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Situation-Based Survey of Avian Influenza Viruses in Possible “Bridge” Species of Wild and Domestic Birds in Nigeria  [PDF]
Vakuru Columba Teru,Shiiwua A. Manu,Gashash I. Ahmed,Kabir Junaidu,Scott Newman,Joseph Nyager,Vivian N. Iwar,Gideon M. Mshelbwala,T. Joannis,Junaidu A. Maina,Paul T. Apeverga
Influenza Research and Treatment , 2012, DOI: 10.1155/2012/567601
Abstract: The highly pathogenic avian influenza (H5N1 subtype) recurred in Nigeria after 9 months period of no reported case. A critical look at possible sources of the re-occurrence was desirable. The objective of this study was to determine whether avian influenza viruses were present at reasonably detectable levels (0.5%) in possible “bridge” species of wild and domestic birds. The study was conducted in 8 Nigerian states. A total of 403 birds from 40 species were sampled. Virus isolation was done in embryonated chicken eggs according to standard protocols. The test results were all negative for avian influenza viruses. The overall confidence interval (CI) calculated in R using the exact binomial confidence interval function was 0–0.007406. Tawny Eagle (Aquila rapax) was the lowest sampled 0.3% (1/403) and Red-billed Firefinch (Lagonosticta senegala) the highest 11.7% (47/403). The limitations of the sample size and possibly designing effects on the study, as to make concrete conclusions were acknowledged. Species of wild birds, so identified in the study could be useful in future surveys. Furthermore, multidisciplinary and community oriented approach, blending targeted and passive surveillances was suggested. This approach was envisaged to bring about wider coverage of “bridge” species and clearer insight of their possible roles in avian influenza re-occurrences and spread in Nigeria. 1. Introduction Avian influenza (AI) is a highly contagious disease primarily of birds, and caused by influenza A viruses. Influenza A viruses in poultry can be grouped into 2. The exceptionally virulent viruses cause highly pathogenic avian influenza (HPAI), with mortality in affected flock as high as 100%. This group belongs to subtypes H5 and H7, but it is worth noting that not all H5 and H7 viruses’ infection lead to HPAI. All other subtypes cause a milder, primarily respiratory, disease, that is, low pathogenic avian influenza (LPAI) unless exacerbated by secondary infections [1]. Avian influenza is one of the greatest concerns for public health that has emerged from the animal reservoir [2]. The spread of HPAI (H5N1) to countries in which hygienic standards are deficient increases the virus’s pandemic potential and raises concerns about food security particularly in rural villages [2]. Aquatic birds are the sources of avian influenza viruses [3, 4]. Aquatic birds like ducks, geese, swans (Anseriformes), and gulls, terns (Charadriiforms) are thought to be natural reservoirs for avian influenza viruses and are capable of shading the viruses asymptomatically [5, 6]. HPAI
Investigation of Avian Influenza Infections in Wild Birds, Poultry and Humans in Eastern Dongting Lake, China  [PDF]
Jinghong Shi, Lidong Gao, Yun Zhu, Tao Chen, Yunzhi Liu, Libo Dong, Fuqiang Liu, Hao Yang, Yahui Cai, Mingdong Yu, Yi Yao, Cuilin Xu, Xiangming Xiao, Yuelong Shu
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0095685
Abstract: We investigated avian influenza infections in wild birds, poultry, and humans at Eastern Dongting Lake, China. We analyzed 6,621 environmental samples, including fresh fecal and water samples, from wild birds and domestic ducks that were collected from the Eastern Dongting Lake area from November 2011 to April 2012. We also conducted two cross-sectional serological studies in November 2011 and April 2012, with 1,050 serum samples collected from people exposed to wild birds and/or domestic ducks. Environmental samples were tested for the presence of avian influenza virus (AIV) using quantitative PCR assays and virus isolation techniques. Hemagglutination inhibition assays were used to detect antibodies against AIV H5N1, and microneutralization assays were used to confirm these results. Among the environmental samples from wild birds and domestic ducks, AIV prevalence was 5.19 and 5.32%, respectively. We isolated 39 and 5 AIVs from the fecal samples of wild birds and domestic ducks, respectively. Our analysis indicated 12 subtypes of AIV were present, suggesting that wild birds in the Eastern Dongting Lake area carried a diverse array of AIVs with low pathogenicity. We were unable to detect any antibodies against AIV H5N1 in humans, suggesting that human infection with H5N1 was rare in this region.
