Evidence of Infection by H5N2 Highly Pathogenic Avian Influenza Viruses In Healthy Wild Waterfowl (original) (raw)
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Reassortant low-pathogenic avian influenza H5N2 viruses in African wild birds
The Journal of general virology, 2011
To investigate the presence and persistence of avian influenza virus in African birds, we monitored avian influenza in wild and domestic birds in two different regions in Nigeria. We found low-pathogenic avian influenza (LPAI) H5N2 viruses in three spur-winged geese (Plectropterus gambensis) in the Hadejia-Nguru wetlands. Phylogenetic analyses revealed that all of the genes, except the non-structural (NS) genes, of the LPAI H5N2 viruses were more closely related to genes recently found in wild and domestic birds in Europe. The NS genes formed a sister group to South African and Zambian NS genes. This suggested that the Nigerian LPAI H5N2 viruses found in wild birds were reassortants exhibiting an NS gene that circulated for at least 7 years in African birds and is part of the African influenza gene pool, and genes that were more recently introduced into Africa from Eurasia, most probably by intercontinental migratory birds. Interestingly the haemagglutinin and neuraminidase genes fo...
Infectious Diseases of Poverty, 2014
Background: To monitor carrier hosts of avian influenza in Nigeria, we randomly collected cloaca swab specimens from 155 ducks at a live bird market (LBM) in Ibadan, southwest Nigeria, between July 2011 and July 2012. Methods: The samples were analyzed by real-time reverse transcription-polymerase chain reaction (RT-PCR) and virus isolation was carried out in embryonated chicken eggs. Partial sequencing of the antigenic cleavage site of the haemagglutinin (HA) gene was performed, multiple sequence alignment was carried out using ClustalW, and a phylogenetic tree was constructed using the neighbor joining method. Results: Twenty (13%) of the 155 samples were positive for avian influenza subtype H5N2 by real-time RT-PCR and three isolates were obtained from embryonated chicken eggs. Partial sequencing of the amino acid cleavage site of the HA genes of two isolates corresponded to a PQRETGL*F sequence that is common in low pathogenic avian influenza (LPAI). Phylogenetically, the HA genes of the two influenza viruses are monophyletic and clustered with H5N2 viruses detected in wild ducks from Africa. Conclusion: The occurrence of LPAI in domestic ducks in Nigeria underscores the importance of continuous surveillance and monitoring of the virus (in a country that is considered to be free of avian influenza) in order to prevent the emergence of virulent strains that may spread to commercial poultry and humans.
Advances in Animal and Veterinary Sciences
H PAI viruses is a source of major concern for poultry and human health. The hemagglutinin (HA) genes of subtype H5 evolved through reassortment with various neuraminidase subtypes (1-9) to comprise AI H5NX viruses. The co-circulation of group A viruses with low patho-genic avian influenza (LPAI) viruses resulted in emergence of novel reassortants; H5N1 and H5N8 (El-Shesheny et al., 2017). H5N8 viruses has been emerged in Asia since 2010 where the first outbreaks in breeding ducks occurred in China then South Korea, Japan and Taiwan 2014. then quickly spread to other continents as Europe, North America and Africa (Lee et al., 2014).
Viruses
Numerous outbreaks of high-pathogenicity avian influenza (HPAI) were reported during 2020–2021. In Africa, H5Nx has been detected in Benin, Burkina Faso, Nigeria, Senegal, Lesotho, Namibia and South Africa in both wild birds and poultry. Botswana reported its first outbreak of HPAI to the World Organisation for Animal Health (WOAH) in 2021. An H5N1 virus was detected in a fish eagle, doves, and chickens. Full genome sequence analysis revealed that the virus belonged to clade 2.3.4.4b and showed high identity within haemagglutinin (HA) and neuraminidase proteins (NA) for viruses identified across a geographically broad range of locations. The detection of H5N1 in Botswana has important implications for disease management, wild bird conservation, tourism, public health, economic empowerment of vulnerable communities and food security in the region.
Highly pathogenic avian influenza H5N1 Clade 2.3.2.1c virus in migratory birds, 2014-2015
Virologica Sinica, 2016
A novel Clade 2.3.2.1c H5N1 reassortant virus caused several outbreaks in wild birds in some regions of China from late 2014 to 2015. Based on the genetic and phylogenetic analyses, the viruses possess a stable gene constellation with a Clade 2.3.2.1c HA, a H9N2-derived PB2 gene and the other six genes of Asian H5N1-origin. The Clade 2.3.2.1c H5N1 reassortants displayed a high genetic relationship to a human H5N1 strain (A/Alberta/01/2014). Further analysis showed that similar viruses have been circulating in wild birds in China, Russia, Dubai (Western Asia), Bulgaria and Romania (Europe), as well as domestic poultry in some regions of Africa. The affected areas include the Central Asian, East Asian-Australasian, West Asian-East African, and Black Sea/Mediterranean flyways. These results show that the novel Clade 2.3.2.1c reassortant viruses are circulating worldwide and may have gained a selective advantage in migratory birds, thus posing a serious threat to wild birds and potentia...
