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Claassen DD, Odendaal L, Sabeta CT, Fosgate GT, Mohale DK, Williams JH, Clift SJ. Diagnostic sensitivity and specificity of immunohistochemistry for the detection of rabies virus in domestic and wild animals in South Africa. J Vet Diagn Invest 2023; 35:236-245. [PMID: 36782370 PMCID: PMC10185990 DOI: 10.1177/10406387231154537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023] Open
Abstract
We estimated the diagnostic sensitivity (DSe) and specificity (DSp) of an immunohistochemistry (IHC) protocol compared to the direct fluorescent antibody test (DFAT), which is the gold standard test for rabies diagnosis. We obtained brain samples from 199 domestic and wild animal cases (100 DFAT-negative, 99 DFAT-positive), by convenience sampling from 2 government-accredited rabies virus (RABV) testing laboratories in South Africa, between February 2015 and August 2017. Tissues that had been stored at 4-8°C for several days to weeks at the 2 accredited laboratories were formalin-fixed and paraffin-embedded. Nighty-eight cases tested IHC-positive using a polyclonal anti-RABV nucleoprotein antibody and a polymer detection system. The overall DSe and DSp for the RABV IHC test were 98% (95% CI: 93-100%) and 99% (95% CI: 95-100%), respectively. Domestic dogs accounted for 41 of 98 RABV IHC-positive cases, with the remainder in 4 domestic cats, 25 livestock, and 28 wildlife. Herpestidae species, including 7 meerkats and 9 other mongoose species, were the most frequently infected wild carnivores, followed by 11 jackals. Three cases in domestic dogs had discordant test results; 2 cases were IHC-/DFAT+ and 1 case was IHC+/DFAT-. Considering the implications of a false-negative rabies diagnosis, participating in regular inter-laboratory comparisons is vital, and a secondary or confirmatory method, such as IHC, should be performed on all submitted specimens, particularly negative cases with human contact history.
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Affiliation(s)
- Drienie D. Claassen
- Departments of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Pretoria, Gauteng, South Africa
| | - Lieza Odendaal
- Departments of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Pretoria, Gauteng, South Africa
| | - Claude T. Sabeta
- Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Pretoria, Gauteng, South Africa
| | - Geoffrey T. Fosgate
- Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, Pretoria, Gauteng, South Africa
| | - Debrah K. Mohale
- Agricultural Research Council–Onderstepoort Veterinary Research, Onderstepoort, Gauteng, South Africa
| | - June H. Williams
- Departments of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Pretoria, Gauteng, South Africa
| | - Sarah J. Clift
- Departments of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Pretoria, Gauteng, South Africa
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Condori RE, Niezgoda M, Lopez G, Matos CA, Mateo ED, Gigante C, Hartloge C, Filpo AP, Haim J, Satheshkumar PS, Petersen B, Wallace R, Olson V, Li Y. Using the LN34 Pan-Lyssavirus Real-Time RT-PCR Assay for Rabies Diagnosis and Rapid Genetic Typing from Formalin-Fixed Human Brain Tissue. Viruses 2020; 12:v12010120. [PMID: 31963651 PMCID: PMC7019996 DOI: 10.3390/v12010120] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 01/10/2020] [Accepted: 01/15/2020] [Indexed: 11/16/2022] Open
Abstract
Human rabies post mortem diagnostic samples are often preserved in formalin. While immunohistochemistry (IHC) has been routinely used for rabies antigen detection in formalin-fixed tissue, the formalin fixation process causes nucleic acid fragmentation that may affect PCR amplification. This study reports the diagnosis of rabies in an individual from the Dominican Republic using both IHC and the LN34 pan-lyssavirus real-time RT-PCR assay on formalin-fixed brain tissue. The LN34 assay generates a 165 bp amplicon and demonstrated higher sensitivity than traditional PCR. Multiple efforts to amplify nucleic acid fragments larger than 300 bp using conventional PCR were unsuccessful, probably due to RNA fragmentation. Sequences generated from the LN34 amplicon linked the case to the rabies virus (RABV) strain circulating in the Ouest Department of Haiti to the border region between Haiti and the Dominican Republic. Direct sequencing of the LN34 amplicon allowed rapid and low-cost rabies genetic typing.