First introduction of highly pathogenic H5N1 avian influenza A viruses in wild and domestic birds in Denmark, Northern Europe
Karoline Bragstad, Poul H J?rgensen, Kurt Handberg, Anne S Hammer, Susanne Kabell, Anders Fomsgaard
Virology Journal , 2007, DOI: 10.1186/1743-422x-4-43
Abstract: Full-genome characterisation of nine isolates revealed that the Danish H5N1 viruses were highly similar to German H5N1 isolates in all genes from the same time period. The haemagglutinin gene grouped phylogenetically in H5 clade 2 subclade 2 and closest relatives besides the German isolates were isolates from Croatia in 2005, Nigeria and Niger in 2006 and isolates from Astrakhan in Russia 2006. The German and Danish isolates shared unique substitutions in the NA, PB1 and NS2 proteins.The first case of HP H5N1 infection of wild and domestic birds in Denmark was experienced in March 2006. This is the first full genome characterisation of HP H5N1 avian influenza A virus in the Nordic countries. The Danish viruses from this time period have their origin from the wild bird strains from Qinghai in 2005. These viruses may have been introduced to the Northern Europe through unusual migration due to the cold weather in Eastern Europe at that time.All subtypes of influenza A are perpetuated in wild aquatic birds and thereby these birds serve as a reservoir of influenza A. Avian influenza viruses (AIVs) are believed to be in evolutionary stasis in its natural hosts of wild birds where the virus and the host tolerate each other [1]. AIVs are characterised as low pathogenic (LP) or high pathogenic (HP), depending on their ability to cause disease in chickens. LP AIV may become HP to poultry through mutations after introduction from wild birds. Until now, only AIV of subtypes H5 and H7 have become HP. There are currently recognised sixteen subtypes of haemagglutinin (HA) and nine neuraminidases (NAs) [2,3]. Only H3N2, H1N1 and H1N2 out of 144 theoretically possible subtype combinations circulate in humans. In Hong Kong in 1997, eighteen people became infected with HP AIV H5N1 and six died [4,5]. Before 1997, AIV was not expected to cross the species barrier and infect humans, although incidences of H7N7 infection had been seen in the past [6-8]. Prior to the outbreak in humans in
Preliminary results of an influenza surveillance in wild birds, game birds, domestic ducks and geese in North Eastern Italy
Roberta De Nardi,Calogero Terregino,Giovanni Cattoli,Anna Toffan
Italian Journal of Animal Science , 2010, DOI: 10.4081/ijas.2005.292
Abstract: Following the avian influenza (AI) epidemics which occurred in Italy between 1997 and 2003, a surveillance program, funded by the Italian Ministry of Health was implemented. Among the tasks of this surveillance program was an investigation on wild and domestic birds to asses circulation of avian influenza viruses in their natural reservoirs. In this study we collected samples from migratory wild birds (Anseriformes and Charadriiformes), from national and importated game fowls, and from 7 backyard farms of geese and ducks. Cloacal swabs were screened by means of real-time RT-PCR (RRT-PCR) and/or directly processed for attempted virus isolation in embryonated fowl’s SPF eggs and blood samples for presence of antibodies against avian influenza viruses. Avian influenza viruses were only obtained from migratory waterfowls belonging to the family Anseriformes, and not from domestic waterfowls or game birds. This study confirms that the risk of introduction of novel influenza viruses in densely populated areas of poultry farms in Veneto is linked to migratory wild birds and in particular from birds belonging to the family Anseriformes.
Different Environmental Drivers of Highly Pathogenic Avian Influenza H5N1 Outbreaks in Poultry and Wild Birds  [PDF]
Yali Si, Willem F. de Boer, Peng Gong
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0053362
Abstract: A large number of highly pathogenic avian influenza (HPAI) H5N1 outbreaks in poultry and wild birds have been reported in Europe since 2005. Distinct spatial patterns in poultry and wild birds suggest that different environmental drivers and potentially different spread mechanisms are operating. However, previous studies found no difference between these two outbreak types when only the effect of physical environmental factors was analysed. The influence of physical and anthropogenic environmental variables and interactions between the two has only been investigated for wild bird outbreaks. We therefore tested the effect of these environmental factors on HPAI H5N1 outbreaks in poultry, and the potential spread mechanism, and discussed how these differ from those observed in wild birds. Logistic regression analyses were used to quantify the relationship between HPAI H5N1 outbreaks in poultry and environmental factors. Poultry outbreaks increased with an increasing human population density combined with close proximity to lakes or wetlands, increased temperatures and reduced precipitation during the cold season. A risk map was generated based on the identified key factors. In wild birds, outbreaks were strongly associated with an increased Normalized Difference Vegetation Index (NDVI) and lower elevation, though they were similarly affected by climatic conditions as poultry outbreaks. This is the first study that analyses the differences in environmental drivers and spread mechanisms between poultry and wild bird outbreaks. Outbreaks in poultry mostly occurred in areas where the location of farms or trade areas overlapped with habitats for wild birds, whereas outbreaks in wild birds were mainly found in areas where food and shelters are available. The different environmental drivers suggest that different spread mechanisms might be involved: HPAI H5N1 spread to poultry via both poultry and wild birds, whereas contact with wild birds alone seems to drive the outbreaks in wild birds.
