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Epidemiology and Infection Jul 2018Almost the full range of 16 haemagglutinin (HA) and nine neuraminidase subtypes of avian influenza viruses (AIVs) has been detected either in waterfowl, land-based...
Almost the full range of 16 haemagglutinin (HA) and nine neuraminidase subtypes of avian influenza viruses (AIVs) has been detected either in waterfowl, land-based poultry or in the environment in Bangladesh. AIV infections in Bangladesh affected a wide range of host species of terrestrial poultry. The highly pathogenic avian influenza (AI) H5N1 and low pathogenic AI H9N2 were found to co-circulate and be well entrenched in the poultry population, which has caused serious damage to the poultry industry since 2007. By reviewing the available scientific literature, the overall situation of AIVs in Bangladesh is discussed. All Bangladeshi (BD) H5N1 and H9N2 AIV sequences available at GenBank were downloaded along with other representative sequences to analyse the genetic diversity among the circulating AIVs in Bangladesh and to compare with the global situation. Three different H5N1 clades, 2.2.2, 2.3.2.1 and 2.3.4.2, have been detected in Bangladesh. Only 2.3.2.1a is still present. The BD LP H9N2 viruses mostly belonged to the H9 G1 lineage but segregated into many branches, and some of these shared internal genes with HP viruses of subtypes H7N3 and H5N1. However, these reassortment events might have taken place before introduction to Bangladesh. Currently, H9N2 viruses continue to evolve their HA cleavage, receptor binding and glycosylation sites. Multiple mutations in the HA gene associated with adaptation to mammalian hosts were also observed. Strict biosecurity at farms and gradual phasing out of live-bird markets could be the key measures to better control AIVs, whereas stamping out is not a practicable option in Bangladesh. Vaccination also could be an additional tool, which however, requires careful planning. Continuous monitoring of AIVs through systematic surveillance and genetic characterisation of the viruses remains a hallmark of AI control.
Topics: Animals; Bangladesh; Influenza A Virus, H5N1 Subtype; Influenza A Virus, H9N2 Subtype; Influenza in Birds; Mutation; Poultry; Poultry Diseases; Risk Factors
PubMed: 29781424
DOI: 10.1017/S0950268818001292 -
Systematic Reviews Jan 2018We conducted a systematic review to investigate avian influenza outbreaks and to explore their distribution, upon avian influenza subtype, country, avian species and...
BACKGROUND
We conducted a systematic review to investigate avian influenza outbreaks and to explore their distribution, upon avian influenza subtype, country, avian species and other relating details as no comprehensive epidemiological analysis of global avian influenza outbreaks from 2010 to 2016 exists.
METHODS
Data was collated from four databases (Scopus, Web of Science Core Correlation, PubMed and SpringerLink electronic journal) and a global electronic reporting system (ProMED mail), using PRISMA and ORION systematic approaches. One hundred seventy three avian influenza virus outbreaks were identified and included in this review, alongside 198 ProMED mail reports.
RESULTS
Our research identified that the majority of the reported outbreaks occurred in 2016 (22.2%). These outbreaks were located in China (13.6%) and referred to commercial poultry farms (56.1%). The most common subtype reported in these outbreaks was H5N1 (38.2%), while almost 82.5% of the subtypes were highly pathogenic avian influenza viruses. There were differences noticed between ProMED mail and the scientific literature screened.
CONCLUSIONS
Avian influenza virus has been proved to be able to contaminate all types of avian species, including commercial poultry farms, wild birds, backyard domestic animals, live poultry, game birds and mixed poultry. The study focused on wet markets, slaughterhouses, wild habitats, zoos and natural parks, in both developed and developing countries. The impact of avian influenza virus seems disproportionate and could potentially burden the already existing disparities in the public health domain. Therefore, a collaboration between all the involved health sectors is considered to be more than necessary.
