Spread Of Avian Influenza Virus Research Articles

A decision support framework for prediction of avian influenza

For years, avian influenza has influenced economies and human health around the world. The emergence and spread of avian influenza virus have been uncertain and sudden. The virus is likely to spread through several pathways such as poultry transportation and wild bird migration. The complicated and global spread of avian influenza calls for surveillance tools for timely and reliable prediction of disease events. These tools can increase situational awareness and lead to faster reaction to events. Here, we aimed to design and evaluate a decision support framework that aids decision makers by answering their questions regarding the future risk of events at various geographical scales. Risk patterns were driven from pre-built components and combined in a knowledge base. Subsequently, questions were answered by direct queries on the knowledge base or through a built-in algorithm. The evaluation of the system in detecting events resulted in average sensitivity and specificity of 69.70% and 85.50%, respectively. The presented framework here can support health care authorities by providing them with an opportunity for early control of emergency situations.

Optimal control of an avian influenza model with multiple time delays in state and control variables

In this paper, we consider an optimal control model governed by a class of delay differential equation, which describe the spread of avian influenza virus from the poultry to human. We take three control variables into the optimal control model, namely: slaughtering to the susceptible and infected poultry ( \begin{document}$ u_{1}(t) $\end{document} ), educational campaign to the susceptible human population ( \begin{document}$ u_{2}(t) $\end{document} ) and treatment to infected population ( \begin{document}$ u_{3}(t) $\end{document} ). The model involves two time delays that stand for the incubation periods of avian influenza virus in the infective poultry and human populations. We derive first order necessary conditions for existence of the optimal control and perform several numerical simulations. Numerical results show that different control strategies have different effects on controlling the outbreak of avian influenza. At the same time, we discuss the influence of time delays on objective function and conclude that the spread of avian influenza will slow down as the time delays increase.

Lactobacillus plantarum surface-displayed influenza antigens (NP-M2) with FliC flagellin stimulate generally protective immune responses against H9N2 influenza subtypes in chickens

The H9N2 avian influenza virus (AIV) causes serious economic losses to the poultry industry every year. Vaccines that induce a mucosal immune response may be successful against influenza virus infection because its transmission occurs primarily in the mucosa. To develop novel and potent oral vaccines based on Lactobacillus plantarum (L. plantarum) to control the spread of AIV in poultry industry, in the present study, we constructed and expressed fusions of the influenza antigens NP and M2 with the Salmonella Typhimurium flagellinprotein FliC on the surface of L. plantarum. Oral immunization of chicks was performed, and serum antibodies, mucosal antibodies, and specific cellular immunity were detected. Immunizing chicks with avian influenza virus was evaluated. The results showed high levels of IgG in addition to high levels of secretory immunoglobulin A (sIgA) in chickens orally administered recombinant L. plantarum. In addition, the fusion may significantly increase the levels of NP- and M2-specific T cell-mediated immunity in the case of mucosal administration of NC8-pSIP409-pgsA'-NP-M2-FliC. Recombinant NC8-pSIP409-pgsA'-NP-M2-FliC mediated effectively protected chickens against influenza virus and reduced virus titers in the lung. Our study outcomes indicate that the expression of influenza NP-M2 and a mucosal adjuvant (FliC), by L. plantarum could generate a mucosal vaccine candidate for animals in the future to defend against AIVs.

Factors influencing chicken farmers' decisions to implement prevention and control measures to reduce avian influenza virus spread under endemic conditions.

The ongoing circulation of Highly Pathogenic Avian Influenza (HPAI) H5N1 poses a threat to both poultry and public health. Adapting the constructs of the Health Belief Model (HBM) framework, we investigated perceptions of backyard, commercial broiler and layer chicken farmers to implement HPAI prevention and control measures in Bangladesh. Two cross-sectional studies were conducted in 2016 and 2017 on 144 backyard, 106 broiler and 113 layer chicken farms. Using Structural Equation Modelling, we modelled the direct and indirect effects on farmers' perceptions on taking HPAI prevention and control actions. Our results indicate that farmers of different chicken production systems have different decision-making processes. While perceived barriers to the implementation of prevention and control measures (e.g. wearing protective equipment when handling chickens) prevented both broiler and backyard farmers to adopt interventions, perceived benefits of measures (e.g. maintaining high biosecurity will reduce the risk of birds becoming sick) strongly influenced commercial farmers' decisions, but not backyard farmers' decisions. Information provided on HPAI through media, meetings or via information campaigns played an important role in farmers' decision-making in all production systems. Outcomes of this research can be used to tailor advice on HPAI control and prevention to different poultry farming groups by accounting for specific factors influencing their decision-making, instead of using one-size-fit-all communication approach.