Highly Pathogenic Avian Influenza Virus among Wild Birds in Mongolia  [PDF]
Martin Gilbert, Losolmaa Jambal, William B. Karesh, Amanda Fine, Enkhtuvshin Shiilegdamba, Purevtseren Dulam, Ruuragchaa Sodnomdarjaa, Khuukhenbaatar Ganzorig, Damdinjav Batchuluun, Natsagdorj Tseveenmyadag, Purevsuren Bolortuya, Carol J. Cardona, Connie Y. H. Leung, J. S. Malik Peiris, Erica Spackman, David E. Swayne, Damien O. Joly
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0044097
Abstract: Mongolia combines a near absence of domestic poultry, with an abundance of migratory waterbirds, to create an ideal location to study the epidemiology of highly pathogenic avian influenza virus (HPAIV) in a purely wild bird system. Here we present the findings of active and passive surveillance for HPAIV subtype H5N1 in Mongolia from 2005–2011, together with the results of five outbreak investigations. In total eight HPAIV outbreaks were confirmed in Mongolia during this period. Of these, one was detected during active surveillance employed by this project, three by active surveillance performed by Mongolian government agencies, and four through passive surveillance. A further three outbreaks were recorded in the neighbouring Tyva Republic of Russia on a lake that bisects the international border. No HPAIV was isolated (cultured) from 7,855 environmental fecal samples (primarily from ducks), or from 2,765 live, clinically healthy birds captured during active surveillance (primarily shelducks, geese and swans), while four HPAIVs were isolated from 141 clinically ill or dead birds located through active surveillance. Two low pathogenic avian influenza viruses (LPAIV) were cultured from ill or dead birds during active surveillance, while environmental feces and live healthy birds yielded 56 and 1 LPAIV respectively. All Mongolian outbreaks occurred in 2005 and 2006 (clade 2.2), or 2009 and 2010 (clade 2.3.2.1); all years in which spring HPAIV outbreaks were reported in Tibet and/or Qinghai provinces in China. The occurrence of outbreaks in areas deficient in domestic poultry is strong evidence that wild birds can carry HPAIV over at least moderate distances. However, failure to detect further outbreaks of clade 2.2 after June 2006, and clade 2.3.2.1 after June 2010 suggests that wild birds migrating to and from Mongolia may not be competent as indefinite reservoirs of HPAIV, or that HPAIV did not reach susceptible populations during our study.
Characterization of H7 Influenza A Virus in Wild and Domestic Birds in Korea  [PDF]
Hyun-Mi Kang, Ha-Young Park, Kyu-Jun Lee, Jun-Gu Choi, Eun-Kyoung Lee, Byung-Min Song, Hee-Soo Lee, Youn-Jeong Lee
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0091887
Abstract: During surveillance programs in Korea between January 2006 and March 2011, 31 H7 avian influenza viruses were isolated from wild birds and domestic ducks and genetically characterized using large-scale sequence data. All Korean H7 viruses belonged to the Eurasian lineage, which showed substantial genetic diversity, in particular in the wild birds. The Korean H7 viruses from poultry were closely related to those of wild birds. Interestingly, two viruses originating in domestic ducks in our study had the same gene constellations in all segment genes as viruses originating in wild birds. The Korean H7 isolates contained avian-type receptors (Q226 and G228), no NA stalk deletion (positions 69–73), no C-terminal deletion (positions 218–230) in NS1, and no substitutions in PB2-627, PB1-368, and M2-31, compared with H7N9 viruses. In pathogenicity experiments, none of the Korean H7 isolates tested induced clinical signs in domestic ducks or mice. Furthermore, while they replicated poorly, with low titers (10 0.7–1.3EID50/50 μl) in domestic ducks, all five viruses replicated well (up to 7–10 dpi, 10 0.7–4.3EID50/50 μl) in the lungs of mice, without prior adaptation. Our results suggest that domestic Korean viruses were transferred directly from wild birds through at least two independent introductions. Our data did not indicate that wild birds carried poultry viruses between Korea and China, but rather, that wild-type H7 viruses were introduced several times into different poultry populations in eastern Asia.