Topics: Animals; China; Disease Outbreaks; Global Health; Humans; Influenza A Virus, H5N1 Subtype; Influenza in Birds; Poultry; Poultry Diseases
PubMed: 29368637
DOI: 10.1186/s13643-018-0691-z -
Vaccine Sep 2017Indonesia has implemented multiple strategies to control Highly Pathogenic Avian Influenza H5N1 (HPAI/H5N1), including the licensure and use of multiple vaccine... (Meta-Analysis)
Meta-Analysis Review
Indonesia has implemented multiple strategies to control Highly Pathogenic Avian Influenza H5N1 (HPAI/H5N1), including the licensure and use of multiple vaccine formulations. The continuous drift of Indonesian HPAI/H5N1 viruses and emergence of a new clade in 2012 that became dominant in 2016, demands the assessment of commercial vaccine formulations against Indonesian field viruses. Seven databases were explored to identify relevant literature reporting performance of commercial vaccines against Indonesian HPAI/H5N1 viruses. After methodological assessment, data were collated and analyzed to report immunogenicity and vaccine efficacy (VE) to prevent respiratory and cloacal viral shedding 2-day post challenge, and death at the end of the follow-up period. Meta-analyses were performed to assess VE consistency of alternative formulations and to explore sources of heterogeneity in VE. In total, 65 studies and 46 vaccine formulations from 13 articles were grouped per OIE's VE protocols (group 1) and variations of it (groups 2,3,4). We found that concurrence of vaccine-seed and challenge-viruses in a clade designation might be a better proxy of VE than current estimates based on vaccine-homologous HI antibody titers, particularly against current fourth order clade viruses (groups 1&2). Prime-boosting was efficacious across different chicken breeds (group 3), and early vaccination may increase the risk of death (group 4). One Indonesian vaccine was tested against the new dominant clade, conferring consistent protection in chickens but not in ducks. Meta-analyses revealed high inconsistency (I≥75%) and inefficacy of LPAI formulations against current field viruses, while potential sources of inconsistent VE were formulation of seed-homologous vaccines and the species vaccinated. We conclude that the VE of commercial vaccines in Indonesia changes as Indonesian HPAI/H5N1 evolve into new clades, which should warrant continuous matching between vaccine-seeds and emerging HPAI/H5N1. Furthermore, given the characteristics of the new Indonesian dominant HPAI/H5N1 clade, further studies to confirm VE across species are warranted.
Topics: Animals; Chickens; Ducks; Indonesia; Influenza A Virus, H5N1 Subtype; Influenza Vaccines; Influenza in Birds
PubMed: 28780119
DOI: 10.1016/j.vaccine.2017.07.059 -
The American Journal of Tropical... Aug 2017Almost all human infections by avian influenza viruses (AIVs) are transmitted from poultry. A systematic review was conducted to identify practices associated with human... (Meta-Analysis)
Meta-Analysis Review
Almost all human infections by avian influenza viruses (AIVs) are transmitted from poultry. A systematic review was conducted to identify practices associated with human infections, their prevalence, and rationale. Observational studies were identified through database searches. Meta-analysis produced combined odds ratio estimates. The prevalence of practices and rationales for their adoptions were reported. Of the 48,217 records initially identified, 65 articles were included. Direct and indirect exposures to poultry were associated with infection for all investigated viral subtypes and settings. For the most frequently reported practices, association with infection seemed stronger in markets than households, for sick and dead than healthy poultry, and for H7N9 than H5N1. Practices were often described in general terms and their frequency and intensity of contact were not provided. The prevalence of practices was highly variable across studies, and no studies comprehensively explored reasons behind the adoption of practices. Combining epidemiological and targeted anthropological studies would increase the spectrum and detail of practices that could be investigated and should aim to provide insights into the rationale(s) for their existence. A better understanding of these rationales may help to design more realistic and acceptable preventive public health measures and messages.
