8 research outputs found
Molecular detection of rabies lyssaviruses from dogs in Southeastern Nigeria : evidence of transboundary transmission of rabies in West Africa
Despite being the first country to register confirmed cases of Mokola and Lagos bat
lyssaviruses (two very distant lyssaviruses), knowledge gaps, particularly on the molecular
epidemiology of lyssaviruses, still exist in Nigeria. A total of 278 specimens were collected from
dogs in southeastern Nigeria between October 2015 and July 2016, and 23 (8.3%) of these tested
positive for lyssaviruses with the direct fluorescent antibody test (DFA). The lyssaviruses were
genetically characterized by amplifying the highly conserved nucleoprotein (N) gene of the rabies
lyssaviruses (RABVs) of the viral genome. Phylogenetic analyses of the nucleotide sequences showed
that all the RABV sequences in this study were of the Africa-2 lineage. Our results demonstrated
that transboundary transmission of rabies lyssavirus is a key event, given that one of the RABV
sequences (MN196576) clustered with rabies variants from neighboring Niger Republic. Furthermore,
three RABVs from dogs from Anambra State clustered separately forming a novel and distinct
group. Our results demonstrated that transboundary transmission of RABLVs is a key driver in
the spread of rabies in West Africa. In order for the successful control of this zoonotic disease,
a multinational stepwise surveillance and elimination of rabies in Africa by 2030 is probably the
solution for regional elimination.The Tertiary Educational Trust Fund (TETFund) of the Nigerian government through University of Nigeria IBR and Bench Space Intervention (TETFUND/DESS/UNI/NSUKKA/RP/VOL.V) and also the ARC-OVI National Assets [P10000029] Onderstepoort Veterinary Institute, South Africa.http://www.mdpi.com/journal/virusesam2021Veterinary Tropical Disease
Detection of lyssavirus antigen and antibody levels among apparently healthy and suspected rabid dogs in South‑Eastern Nigeria
OBJECTIVES : Domestic dogs are the main reservoir of rabies virus (RABV) infection in Nigeria, thus surveillance of
rabies in dog populations is crucial in order to understand the patterns of spread of infection and ultimately devise
an appropriate rabies control strategy. This study determined the presence of lyssavirus antigen in brain tissues and
anti-rabies antibodies in sera of apparently healthy and suspected-rabid dogs slaughtered for human consumption at
local markets in South-Eastern Nigeria.
RESULTS : Our findings demonstrated that 8.3% (n = 23) of brain tissues were lyssavirus positive and 2.5% (n = 25) of
sera had rabies antibody levels as percentage blocking of 70% and above correlating with a cut-off value ≥ 0.5 IU/
mL in the fluorescent antibody neutralization test. There was an inverse correlation between lyssavirus positivity and
rabies antibody levels confirming that infected individuals most often do not develop virus neutralizing antibodies to
the disease. The low percentage of rabies antibodies in this dog population suggests a susceptible population at high
risk to RABV infection. These findings highlight a huge challenge to national rabies programs and subsequent elimination
of the disease from Nigeria, considering that majority of dogs are confined to rural communal areas, where
parenteral dog vaccination is not routinely undertaken.Additional file 1. Geographical location of South Eastern Nigeria and the
States involved in the study. Map of the study area.The authors thank staff of National Veterinary Research Institute, Vom Plateau
State, Nigeria and OIE Rabies Reference Laboratory, Onderstepoort, South
Africa for laboratory and technical support. We also thank Dr. Ekene Ezenduka
for assistance with the data analysis.This work was partly funded by the Tertiary Educational Trust Fund (TETFund)
of the Nigerian government through University of Nigeria IBR Intervention
(TETFUND/DESS/UNI/NSUKKA/RP/VOL.V) and the ARC-OVI National
Assets [P10000029]. The bench work was undertaken at the Rabies Unit,
Onderstepoort Veterinary Institute, South Africa. The TETFund and ARC-OVI
National Assets were involved in the design of the study, TETFund funded the
collection of data and analyses in Nigeria, while the ARC-OVI was responsible
for the analyses of data in South Africa and manuscript writing.https://bmcresnotes.biomedcentral.comam2019Veterinary Tropical Disease
Economic and feasibility comparison of the dRIT and DFA for decentralized rabies diagnosis in resource-limited settings : the use of Nigerian dog meat markets as a case study
BACKGROUND : Rabies lyssavirus (RABV) is the aetiologic agent of rabies, a disease that is severely underreported in Nigeria as well as elsewhere in Africa and Asia. Despite the role that rabies diagnosis plays towards elucidating the true burden of the disease, Nigeria–a country of 180 million inhabitants–has a limited number of diagnostic facilities. In this study, we sought to investigate two of the World Organization for Animal Health (OIE)-recommended diagnostic assays for rabies–viz; the direct fluorescent antibody test (DFA) and the direct rapid immunohistochemical test (dRIT) in terms of their relative suitability in resource-limited settings. Our primary considerations were (1) the financial feasibility for implementation and (2) the diagnostic efficacy. As a case study, we used suspect rabies samples from dog meat markets in Nigeria. METHODS/PRINCIPAL FINDINGS : By developing a simple simulation framework, we suggested that the assay with the lowest cost to implement