Public Health and Epidemiological Considerations For Avian Influenza Risk Mapping and Risk Assessment  [cached]
Joseph P. Dudley
Ecology and Society , 2008,
Abstract: Avian influenza viruses are now widely recognized as important threats to agricultural biosecurity and public health, and as the potential source for pandemic human influenza viruses. Human infections with avian influenza viruses have been reported from Asia (H5N1, H5N2, H9N2), Africa (H5N1, H10N7), Europe (H7N7, H7N3, H7N2), and North America (H7N3, H7N2, H11N9). Direct and indirect public health risks from avian influenzas are not restricted to the highly pathogenic H5N1 "bird flu" virus, and include low pathogenic as well as high pathogenic strains of other avian influenza virus subtypes, e.g., H1N1, H7N2, H7N3, H7N7, and H9N2. Research has shown that the 1918 Spanish Flu pandemic was caused by an H1N1 influenza virus of avian origins, and during the past decade, fatal human disease and human-to-human transmission has been confirmed among persons infected with H5N1 and H7N7 avian influenza viruses. Our ability to accurately assess and map the potential economic and public health risks associated with avian influenza outbreaks is currently constrained by uncertainties regarding key aspects of the ecology and epidemiology of avian influenza viruses in birds and humans, and the mechanisms by which highly pathogenic avian influenza viruses are transmitted between and among wild birds, domestic poultry, mammals, and humans. Key factors needing further investigation from a risk management perspective include identification of the driving forces behind the emergence and persistence of highly pathogenic avian influenza viruses within poultry populations, and a comprehensive understanding of the mechanisms regulating transmission of highly pathogenic avian influenza viruses between industrial poultry farms and backyard poultry flocks. More information is needed regarding the extent to which migratory bird populations to contribute to the transnational and transcontinental spread of highly pathogenic avian influenza viruses, and the potential for wild bird populations to serve as reservoirs for highly pathogenic avian influenza viruses. There are still uncertainties regarding the epidemiological and ecological mechanisms that regulate "spill-over" and "spill-back" transmission of highly pathogenic avian influenza viruses between poultry and wild bird populations, and the interspecies transmission of avian influenza from infected birds to humans and other species of mammals. Further investigations are needed to evaluate the effectiveness of poultry vaccination programs for the control and eradication of avian influenza in poultry populations at the national and
Pathogens Transmitted by Migratory Birds: Threat Perceptions to Poultry Health and Production  [PDF]
K. Dhama,M. Mahendran,S. Tomar
International Journal of Poultry Science , 2008,
Abstract: The role of migrating wild birds in transmitting diseases of poultry or zoonoses is a contentious issue as the researchers and naturalists stands divided regarding their capability to disperse pathogens over continents. Recently, migratory birds got world wide attention during the bird flu outbreaks, as they were found capable to disseminate the deadly H5N1 avian influenza (bird flu) virus, without themselves getting affected. However, the death of migratory birds due to H5N1, reported from Asia, has fuelled anxiety and concern over the whole issue. Apart from avian influenza, migratory birds are also thought to play role in the transmission of avian viruses like Newcastle disease virus, avian pneumovirus and duck plague virus. Similarly, bacterial pathogens like Chlamydophila psittaci and Pasteurella multocida can be transmitted to domestic poultry via migratory birds. They are also known to spread West Nile virus, equine encephalitis virus, Borrelia burgdorferi and enteropathogens like Campylobacter and Salmonella, which could affect animals as will as human beings. To prevent such etiological agents from entering poultry premises, strict biosecurity and constant surveillance are of paramount importance. Hence, in the scenario of migratory birds contributing significantly to the global spread of infectious diseases, a better understanding of their role in the disease epidemiology has to be gained by implementing superior surveillance and tracking strategies.
Evidence of Infection by H5N2 Highly Pathogenic Avian Influenza Viruses in Healthy Wild Waterfowl  [PDF]
Nicolas Gaidet equal contributor ,Giovanni Cattoli equal contributor,Saliha Hammoumi,Scott H. Newman,Ward Hagemeijer,John Y. Takekawa,Julien Cappelle,Tim Dodman,Tony Joannis,Patricia Gil,Isabella Monne,Alice Fusaro,Ilaria Capua,Shiiwuua Manu,Pierfrancesco Micheloni,Ulf Ottosson,John H. Mshelbwala,Juan Lubroth,Joseph Domenech,Fran?ois Monicat
PLOS Pathogens , 2008, DOI: 10.1371/journal.ppat.1000127
Abstract: 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.
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