Ecological factors associated with persistent circulation of multiple highly pathogenic avian influenza viruses among poultry farms in Taiwan during 2015-17.

Emergence and intercontinental spread of highly pathogenic avian influenza A (HPAI) H5Nx virus clade 2.3.4.4 has resulted in substantial economic losses to the poultry industry in Asia, Europe, and North America. The long-distance migratory birds have been suggested to play a major role in the global spread of avian influenza viruses during this wave of panzootic outbreaks since 2013. Poultry farm epidemics caused by multiple introduction of different HPAI novel subtypes of clade 2.3.4.4 viruses also occurred in Taiwan between 2015 and 2017. The mandatory and active surveillance detected H5N3 and H5N6 circulation in 2015 and 2017, respectively, while H5N2 and H5N8 were persistently identified in poultry farms since their first arrival in 2015. This study intended to assess the importance of various ecological factors contributed to the persistence of HPAI during three consecutive years. We used satellite technology to identify the location of waterfowl flocks. Four risk factors consistently showed strong association with the spatial clustering of H5N2 and H5N8 circulations during 2015 and 2017, including high poultry farm density (aOR:17.46, 95%CI: 5.91-74.86 and 8.23, 95% CI: 2.12-54.86 in 2015 and 2017, respectively), poultry heterogeneity index (aOR of 12.28, 95%CI: 5.02-31.14 and 2.79, 95%CI: 1.00-7.69, in 2015 and 2017, respectively), non-registered waterfowl flock density (aOR: 6.8, 95%CI: 3.41-14.46 and 9.17, 95%CI: 3.73-26.20, in 2015 and 2017, respectively) and higher percentage of cropping land coverage (aOR of 1.36, 95%CI: 1.10-1.69 and 1.04, 95%CI: 1.02-1.07, in 2015 and 2017, respectively). Our study highlights the application of remote sensing and clustering analysis for the identification and characterization of environmental factors in facilitating and contributing to the persistent circulation of certain subtypes of H5Nx in poultry farms in Taiwan.

Genetic Characterization of a Novel North American-Origin Avian Influenza A (H6N5) Virus Isolated from Bean Goose of South Korea in 2018.

The complex overlap in waterfowl migratory pathways across the world has established numerous occurrences of genetic reassortment and intercontinental spread of avian influenza virus (AIV) over long distances, thereby calling for huge efforts and targeted surveillance for infection control. During annual surveillance in South Korea in 2018, a novel avian influenza H6N5 (K6) subtype was isolated from the fecal sample of wild bird. Genomic characterization using a phylogenetic tree indicated the K6 virus to be of North American-origin, with partial homology to an H6N5 strain, A/Aix galericulata/South Korea/K17-1638-5/2017 (K17). A monobasic residue at the HA cleavage site and absence of a notable mutation at the HA receptor-binding site suggested the isolate to be of low pathogenicity. However, molecular analysis revealed the E119V mutation in the NA gene and a human host marker mutation E382D in the polymerase acidic (PA) gene, implying their susceptibility to neuraminidase inhibitors and potential infectivity in humans, respectively. For comparison, K6 and K17 were found to be dissimilar for various mutations, such as A274T of PB2, S375N/T of PB1, or V105M of NP, each concerning the increased virulence of K6 in mammalian system. Moreover, kinetic data presented the highest viral titer of this H6N5 isolate at 106.37 log10TCID50 after 48 h of infection, thus proving efficient adaptability for replication in a mammalian system in vitro. The mouse virus challenge study showed insignificant influence on the total body weight, while viral load shedding in lungs peaked at 1.88 ± 0.21 log10 TICD50/mL, six days post infection. The intercontinental transmission of viruses from North America may continuously be present in Korea, thereby providing constant opportunities for virus reassortment with local resident AIVs; these results hint at the increased potential risk of host jumping capabilities of the new isolates. Our findings reinforce the demand for regular surveillance, not only in Korea but also along the flyways in Alaska.