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Affiliation(s)
- Rene Edgar Condori
- Pox and Rabies Branch, Centers for Disease Control and Prevention, Atlanta, GA 30329, USA
| | - Michael Niezgoda
- Pox and Rabies Branch, Centers for Disease Control and Prevention, Atlanta, GA 30329, USA
| | - Griselda Lopez
- Laboratorio de Salud Pública “Dr. Defillo”, 10105 Santo Domingo, Dominican Republic
| | | | - Elinna Diaz Mateo
- Centro de Prevención y Control de Enfermedades Transmitidas por Vectores y Zoonosis (CECOVEZ), 10308 Santo Domingo, Dominican Republic
| | - Crystal Gigante
- Pox and Rabies Branch, Centers for Disease Control and Prevention, Atlanta, GA 30329, USA
- Oak Ridge Institute for Science and Education, Oak Ridge, TN 37830, USA
| | - Claire Hartloge
- Pox and Rabies Branch, Centers for Disease Control and Prevention, Atlanta, GA 30329, USA
- Oak Ridge Institute for Science and Education, Oak Ridge, TN 37830, USA
| | | | - Joseph Haim
- Ministère de l’Agriculture, des Resources Naturelles et du Développement Rural, Department of Animal Health, HT 6110, Republic of Haiti
| | | | - Brett Petersen
- Pox and Rabies Branch, Centers for Disease Control and Prevention, Atlanta, GA 30329, USA
| | - Ryan Wallace
- Pox and Rabies Branch, Centers for Disease Control and Prevention, Atlanta, GA 30329, USA
| | - Victoria Olson
- Pox and Rabies Branch, Centers for Disease Control and Prevention, Atlanta, GA 30329, USA
| | - Yu Li
- Pox and Rabies Branch, Centers for Disease Control and Prevention, Atlanta, GA 30329, USA
- Correspondence:
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Beck S, Gunawardena P, Horton DL, Hicks DJ, Marston DA, Ortiz-Pelaez A, Fooks AR, Núñez A. Pathobiological investigation of naturally infected canine rabies cases from Sri Lanka. BMC Vet Res 2017; 13:99. [PMID: 28403882 PMCID: PMC5389160 DOI: 10.1186/s12917-017-1024-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Accepted: 04/03/2017] [Indexed: 12/25/2022] Open
Abstract
Background The recommended screening of rabies in ‘suspect’ animal cases involves testing fresh brain tissue. The preservation of fresh tissue however can be difficult under field conditions and formalin fixation provides a simple alternative that may allow a confirmatory diagnosis. The occurrence and location of histopathological changes and immunohistochemical (IHC) labelling for rabies in formalin fixed paraffin embedded (FFPE) canine brain is described in samples from 57 rabies suspect cases from Sri-Lanka. The presence of Negri bodies and immunohistochemical detection of rabies virus antigen were evaluated in the cortex, hippocampus, cerebellum and brainstem. The effect of autolysis and artefactual degeneration of the tissue was also assessed. Results Rabies was confirmed in 53 of 57 (93%) cases by IHC. IHC labelling was statistically more abundant in the brainstem. Negri bodies were observed in 32 of 53 (60.4%) of the positive cases. Although tissue degradation had no effect on IHC diagnosis, it was associated with an inability to detect Negri bodies. In 13 cases, a confirmatory Polymerase chain reaction (PCR) testing for rabies virus RNA was undertaken by extracting RNA from fresh frozen tissue, and also attempted using FFPE samples. PCR detection using fresh frozen samples was in agreement with the IHC results. The PCR method from FFPE tissues was suitable for control material but unsuccessful in our field cases. Conclusions Histopathological examination of the brain is essential to define the differential diagnoses of behaviour modifying conditions in rabies virus negative cases, but it is unreliable as the sole method for rabies diagnosis, particularly where artefactual change has occurred. Formalin fixation and paraffin embedding does not prevent detection of rabies virus via IHC labelling even where artefactual degeneration has occurred. This could represent a pragmatic secondary assay for rabies diagnosis in the field because formalin fixation can prevent sample degeneration. The brain stem was shown to be the site with most viral immunoreactivity; supporting recommended sampling protocols in favour of improved necropsy safety in the field. PCR testing of formalin fixed tissue may be successful in certain circumstances as an alternative test.