and routinely use was the dRIT assay. The costs associated with the dRIT were lower in all simulated scenarios, irrespective of the number of samples tested per year. In addition to the cost analysis, the diagnostic efficacies of the two assays were evaluated. To do this, a cohort of DFA-positive and -negative samples collected from dog meat markets in Nigeria were initially diagnosed using the DFA in Nigeria and subsequently sent to South Africa for diagnostic confirmation. In South Africa, all the specimens were re-tested with the DFA, the dRIT and a quantitative real-time polymerase chain reaction (qRT-PCR). In our investigation, discrepancies were observed between the three diagnostic assays; with the incongruent results being resolved by means of confirmatory testing using the heminested reverse transcription polymerase reaction and sequencing to confirm that they were not contamination. CONCLUSIONS/SIGNIFICANCE : The data obtained from this study suggested that the dRIT was not only an effective diagnostic assay that could be used to routinely diagnose rabies, but that the assay was also the most cost-effective option among all of the OIE recommended methods. In addition, the results of our investigation confirmed that some of the dogs slaughtered in dog markets were rabies-positive and that the markets posed a potential public health threat. Lastly, our data showed that the DFA, although regarded as the gold standard test for rabies, has some limitations—particularly at low antigen levels. Based on the results reported here and the current challenges faced in Nigeria, we believe that the dRIT assay would be the most suitable laboratory test for decentralized or confirmatory rabies diagnosis in Nigeria, given its relative speed, accuracy, cost and ease of use.S1 File. Estimating the potential cost of implementing rabies diagnostic assays in developing
countries.S2 File. Neuronal tissue sample cohort from Nigeria depicting the estimated viral RNA
copy numbers as determined using a quantitative real-time polymerase chain reaction
assay.The Tertiary Educational Trust Fund (TETFund) of the Nigerian government through University of Nigeria Bench Space Intervention, the ARC-OVI National Assets, the TETFund and ARC-OVI fund.https://journals.plos.org/plosntdsam2021BiochemistryGeneticsMicrobiology and Plant PathologyVeterinary Tropical Disease
Economic and feasibility comparison of the dRIT and DFA for decentralized rabies diagnosis in resource-limited settings: The use of Nigerian dog meat markets as a case study.
BACKGROUND:Rabies lyssavirus (RABV) is the aetiologic agent of rabies, a disease that is severely underreported in Nigeria as well as elsewhere in Africa and Asia. Despite the role that rabies diagnosis plays towards elucidating the true burden of the disease, Nigeria-a country of 180 million inhabitants-has a limited number of diagnostic facilities. In this study, we sought to investigate two of the World Organization for Animal Health (OIE)-recommended diagnostic assays for rabies-viz; the direct fluorescent antibody test (DFA) and the direct rapid immunohistochemical test (dRIT) in terms of their relative suitability in resource-limited settings. Our primary considerations were (1) the financial feasibility for implementation and (2) the diagnostic efficacy. As a case study, we used suspect rabies samples from dog meat markets in Nigeria. METHODS/PRINCIPAL FINDINGS:By developing a simple simulation framework, we suggested that the assay with the lowest cost to implement and routinely use was the dRIT assay. The costs associated with the dRIT were lower in all simulated scenarios, irrespective of the number of samples tested per year. In addition to the cost analysis, the diagnostic efficacies of the two assays were evaluated. To do this, a cohort of DFA-positive and -negative samples collected from dog meat markets in Nigeria were initially diagnosed using the DFA in Nigeria and subsequently sent to South Africa for diagnostic confirmation. In South Africa, all the specimens were re-tested with the DFA, the dRIT and a quantitative real-time polymerase chain reaction (qRT-PCR). In our investigation, discrepancies were observed between the three diagnostic assays; with the incongruent results being resolved by means of confirmatory testing using the heminested reverse transcription polymerase reaction and sequencing to confirm that they were not contamination. CONCLUSIONS/SIGNIFICANCE:The data obtained from this study suggested that the dRIT was not only an effective diagnostic assay that could be used to routinely diagnose rabies, but that the assay was also the most cost-effective option among all of the OIE recommended methods. In addition, the results of our investigation confirmed that some of the dogs slaughtered in dog markets were rabies-positive and that the markets posed a potential public health threat. Lastly, our data showed that the DFA, although regarded as the gold standard test for rabies, has some limitations-particularly at low antigen levels. Based on the results reported here and the current challenges faced in Nigeria, we believe that the dRIT assay would be the most suitable laboratory test for decentralized or confirmatory rabies diagnosis in Nigeria, given its relative speed, accuracy, cost and ease of use
Detection of lyssavirus antigen and antibody levels among apparently healthy and suspected rabid dogs in South-Eastern Nigeria
Additional file 1. Geographical location of South Eastern Nigeria and the States involved in the study. Map of the study area