Nigerian Veterinary Journal, 2018
Highly pathogenic avian influenza H5N1 was detected for the first time in Nigeria and Africa in 2006. The source of the outbreak was not immediately clear, but scientific opinions favoured multiple introductions. The need to evaluate available epidemiological and virological data to demonstrate most probable source of introduction is important for focused control efforts. In this study, we described ten years (2006-2016) scientific observations available through ecology, epidemio-surveillance and molecular virology of avian influenza in Nigeria. Nigeria is geographically located in the tropical humid region with abundant wetlands presenting ideal ambience for birdlife. Ornithological evidence also showed that the country lies in the path of two major migratory flyways from Europe and Asia providing opportunities for co-mingling of different species and age of wild birds with resident birds. Genomic characterization including phylogenetic analysis revealed a high degree of homology among virus strains isolated in Nigeria and those detected in migratory birds from Europe suggesting common source epidemic. This study agreed with postulation that migratory wild birds from Europe may be responsible for the introduction of highly pathogenic avian influenza subtype H5N1 to Nigeria. Feral waterfowls around water bodies thereafter bridge transmission to domestic poultry holdings whereas local trade and movement of poultry and poultry products may further spread infection locally. In the light of this understanding, routine risk based sentinel surveillance for avian influenza in domestic waterfowls in ecological hotspots is recommended for early detection and response thereby saving economic losses and mitigating public health emergencies.
H5N1 influenza A viruses from 2002 are highly pathogenic in waterfowl
International Congress Series, 2004
Waterfowl are the natural reservoir for all influenza A viruses, and these viruses are usually nonpathogenic in wild aquatic birds. In late 2002, an outbreak of H5N1 influenza virus caused death among waterfowl in two Hong Kong nature parks. Genetic analysis showed that these viruses were novel H5N1 genotypes. In February 2003, a closely related H5N1 was isolated from human patients. This study aims to answer two questions: (1) Are the novel H5N1 antigenically different from the H5N1 viruses of 1997 and 2001? (2) Are they more pathogenic to ducks than previous genotypes? Antigenic analysis of the new isolates showed a different reactivity pattern from previous H5N1 isolates, suggesting antigenic drift has occurred. The new 2002 isolates caused acute disease in mallard ducks, including severe neurological symptoms and death. In contrast, previous H5N1 isolates and a 2003 human isolate did not cause any disease. Since 1961, this is the first time that influenza virus is reported to kill wild aquatic birds.
Scientific Reports, 2016
A novel highly pathogenic avian influenza virus belonging to the H5 clade 2.3.4.4 variant viruses was detected in North America in late 2014. Motivated by the identification of these viruses in domestic poultry in Canada, an intensive study was initiated to conduct highly pathogenic avian influenza surveillance in wild birds in the Pacific Flyway of the United States. A total of 4,729 hunter-harvested wild birds were sampled and highly pathogenic avian influenza virus was detected in 1.3% (n = 63). Three H5 clade 2.3.4.4 subtypes were isolated from wild birds, H5N2, H5N8, and H5N1, representing the wholly Eurasian lineage H5N8 and two novel reassortant viruses. Testing of 150 additional wild birds during avian morbidity and mortality investigations in Washington yielded 10 (6.7%) additional highly pathogenic avian influenza isolates (H5N8 = 3 and H5N2 = 7). The geographically widespread detection of these viruses in apparently healthy wild waterfowl suggest that the H5 clade 2.3.4.4 variant viruses may behave similarly in this taxonomic group whereby many waterfowl species are susceptible to infection but do not demonstrate obvious clinical disease. Despite these findings in wild waterfowl, mortality has been documented for some wild bird species and losses in US domestic poultry during the first half of 2015 were unprecedented. Avian influenza viruses (AIV) have been identified in more than 100 wild bird species 1 and Anseriformes (ducks, geese, and swans) and Charadriiformes (gulls, terns, and waders) are considered to be the primary wild reservoirs for these viruses. Wild birds infected with AIVs often display no signs of clinical disease, although this can vary widely based on the bird species and virus subtype involved. The classification of AIVs as high pathogenic or low pathogenic is based on the lethality of the virus in chickens 2. Highly pathogenic avian influenza viruses (HPAIV) often cause substantial mortality in chickens, other domestic birds, and in some cases, wild avian species, although HPAIVs are not thought to persist or circulate widely in wild birds 3. Low pathogenic H5 and H7 influenza subtypes have the ability to evolve into HPAIVs that are lethal in domestic poultry 1,4-7 and so these subtypes are of particular concern because of their potential to cause large scale avian mortality and economic losses. In early 2014, the Republic of Korea reported the occurrence of an H5 clade 2.3.4.4 HPAIV in domestic poultry and wild waterfowl 5. Although the H5N8 virus was novel, the H5 gene of this virus was determined to be a descendent of the highly pathogenic H5N1 virus first detected in China in 1996 (Goose/Guangdong/96 lineage) 8 .
Archives of Virology, 2010
We undertook one of the most comprehensive studies on the replication and intraspecies transmission characteristics of low-pathogenicity avian influenza viruses in ducks, chickens and turkeys. Our results indicated that most of these isolates could replicate and be transmitted in poultry without inducing clinical disease. However, differences in transmission to contact control birds were noted, emphasizing the importance of having contact control cage mates in biological characterization experiments. Ducks supported the replication of viruses of wild aquatic bird origin in their respiratory and digestive tracts equally well. The viruses from wild aquatic birds were not effectively transmitted among chickens. In contrast, the wild-bird isolates and viruses of domestic bird origin from live-bird markets and commercial poultry operations replicated and were transmitted more efficiently in turkeys than in chickens or ducks. We also found a lower minimal infectious dose requirement for infection of turkeys compared to chickens and ducks. Our data support an important role of turkeys as being more susceptible hosts for avian influenza viruses than domestic ducks and chickens. These results highlight the role of turkeys as intermediate or bridging hosts in the transmission of influenza viruses from wild birds to land-based domestic poultry or among different land-based bird species.