Topics: Animals; Humans; Influenza in Birds; Influenza, Human; Poultry; Prevalence; Zoonoses
PubMed: 28749769
DOI: 10.4269/ajtmh.17-0014 -
PloS One 2017Avian influenza or bird flu is a highly contagious acute viral disease that can occur in epidemics and cross-border forms in poultry and wild birds. The characteristics... (Review)
Review
Avian influenza or bird flu is a highly contagious acute viral disease that can occur in epidemics and cross-border forms in poultry and wild birds. The characteristics of avian influenza viruses (AIVs) allow the emergence of new viral variants, some with zoonotic and pandemic potential. AIVs have been identified in Latin America; however, there is a lack of understanding of these viruses at the regional level. We performed a systematic literature review on serological or molecular evidence of AIVs circulation in Latin America. Methods were designed based on the PRISMA and STROME guidelines. Only peer-reviewed studies published between 2000 to 2015 and data was analysed based on country, viral subtype, avian species, and phylogenetic origins. From 271 studies initially found only twenty-six met our inclusion criteria. Evidence of AIVs infection was found in most Latin American countries, with Mexico as the country with the largest number of conducted studies and reported cases during the period analysed, followed by Chile and Argentina. Most of the AIVs were early reported through surveillance systems and at least 14 different subtypes of influenza viruses were reported in birds, and the presence of both low (92.9%) and high (7.1%) pathogenic AIVs was shown in Latin America. Of the reported AIVs in Latin America, 43.7% belong to migratory birds, 28.1% to local wild birds, and 28.1% to poultry. The migratory bird population mainly comprises families belonging to the orders Anseriformes and Charadriformes. We highlight the importance of epidemiological surveillance systems and the possible role of different migratory birds in the transmission of AIVs within the Americas. Our findings demonstrate the limited information on AIVs in Latin America and highlight the need of more studies on AIVs at the regional level, particularly those focused on identifying the endemic subtypes in regional wild birds.
Topics: Animal Migration; Animals; Animals, Wild; Genotype; Influenza A virus; Influenza in Birds; Latin America; Poultry
PubMed: 28632771
DOI: 10.1371/journal.pone.0179573 -
PloS One 2017The emergence of the 2009 influenza pandemic virus with a swine origin stressed the importance of improving influenza surveillance in swine populations. The objectives... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
The emergence of the 2009 influenza pandemic virus with a swine origin stressed the importance of improving influenza surveillance in swine populations. The objectives of this systematic review and meta-analysis were to describe epidemiological features of swine influenza (SI) across the world and identify factors impacting swine influenza virus surveillance.
METHODS
The systematic review followed the PRISMA guidelines. Articles published after 1990 containing data on SI on pig and herd-level seroprevalence, isolation and detection rates, and risk factors were included. Meta-regression analyses using seroprevalence and virological rates were performed.
RESULTS
A total of 217 articles were included. Low avian influenza (AI) seroprevalence (means pig = 4.1%; herd = 15%) was found, showing that AIV do not readily establish themselves in swine while SIV seroprevalence was usually high across continents (influenza A means pig = 32.6-87.8%; herd = 29.3-100%). Higher pig density and number of pigs per farm were shown by the meta-regression analyses and/or the risk factor articles to be associated with higher SI seroprevalence. Lower seroprevalence levels were observed for countries with low-to-medium GDP. These results suggest that larger industrial farms could be more at risk of SIV circulation. Sampling swine with influenza-like illness (ILI) was positively associated with higher isolation rates; most studies in Europe, Latin and North America were targeting swine with ILI.
CONCLUSIONS
To improve understanding of SI epidemiology, standardization of the design and reporting of SI epidemiological studies is desirable. Performance of SI surveillance systems in low-to-medium GDP countries should be evaluated to rule out technical issues linked to lower observed SIV prevalence. Targeting certain swine age groups, farming systems and swine with ILI may improve the surveillance cost-effectiveness. However, focusing on pigs with ILI may bias virus detection against strains less virulent for swine but which may be important as pandemic threats.
Topics: Animals; Europe; Humans; Influenza A Virus, H1N1 Subtype; Influenza, Human; North America; Orthomyxoviridae Infections; Seroepidemiologic Studies; Swine; Swine Diseases; Zoonoses
PubMed: 28591202
DOI: 10.1371/journal.pone.0179044 -
Vaccine May 2017Cross-clade immunogenic stockpiled H5N1 vaccines may decrease the morbidity and transmission of infection during the initial phase of influenza pandemic. Meta-analysis... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Cross-clade immunogenic stockpiled H5N1 vaccines may decrease the morbidity and transmission of infection during the initial phase of influenza pandemic. Meta-analysis of cross-reactive antibodies induced by oil-in-water emulsion adjuvanted (OWEA) influenza H5N1 virus monovalent vaccines with circulating heterologous H5N1 virus strains, isolated from human infections was performed.