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Affiliation(s)
- S Beck
- Pathology Department, Animal and Plant Health Agency, Weybridge, UK.
| | - P Gunawardena
- Department of Veterinary Pathobiology, University of Peradeniya, Peradeniya, Sri Lanka
| | - D L Horton
- Wildlife Zoonoses and Vector Borne Diseases Research Group, Animal and Plant Health Agency, Weybridge, UK
| | - D J Hicks
- Pathology Department, Animal and Plant Health Agency, Weybridge, UK
| | - D A Marston
- Wildlife Zoonoses and Vector Borne Diseases Research Group, Animal and Plant Health Agency, Weybridge, UK
| | | | - A R Fooks
- Wildlife Zoonoses and Vector Borne Diseases Research Group, Animal and Plant Health Agency, Weybridge, UK
| | - A Núñez
- Pathology Department, Animal and Plant Health Agency, Weybridge, UK
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Markotter W, Coertse J, le Roux K, Peens J, Weyer J, Blumberg L, Nel LH. Utility of forensic detection of rabies virus in decomposed exhumed dog carcasses. J S Afr Vet Assoc 2015; 86:1220. [PMID: 26016574 PMCID: PMC6138121 DOI: 10.4102/jsava.v86i1.1220] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Revised: 12/08/2014] [Accepted: 12/18/2014] [Indexed: 11/18/2022] Open
Abstract
This report describes four suspected rabies cases in domestic dogs that were involved in human exposures. In all these cases, the animals were buried for substantial times before rabies testing was performed. Animal rabies is endemic in South Africa and domestic dogs are the main vector for transmission to humans. Diagnosis of rabies in humans is complicated, and diagnosis in the animal vector can provide circumstantial evidence to support clinical diagnosis of rabies in humans. The gold standard diagnostic method, fluorescent antibody test (FAT), only delivers reliable results when performed on fresh brain material and therefore decomposed samples are rarely submitted for diagnostic testing. Severely decomposed brain material was tested for the presence of rabies virus genomic material using a quantitative real-time reverse transcription polymerase chain reaction (q-real-time RT-PCR) assay when conventional molecular methods were unsuccessful. This may be a useful tool in the investigation of cases where the opportunity to sample the suspected animals post mortem was forfeited and which would not be possible with conventional testing methodologies because of the decomposition of the material.
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Affiliation(s)
- Wanda Markotter
- Department of Microbiology and Plant Pathology, University of Pretoria.
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Sabeta CT, Weyer J, Geertsma P, Mohale D, Miyen J, Blumberg LH, Leman PA, Phahladira B, Shumba W, Walters J, Paweska JT. Emergence of rabies in the Gauteng Province, South Africa: 2010-2011. J S Afr Vet Assoc 2013; 84:E1-5. [PMID: 23718320 DOI: 10.4102/jsava.v84i1.923] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Revised: 02/04/2013] [Accepted: 03/18/2013] [Indexed: 11/01/2022] Open
Abstract
Canine rabies is enzootic throughout Sub-Saharan Africa, including the Republic of South Africa. Historically, in South Africa the coastal provinces of KwaZulu-Natal and Eastern Cape were most affected. Alarmingly, outbreaks of canine rabies have been increasingly reported in the past decade from sites where it has previously been under control. From January 2010 to December 2011, 53 animal rabies cases were confirmed; these were mostly in domestic dogs from southern Johannesburg, which was previously considered to be rabies free. In addition, one case was confirmed in a 26-month old girl who had been scratched by a pet puppy during this period. The introduction of rabies into Gauteng Province was investigated through genetic analysis of rabies positive samples confirmed during the outbreak period. In addition, the nucleotide sequences of incidental cases reported in the province for the past ten years were also included in the analysis. It was found that the recent canine rabies outbreak in the Gauteng Province came from the introduction of the rabies virus from KwaZulu-Natal, with subsequent local spread in the susceptible domestic dog population of southern Johannesburg. The vulnerability of the province was also highlighted through multiple, dead-end introductions in the past ten years. This is the first report of a rabies outbreak in the greater Johannesburg area with evidence of local transmission in the domestic dog population.
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Affiliation(s)
- Claude T Sabeta
- OIE Rabies Reference Laboratory, Agricultural Research Council-Onderstepoort Veterinary Institute ARC-OVI, Onderstepoort, South Africa.
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