ABSTRACT
Avian influenza viruses (AIV) are negative sense RNA viruses posing a major threat to the poultry industry worldwide, with the potential to spread to mammals, including humans; hence, an accurate and rapid AIV diagnosis is essential. To date AIV detection relies on molecular methods, mainly RT-qPCR directed against AIV M gene segment. The evolution of AIV represents a relevant issue in diagnostic RT-qPCR due to possible mispriming and/or probe-binding failures resulting in false negative results. Consequently, RT-qPCR for AIV detection should be periodically re-assessed both in silico and in vitro. To this end, a specific workflow was developed to evaluate in silico the complementarity of primers and probes of four published RT-qPCR protocols to their target regions. The four assays and one commercially available kit for AIV detection were evaluated both for their analytical sensitivity using eight different viral dilution panels and for their diagnostic performances against clinical specimens of known infectious status. Differences were observed among the tests under evaluation, both in terms of analytical sensitivity and of diagnostic performances. This finding confirms the importance of continuously monitoring the primers and probes complementarity to their binding regions.
Subject(s)
Computer Simulation , Genetic Variation , Influenza A virus/classification , Influenza A virus/genetics , Influenza in Birds/diagnosis , RNA, Viral/analysis , Real-Time Polymerase Chain Reaction/methods , Viral Proteins/genetics , Animals , Birds , In Vitro Techniques , Influenza A virus/isolation & purification , Influenza in Birds/genetics , Influenza in Birds/virology , RNA, Viral/genetics , ROC CurveABSTRACT
Influenza D virus (IDV) has been identified in several continents, with serological evidence for the virus in Africa. In order to improve the sensitivity and cost-benefit of IDV surveillance in Togo, risk maps were drawn using a spatial multicriteria decision analysis (MCDA) and experts' opinion to evaluate the relevance of sampling areas used so far. Areas at highest risk of IDV occurrence were the main cattle markets. The maps were evaluated with previous field surveillance data collected in Togo between 2017 and 2019: 1216 sera from cattle, small ruminants, and swine were screened for antibodies to IDV by hemagglutination inhibition (HI) assays. While further samples collections are needed to validate the maps, the risk maps resulting from the spatial MCDA approach generated here highlight several priority areas for IDV circulation assessment.
Subject(s)
Decision Support Techniques , Epidemiological Monitoring/veterinary , Orthomyxoviridae Infections/veterinary , Thogotovirus , Animals , Antibodies, Viral/blood , Cattle , Hemagglutination Inhibition Tests , Orthomyxoviridae Infections/epidemiology , Risk Factors , Ruminants/virology , Spatial Analysis , Swine/virology , Togo/epidemiologyABSTRACT
In 2015, highly pathogenic avian influenza A(H5N1) viruses reemerged in poultry in West Africa. We describe the introduction of a reassortant clade 2.3.2.1c virus into Togo in April 2018. Our findings signal further local spread and evolution of these viruses, which could affect animal and human health.
Subject(s)
Biological Evolution , Influenza A Virus, H5N1 Subtype/classification , Influenza A Virus, H5N1 Subtype/genetics , Influenza in Birds/epidemiology , Influenza in Birds/virology , Poultry/virology , Animals , Hemagglutinin Glycoproteins, Influenza Virus/genetics , History, 21st Century , Influenza in Birds/history , Neuraminidase/genetics , Public Health Surveillance , Togo/epidemiology , Viral Proteins/geneticsABSTRACT
The role of Africa in the dynamics of the global spread of a zoonotic and economically-important virus, such as the highly pathogenic avian influenza (HPAI) H5Nx of the Gs/GD lineage, remains unexplored. Here we characterise the spatiotemporal patterns of virus diffusion during three HPAI H5Nx intercontinental epidemic waves and demonstrate that Africa mainly acted as an ecological sink of the HPAI H5Nx viruses. A joint analysis of host dynamics and continuous spatial diffusion indicates that poultry trade as well as wild bird migrations have contributed to the virus spreading into Africa, with West Africa acting as a crucial hotspot for virus introduction and dissemination into the continent. We demonstrate varying paths of avian influenza incursions into Africa as well as virus spread within Africa over time, which reveal that virus expansion is a complex phenomenon, shaped by an intricate interplay between avian host ecology, virus characteristics and environmental variables.