Overview of the Epizootiological Situation on Highly Pathogenic Avian Influenza Virus in Russia in 2019

This review describes the current situation on highly pathogenic avian influenza virus in 2019 and predicts the possible further spread of avian influenza in Russia. In 2019 outbreaks were reported among wild birds and poultry, as well as human infections with influenza viruses of the subtypes H5Nx, H7N9 and H9N2 in several countries. In 2019, only two outbreaks of highly pathogenic avian influenza H5N8 in Russia occurred. Both outbreaks were recorded in January at poultry farm in the Rostov Region. In addition, in May 2019 avian influenza virus of H14N7 subtype was isolated from a wild bird during the avian influenza virus surveillance in Tomsk Region. In June 2019, a strain of H13N2 subtype was isolated in the territory of Kamchatka Region, then, in August 2019, an influenza virus of H13N6 subtype was isolated in the Saratov Region. It was revealed that some strains of avian influenza virus isolated in Russia have a high degree of identity with strains circulating in South-East Asia. This was shown by the phylogenetic analysis of A/ H5Nx influenza viruses previously isolated in the Saratov Region and the Socialist Republic of Vietnam during the avian influenza virus surveillance. Thus, it was demonstrated again that the territory of Russia plays a key geographical role in the global spread of avian influenza virus.

Epidemiological and genetic characteristics of H5 subtype avian influenza virus in Guangzhou, 2014-2019

Objective: To analyze the characteristics of spread and genetic evolution of H5 subtype avian influenza virus in Guangzhou from 2014 to 2019. Methods: H5 subtype virus was detected by fluorescence quantitative RT-PCR from the environmental samples in Guangzhou poultry markets. The genes of HA and NA of 48 isolates randomly selected were sequenced, including 46 isolates from environmental samples and 2 isolates from cases. The characteristics of molecular variation and genetic evolution were analyzed by using bioinformatics software. Results: A total of 1 094 strains of H5 subtype avian influenza virus were isolated from 52 284 samples (2.09%). All the strains belonged to Clade 2.3.4.4.C. NA gene belonged to H6N6 of Eurasian lineage. The cleavage sites of all the strains showed the characteristics of highly pathogenicity. Receptor binding sites were avian-derived receptors. However, mutations of S123P, S133A and T156A occurred, which implied that these strains could tend to bind to human receptors. There was an additional glycosylation site at 140 in strains isolated after 2017. The variation of antigen loci mainly occurred in B and E regions. Conclusions: H5 subtype avian influenza virus spread in Guangzhou from 2014 to 2019 with annual increased proportion of positive rate, and the sequencing results indicated that it belonged to Clade 2.3.4.4.C of H5N6 highly pathogenic virus, and genetic evolution and mutation continued, especially the common mutations which could enhance the binding capacity to human receptors. It is necessary to strengthen the surveillance.

Pathological and Molecular Characterization of H5 Avian Influenza Virus in Poultry Flocks from Egypt over a Ten-Year Period (2009-2019).

