Introduction into Nigeria of a Distinct Genotype of Avian Influenza Virus (H5N1)

Genetic characterization of highly pathogenic avian influenza viruses (H5N1) isolated in July 2008 in Nigeria indicates that a distinct genotype, never before detected in Africa, reached the continent. Phylogenetic analysis showed that the viruses are genetically closely related to European and Middle Eastern influenza A (H5N1) isolates detected in 2007

Reassortant Avian Influenza Virus (H5N1) in Poultry, Nigeria, 2007

Reassortant Influenza Virus (H5N1) in Poultry, Nigeria, 200

Genome Analysis Linking Recent European and African Influenza (H5N1) Viruses

Although linked, these viruses are distinct from earlier outbreak strains

Highly Pathogenic Avian Influenza Virus Subtype H5N1 in Africa: A Comprehensive Phylogenetic Analysis and Molecular Characterization of Isolates

Highly pathogenic avian influenza virus A/H5N1 was first officially reported in Africa in early 2006. Since the first outbreak in Nigeria, this virus spread rapidly to other African countries. From its emergence to early 2008, 11 African countries experienced A/H5N1 outbreaks in poultry and human cases were also reported in three of these countries. At present, little is known of the epidemiology and molecular evolution of A/H5N1 viruses in Africa. We have generated 494 full gene sequences from 67 African isolates and applied molecular analysis tools to a total of 1,152 A/H5N1 sequences obtained from viruses isolated in Africa, Europe and the Middle East between 2006 and early 2008. Detailed phylogenetic analyses of the 8 gene viral segments confirmed that 3 distinct sublineages were introduced, which have persisted and spread across the continent over this 2-year period. Additionally, our molecular epidemiological studies highlighted the association between genetic clustering and area of origin in a majority of cases. Molecular signatures unique to strains isolated in selected areas also gave us a clearer picture of the spread of A/H5N1 viruses across the continent. Mutations described as typical of human influenza viruses in the genes coding for internal proteins or associated with host adaptation and increased resistance to antiviral drugs have also been detected in the genes coding for transmembrane proteins. These findings raise concern for the possible human health risk presented by viruses with these genetic properties and highlight the need for increased efforts to monitor the evolution of A/H5N1 viruses across the African continent. They further stress how imperative it is to implement sustainable control strategies to improve animal and public health at a global level

Evidence of Infection by H5N2 Highly Pathogenic Avian Influenza Viruses in Healthy Wild Waterfowl

The potential existence of a wild bird reservoir for highly pathogenic avian influenza (HPAI) has been recently questioned by the spread and the persisting circulation of H5N1 HPAI viruses, responsible for concurrent outbreaks in migratory and domestic birds over Asia, Europe, and Africa. During a large-scale surveillance programme over Eastern Europe, the Middle East, and Africa, we detected avian influenza viruses of H5N2 subtype with a highly pathogenic (HP) viral genotype in healthy birds of two wild waterfowl species sampled in Nigeria. We monitored the survival and regional movements of one of the infected birds through satellite telemetry, providing a rare evidence of a non-lethal natural infection by an HP viral genotype in wild birds. Phylogenetic analysis of the H5N2 viruses revealed close genetic relationships with H5 viruses of low pathogenicity circulating in Eurasian wild and domestic ducks. In addition, genetic analysis did not reveal known gallinaceous poultry adaptive mutations, suggesting that the emergence of HP strains could have taken place in either wild or domestic ducks or in non-gallinaceous species. The presence of coexisting but genetically distinguishable avian influenza viruses with an HP viral genotype in two cohabiting species of wild waterfowl, with evidence of non-lethal infection at least in one species and without evidence of prior extensive circulation of the virus in domestic poultry, suggest that some strains with a potential high pathogenicity for poultry could be maintained in a community of wild waterfowl

Disentangling the role of Africa in the global spread of H5 highly pathogenic avian influenza

The role of Africa in the dynamics of the global spread of a zoonotic and economicallyimportant 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.USAID under the OSRO/GLO/501/USA and OSRO/GLO/507/USA projects and by European Union’s Horizon 2020 research and innovation programme under grant agreement No 727922 (DELTAFLU). The European Research Council under the European Unionʼs Horizon 2020 research and innovation programme (grant agreement no. 725422-ReservoirDOCS). P.L. acknowledges support by the Research Foundation – Flanders FWO, G066215N, G0D5117N and G0B9317N). B.V. is a postdoctoral research fellow supported by the FWO.http://www.nature.com/naturecommunicationsam2020Microbiology and Plant Patholog

Molecular characterization and epidemiology of the highly pathogenic avian influenza H5N1 in Nigeria

Avian influenza caused infection and spread throughout Nigeria in 2006. Carcass samples (lung,liver, spleen, heart, trachea and intestine) from the different regions of Nigeria were processed for virus isolation. Infective allantoic fluids were tested for avian influenza viruses (AIV) and Newcastle disease virus using monospecific antisera. Thirty-five isolates were generated and characterized molecularly using the haemagglutinin gene. The molecular analysis indicated that different sublineages of the highly pathogenic avian influenza (HPAI) H5N1 viruses spread throughout Nigeria. We compared the Nigerian isolates with others from Africa and results indicated close similarities between isolates from West Africa and Sudan. Some of the analysed viruses showed genetic drift, and the implications of these for future epidemiology and ecology of avian influenza in Africa require further evaluation. The spread of primary outbreaks was strongly linked to trade (legal and illegal), live bird markets, inappropriate disposal, and poorly implemented control measures. No strong correlation existed between wild birds and HPAI H5N1 in Nigeria.ARC–Onderstepoort Veterinary Institute, South Africa; The Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria; The Helena Jooste Bursary and National Veterinary Research Institute, Nigeria

Community measures : a key to highly pathogenic avian influenza control in developing nations

Avian influenza, a transboundary poultry disease of great economic importance, has been ravaging the poultry industry worldwide since the 1950s. The virus usually occurs as waves of epizootics in the poultry industry causing fatality and disruption in trade both locally and internationally. That the virus has the ability to mutate in the avian host has limited effort to control the pathogen. The current wave of outbreaks starting in mid to late 2003 has led to the death of hundreds of millions of poultry flock worldwide in addition to death of other bird and animal species. The rapidity and mode of spread of the virus is daunting, and epizootiologists as well as authorities are still at a crossroad on the best combination of effective control measures. Surveillance, biosecurity, stamping out, and vaccination are the best available and generally acceptable methods of controlling the disease. While several countries are still undecided whether to adopt vaccination as a control strategy, the highly pathogenic notifiable form of avian influenza continues to ravage the poultry industry. In countries with outbreaks, the virus spreads so fast that almost whole chicken populations in affected regions are wiped out. This study review the outbreaks in Nigeria, sero-surveillance studies and diagnostics carried out during the outbreaks, and strategies adopted by a community at high risk in the wave of outbreaks in Nigeria to prevent it from being infected. These data are presented as a good measure for developing economies in view of similarities in the poultry sectors