METHODS
Literature search of MEDLINE, EMBASE, Web of Knowledge, The Cochrane Library, ClinicalTrials.gov, and International Standard Randomised Controlled Trial Number registry was conducted up through December 1, 2015. Methodologically qualified studies were included for (1) use of two doses of licensed OWEA (AS03 or MF59) egg-derived, inactivated influenza H5N1 virus monovalent vaccine, (2) participant age between 18 and 64years, and (3) evaluation of immunogenicity outcome for one or more subclade. Meta-analysis assessed the cross-reactivity of antibodies elicited by clade 1 adjuvanted vaccine strain against clade 2.1 virus strain (A/Vietnam/1194/2004 vs. A/Indonesia/05/2005); and separately against clade 2.2 virus strain (A/Vietnam/1194/2004 vs. A/turkey/Turkey/1/05); and clade 2.1 adjuvanted vaccine strain against clade 1 virus strain (A/Indonesia/05/2005 vs. A/Vietnam/1194/2004). Quantitative publication bias and influence analysis was conducted to evaluate potential impact of unpublished or new studies on the robustness of meta-analysis.
RESULTS
Of 960 articles, 53 qualified for quality assessment and 15 studies met the inclusion criteria. All assessed clade pairs elicited cross-reactive antibodies (clade 1 against clade 2.1 and 2.2; clade 2.1 against clade 1, 2.2, and 2.3). Heterologous strains of same sub-clade are likely to elicit higher cross-reactive antibodies.
CONCLUSIONS
OWEA influenza H5N1 virus monovalent vaccines exhibit broad cross-clade immunogenicity, a desired feature for vaccine stockpiling not yet demonstrated by unadjuvanted vaccines. In case of an impending H5N1 virus pandemic, stockpiled OWEA influenza H5N1 virus monovalent vaccines may allow population priming that could slow down the course of pandemic and could offer additional time needed for development of an effective strain specific vaccine supply.
Topics: Adjuvants, Immunologic; Adolescent; Adult; Antibodies, Viral; Cross Reactions; Emulsions; Female; Hemagglutination Inhibition Tests; Humans; Immunogenicity, Vaccine; Influenza A Virus, H5N1 Subtype; Influenza Vaccines; Influenza, Human; Male; Middle Aged; Oils; Pandemics; Water; Young Adult
PubMed: 28483200
DOI: 10.1016/j.vaccine.2017.04.029 -
Transboundary and Emerging Diseases Dec 2016The aim of this work was to explore the comparative epidemiology of influenza viruses, H5N1 and H7N9, in both bird and human populations. Specifically, the article... (Review)
Review
The aim of this work was to explore the comparative epidemiology of influenza viruses, H5N1 and H7N9, in both bird and human populations. Specifically, the article examines similarities and differences between the two viruses in their genetic characteristics, distribution patterns in human and bird populations and postulated mechanisms of global spread. In summary, H5N1 is pathogenic in birds, while H7N9 is not. Yet both have caused sporadic human cases, without evidence of sustained, human-to-human spread. The number of H7N9 human cases in the first year following its emergence far exceeded that of H5N1 over the same time frame. Despite the higher incidence of H7N9, the spatial distribution of H5N1 within a comparable time frame is considerably greater than that of H7N9, both within China and globally. The pattern of spread of H5N1 in humans and birds around the world is consistent with spread through wild bird migration and poultry trade activities. In contrast, human cases of H7N9 and isolations of H7N9 in birds and the environment have largely occurred in a number of contiguous provinces in south-eastern China. Although rates of contact with birds appear to be similar in H5N1 and H7N9 cases, there is a predominance of incidental contact reported for H7N9 as opposed to close, high-risk contact for H5N1. Despite the high number of human cases of H7N9 and the assumed transmission being from birds, the corresponding level of H7N9 virus in birds in surveillance studies has been low, particularly in poultry farms. H7N9 viruses are also diversifying at a much greater rate than H5N1 viruses. Analyses of certain H7N9 strains demonstrate similarities with engineered transmissible H5N1 viruses which make it more adaptable to the human respiratory tract. These differences in the human and bird epidemiology of H5N1 and H7N9 raise unanswered questions as to how H7N9 has spread, which should be investigated further.