Simple SummaryAvian influenza virus (H5) remains one of the challenging zoonotic viruses in Egypt. Our study investigated the occurrence of this virus among chickens from Dakhalia governorate, Egypt over ten years through histopathological examination and molecular characterization of the virus. The molecular characterization was followed by sequencing and phylogenetic analysis of the positive samples. Importantly, we have reported several interesting pathological changes and high occurrence of the H5 avian influenza virus, the phylogenetic analysis revealed that positive samples were aligned with several Egyptian sub clades. Clearly, our study concludes the widespread of the virus among poultry flocks in Egypt and suggests further future research aims to develop an efficient surveillance program with investigation into the effectiveness of the implemented control measures for controlling this disease of public health concern.Avian influenza virus (AIV) remains one of the enzootic zoonotic diseases that challenges the poultry industry in Egypt. In the present study, a total of 500 tissue samples were collected from 100 chicken farms (broilers and layers) suspected to be infected with AIV through the period from 2009 to 2019 from Dakahlia governorate, Egypt. These samples were pooled in 100 working samples and screened for AIV then the positive samples were subjected to histopathological examination combined with real time-polymerase chain reaction (RRT-PCR). RRT-PCR positive samples were also subjected to conventional reverse transcriptase-polymerase chain reaction (RT-PCR) for detection of H5 AIV and some of these resulting positive samples were sequenced for detection of the molecular nature of the studied virus. Interestingly, the histopathological examination revealed necrotic liver with leukocytic infiltration with degenerative changes with necrotic pancreatitis, edema, and intense lymphoid depletion of splenic tissue and hyperplastic tracheal epithelium. Likewise, edema and congested sub mucosal blood vessels and intense bronchial necrosis with hyalinized wall vascular wall and heterophils infiltration were reported. Pneumonic areas with intense leukocytic aggregation mainly and vasculitis of the pulmonary blood vessels were also detected in lung. Collectively, these significant pathological changes in examined tissues cohered with AIV infection. Regarding the molecular characterization, 66 samples were positive for AIV by RRT-PCR and 52 of them were positive for H5 AIV by RT-PCR. The phylogenetic analysis revealed that the H5 viruses identified in this study were aligned with other Egyptian H5N1 AIVs in the Egyptian sub clade 2.2.1, while some of the identified strains were aligned with other Egyptian H5N8 strains in the new Egyptian sub clade 2.3.4.4. Taken together, our present findings emphasize the wide spread of AIV in Egypt and the importance of developing an efficient surveillance and periodical screening program for controlling such disease of public health concern.

The Presence of Poultry Influenza Strains in Two Live Bird Markets near the East-West Boundary of Vietnam.

The spread of avian influenza virus among Asian countries is becoming a concern after influenza epidemics in recent years. This study is aimed at identifying the subtypes of avian influenza viruses collected from healthy chickens and ducks at two live bird markets in a border province of Vietnam and the Lao People Democratic Republic. Cloacal and tracheal swab samples from 100 chickens and 101 ducks were collected in May 2017. All samples were screened to detect avian influenza virus by real-time reverse transcriptase PCR. Samples that are avian influenza virus-positive were isolated in embryonated chicken eggs, and the subtypes were identified by RT-PCR with the specific primers. The samples positive for influenza virus H5 were sequenced to identify HA and NA genes. The prevalence of avian influenza virus (AIV) among chicken and duck samples was 27.5% (55/200) and 24.8% (50/202), respectively. AIV subtypes identified among 17 samples positive with the hemagglutination test include H3N6, H6N6, and H9N2. Of these 17 samples, 7 duck samples were found to be H6N6, 4 duck samples were infected with both subtypes of H3N6 and H6N6, and two chicken samples were recorded as H9N2. A positive chicken sample with A/H5 contains 99% similarity nucleotide with H5N6 reference strain. Results suggested that while the presence of low pathogenic avian influenza virus is predominant, potential risks of the appearance of high pathogen avian influenza virus in the east-west boundary in Vietnam should be concerned and studied further. Furthermore, prevention activities are needed to reduce such biosecurity threats in Vietnam and other Asian countries.

The Immunogenicity And Protective Efficacy Of Dna Vaccine Coding For Na1 Gene Of Highly Pathogenic Avian Influenza H5n1 Subtype

Control of avian influenza infection depends mainly on biosafety measures and vaccination, DNA vaccination is a novel method to generate antigen-specific antibody and cell-mediated immunity. In the current study, a DNA vaccine for a full-length N1 gene was developed in a trial to decrease the severity of the avian influenza virus spread and shedding. THE full-length N1 gene was cloned in entry clone p ENTER SD/TOPO, followed by homologous recombination with the destination mammalian expression vector (PDEST 40). The PDEST 40-N1 was used in the immunization of SPF chickens. Potency was evaluated through the survival rate that reaches 65%, which was far less than the commercially available inactivated vaccine. Meanwhile, the shedding of the virus from dead birds was 0.46 Log 10 EID50. At the same time, the most surprising result was the shedding level of the vaccinated live birds that were zero sheddings;on the other hand, the inactivated vaccine could not reduce the shedding level which remains very high (3.2 Log 10 EID50 ). IFN-γ transcript level in the DNA vaccinated group was detected by the 3rd-day post-vaccination and remained upregulated till the 28th post-vaccination. After the challenge, the level of IFN-γ was much higher until 14 days post-challenge. The inactivated vaccine could not stimulate any detectable level post-vaccination. These data suggested the ability of DNA vaccine coding for N1 gene of avian influenza to combat the virus shedding from live birds and could be used in combination with DNA vaccine coding for H5 to produce maximum protection with zero sheddings.

Knowledge and remaining gaps on the role of animal and human movements in the poultry production and trade networks in the global spread of avian influenza viruses - A scoping review.

Poultry production has significantly increased worldwide, along with the number of avian influenza (AI) outbreaks and the potential threat for human pandemic emergence. The role of wild bird movements in this global spread has been extensively studied while the role of animal, human and fomite movement within commercial poultry production and trade networks remains poorly understood. The aim of this work is to better understand these roles in relation to the different routes of AI spread. A scoping literature review was conducted according to the PRISMA guidelines (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) using a search algorithm combining twelve domains linked to AI spread and animal/human movements within poultry production and trade networks. Only 28 out of 3,978 articles retrieved dealt especially with the role of animal, human and fomite movements in AI spread within the international trade network (4 articles), the national trade network (8 articles) and the production network (16 articles). While the role of animal movements in AI spread within national trade networks has been largely identified, human and fomite movements have been considered more at risk for AI spread within national production networks. However, the role of these movements has never been demonstrated with field data, and production networks have only been partially studied and never at international level. The complexity of poultry production networks and the limited access to production and trade data are important barriers to this knowledge. There is a need to study the role of animal and human movements within poultry production and trade networks in the global spread of AI in partnership with both public and private actors to fill this gap.

Control of avian influenza in China: Strategies and lessons.

In recent decades, multiple subtypes (i.e. H9N2, H5N1 and H7N9) of avian influenza virus (AIV) have become widespread in China, which has caused enormous economic losses and posed considerable threats to public health. In this review, with the aim to provide insights into and guidelines for the control of AIV spread in China and globally in the future, we analysed the reasons why AIV has persisted in China based on socio-economic features, including poultry biosecurity, live bird markets, live bird transportation, wild birds, poultry waterfowl, poultry density, poultry population and infected birds. We also described the present status of the AIV subtypes H9, H5 and H7 in China to elucidate the effectiveness of the strategies currently employed in China (i.e. culling, mass vaccination and biosecurity improvement) to control the disease based on a literature review and our unpublished surveillance data collected over a 12-year period from 2007 to 2018. We then summarized the lessons to be learned from the control experience in China, including whether culling of infected birds is of limited value for disease control and whether improved biosecurity is a better option than culling and vaccination for the long-term control of AIV, and when the vaccine strain should be updated.

Protective efficacy in farmed ducks of a duck enteritis virus-vectored vaccine against H5N1, H5N6, and H5N8 avian influenza viruses

Ducks play a key role in the maintenance and spread of avian influenza viruses (AIVs) in nature, and control of AIVs in ducks has important implications for AIV eradication from poultry. We previously constructed a recombinant duck enteritis virus (DEV), rDEVus78HA, that expresses the HA gene of an H5N1 AIV and showed that rDEVus78HA immunization provides complete protection against both DEV and H5N1 AIV challenge in specific-pathogen-free ducks. In this study, we performed a 60-week clinical trial and found that this rDEVus78HA vaccine can function as a bivalent vaccine in farmed ducks against lethal challenge with DEV and H5N1 virus. Moreover, we found that rDEVus78HA-vaccinated ducks were efficiently protected against challenges with recently isolated heterologous H5N6 and H5N8 viruses. Our results demonstrate that rDEVus78HA could be extremely valuable for the control of DEV and H5 AIVs in ducks.

Intercontinental spread of Asian-origin H7 avian influenza viruses by captive bird trade in 1990's

Wild bird migration and illegal trade of infected poultry, eggs, and poultry products have been associated with the spread of avian influenza viruses (AIV). During 1992–1996, H7N1 and H7N8 low pathogenic AIV (LPAIV) were identified from captive wild birds; such as Pekin robin (Leiothrix lutea), magpie robin (Copsychus saularis), flycatcher sp. (genus Empidonax), a species of softbill and parakeet, sun conure (Aratinga solstitialis), painted conure (Pyrrhura picta), fairy bluebird (Irena puella), and common iora (Aegithina tiphia), kept in aviaries or quarantine stations in England, The Netherlands, Singapore and the United States (U.S.). In this study, we sequenced these H7 viruses isolated from quarantine facilities and aviaries using next-generation sequencing and conducted a comparative phylogenetic analysis of complete genome sequences to elucidate spread patterns. The complete genome sequencing and phylogenetic analysis suggested that H7 viruses originated from a common source, even though they were obtained from birds in distant geographical regions. All H7N1 and H7N8 viruses were LPAIV, except a H7N1 highly pathogenic AIV (HPAIV), A/Pekin robin/California/30412/1994(H7N1) virus. Our results support the continued need for regulation of the captive wild bird trade to reduce the risk of introduction and dissemination of both LPAIV and HPAIV throughout the world.

ANALYSIS OF MIGRATION OF AQUATIC AND SEMIAQUATIC BIRDS ON THE TERRITORY OF THE REPUBLIC OF DAGESTAN AND JUSTIFICATION OF THE CHOICE OF KEY POINTS OF MONITORING OF INFLUENZA A VIRUS

Aim. The aim of the work is to carry out an analysis of the wetlands of the Republic of Dagestan in order to justify the selection of the collecting sites for material from migratory aquatic and semi aquatic birds in order to monitor the influenza A virus.Material and methods. Studying scientific publications of different years and available information on the wetlands of the Caspian Dagestan allowed establishing the areas of concentration of aquatic and semiaquatic birds where effective sampling for avian influenza is possible.Results. The spread of avian influenza viruses in nature is inextricably linked with migration of birds. Due to the presence of a large number of reservoirs, the western part of the Caspian region brings together large populations of wild waterbirds from various places within their migration routes. Mass accumulation encourages the interaction of birds of different species and populations, which in turn creates favorable conditions for the spread of various viral diseases.Conclusion. For an integrated assessment of the state of aquatic and semiaquatic bird populations, as well as monitoring the avian influenza infection rates, it is proposed to consider as model areas the wetlands of the Lake Aji (Papas), Lake Yuzhny Agrakhan, Agrakhansky Gulf, the Terek River delta and the Achikolsky systems of lake.

Overview of the Epidemiological Situation on Highly Pathogenic Avian Influenza Virus in Russia in 2018

Analyzed was modern epidemiological situation on highly pathogenic avian flu in 2018. Prognosis for possible further distribution of viruses in the territory of Russia was made. In 2018, the situation on highly pathogenic avian flu in Russia was challenging. This was due to the spread of the viruses clade 2.3.4.4, which caused multiple outbreaks among wild birds and poultry in European part of Russia. In addition, A/H5N6 avian influenza virus circulation was for the first time detected in the Saratov Region during routine avian influenza virus surveillance. In May, 2018 two different lineages of avian influenza A/H9N2 were isolated during the outbreaks that occurred at several poultry plants in Primorsk Territory and Amur Region of Russia. Subsequently, that virus subtype continued spreading in Russia, which was recorded by detection of the A/H9N2 influenza virus in wild birds in the Khabarovsk and Tomsk Regions of Russia. Thus, it is shown yet again that the territory of Russia plays an important geographical role in the spread of avian influenza viruses.

Recent Advances in AIV Biosensors Composed of Nanobio Hybrid Material.

Since the beginning of the 2000s, globalization has accelerated because of the development of transportation systems that allow for human and material exchanges throughout the world. However, this globalization has brought with it the rise of various pathogenic viral agents, such as Middle East respiratory syndrome coronavirus (MERS-CoV), severe acute respiratory syndrome coronavirus (SARS-CoV), Zika virus, and Dengue virus. In particular, avian influenza virus (AIV) is highly infectious and causes economic, health, ethnical, and social problems to human beings, which has necessitated the development of an ultrasensitive and selective rapid-detection system of AIV. To prevent the damage associated with the spread of AIV, early detection and adequate treatment of AIV is key. There are traditional techniques that have been used to detect AIV in chickens, ducks, humans, and other living organisms. However, the development of a technique that allows for the more rapid diagnosis of AIV is still necessary. To achieve this goal, the present article reviews the use of an AIV biosensor employing nanobio hybrid materials to enhance the sensitivity and selectivity of the technique while also reducing the detection time and high-throughput process time. This review mainly focused on four techniques: the electrochemical detection system, electrical detection method, optical detection methods based on localized surface plasmon resonance, and fluorescence.

Identifying key bird species and geographical hotspots of avian influenza A (H7N9) virus in China

BackgroundIn China since the first human infection of avian influenza A (H7N9) virus was identified in 2013, it has caused serious public health concerns due to its wide spread and high mortality rate. Evidence shows that bird migration plays an essential role in global spread of avian influenza viruses. Accordingly, in this paper, we aim to identify key bird species and geographical hotspots that are relevant to the transmission of avian influenza A (H7N9) virus in China.MethodsWe first conducted phylogenetic analysis on 626 viral sequences of avian influenza A (H7N9) virus isolated in chicken, which were collected from the Global Initiative on Sharing All Influenza Data (GISAID), to reveal geographical spread and molecular evolution of the virus in China. Then, we adopted the cross correlation function (CCF) to explore the relationship between the identified influenza A (H7N9) cases and the spatiotemporal distribution of migratory birds. Here, the spatiotemporal distribution of bird species was generated based on bird observation data collected from China Bird Reports, which consists of 157 272 observation records about 1145 bird species. Finally, we employed a kernel density estimator to identify geographical hotspots of bird habitat/stopover that are relevant to the influenza A (H7N9) infections.ResultsPhylogenetic analysis reveals the evolutionary and geographical patterns of influenza A (H7N9) infections, where cases in the same or nearby municipality/provinces are clustered together with small evolutionary differences. Moreover, three epidemic waves in chicken along the East Asian–Australasian flyway in China are distinguished from the phylogenetic tree. The CCF analysis identifies possible migratory bird species that are relevant to the influenza A(H7N9) infections in Shanghai, Jiangsu, Zhejiang, Fujian, Jiangxi, and Guangdong in China, where the six municipality/provinces account for 91.2% of the total number of isolated H7N9 cases in chicken in GISAID. Based on the spatial distribution of identified bird species, geographical hotspots are further estimated and illustrated within these typical municipality/provinces.ConclusionsIn this paper, we have identified key bird species and geographical hotspots that are relevant to the spread of influenza A (H7N9) virus. The results and findings could provide sentinel signal and evidence for active surveillance, as well as strategic control of influenza A (H7N9) transmission in China.

Bioaerosol Sampling to Detect Avian Influenza Virus in Hanoi's Largest Live Poultry Market.

Newly emergent and virulent strains of H7N9 avian influenza virus are rapidly spreading in China and threaten to invade Vietnam. We sought to introduce aerosol sampling for avian influenza viruses in Vietnam. During October 2017, National Institute for Occupational Safety and Health 2-stage aerosol samplers were assembled on a tripod and run for 4 hours. Concomitantly, up to 20 oropharyngeal (OP) swab samples were collected from chickens and ducks distanced at 0.2-1.5 m from each sampler. The 3 weeks of sampling yielded 30 aerosol samples that were 90% positive for influenza A, by quantitative reverse-transcription polymerase chain reaction, and 116 OP swab sample pools (5 samples per pool) that were 47% positive. Egg cultures yielded 1 influenza A virus (not H5 or H7) from aerosol and 25 influenza A viruses from OP swab sample pools (5 were H5 positive). The association between positive sample types (over time and position) was strong, with 91.7% of positive OP pooled swab samples confirmed by positive aerosol samples and 81% of influenza A positive aerosol samples confirmed by positive OP swab samples. We posit that aerosol sampling might be used for early warning screening of poultry markets for novel influenza virus detection, such as H7N9. Markets with positive aerosol samples might be followed up with more focused individual bird or cage swabbing, and back-tracing could be performed later to locate specific farms harboring novel virus. Culling birds in such farms could reduce highly pathogenic avian influenza virus spread among poultry and humans.