Topics: Animals; Animals, Wild; Birds; China; Humans; Incidence; Influenza A Virus, H5N1 Subtype; Influenza A Virus, H7N9 Subtype; Influenza in Birds; Influenza, Human; Poultry
PubMed: 25644240
DOI: 10.1111/tbed.12327 -
PloS One 2016Avian influenza viruses are able to persist in the environment, in-between the transmission of the virus among its natural hosts. Quantifying the environmental factors... (Meta-Analysis)
Meta-Analysis Review
Avian influenza viruses are able to persist in the environment, in-between the transmission of the virus among its natural hosts. Quantifying the environmental factors that affect the persistence of avian influenza virus is important for influencing our ability to predict future outbreaks and target surveillance and control methods. We conducted a systematic review and quantitative meta-analysis of the environmental factors that affect the decay of low pathogenic avian influenza virus (LPAIV) in water. Abiotic factors affecting the persistence of LPAIV have been investigated for nearly 40 years, yet published data was produced by only 26 quantitative studies. These studies have been conducted by a small number of principal authors (n = 17) and have investigated a narrow range of environmental conditions, all of which were based in laboratories with limited reflection of natural conditions. The use of quantitative meta-analytic techniques provided the opportunity to assess persistence across a greater range of conditions than each individual study can achieve, through the estimation of mean effect-sizes and relationships among multiple variables. Temperature was the most influential variable, for both the strength and magnitude of the effect-size. Moderator variables explained a large proportion of the heterogeneity among effect-sizes. Salinity and pH were important factors, although future work is required to broaden the range of abiotic factors examined, as well as including further diurnal variation and greater environmental realism generally. We were unable to extract a quantitative effect-size estimate for approximately half (50.4%) of the reported experimental outcomes and we strongly recommend a minimum set of quantitative reporting to be included in all studies, which will allow robust assimilation and analysis of future findings. In addition we suggest possible means of increasing the applicability of future studies to the natural environment, and evaluating the biological content of natural waterbodies.
Topics: Animals; Birds; Disease Outbreaks; Influenza A virus; Influenza in Birds; Salinity; Temperature; Water Microbiology
PubMed: 27736884
DOI: 10.1371/journal.pone.0161929 -
Avian Diseases Sep 2016Emerging and re-emerging diseases are continuously diagnosed in poultry species. A few of these diseases are known to cross the species barrier, thus posing a public... (Review)
Review
Emerging and re-emerging diseases are continuously diagnosed in poultry species. A few of these diseases are known to cross the species barrier, thus posing a public health risk and an economic burden. We identified and synthesized global evidence for poultry nonfoodborne zoonoses to better understand these diseases in people who were exposed to different poultry-related characteristics (e.g., occupational or nonoccupational, operational types, poultry species, outbreak conditions, health status of flocks). This review builds on current knowledge on poultry zoonoses/potentially zoonotic agents transmitted via the nonfoodborne route. It also identifies research gaps and potential intervention points within the poultry industry to reduce zoonotic transmission by using various knowledge synthesis tools such as systematic review (SR) and qualitative (descriptive) and quantitative synthesis methods (i.e., meta-analysis). Overall, 1663 abstracts were screened and 156 relevant articles were selected for further review. Full articles (in English) were retrieved and critically appraised using routine SR methods. In total, eight known zoonotic diseases were reviewed: avian influenza (AI) virus (n = 85 articles), Newcastle disease virus (n = 8), West Nile virus (WNV, n = 2), avian Chlamydia (n = 24), Erysipelothrix rhusiopathiae (n = 3), methicillin-resistant Staphylococcus aureus (MRSA, n = 15), Ornithonyssus sylvarium (n = 4), and Microsporum gallinae (n = 3). In addition, articles on other viral poultry pathogens (n = 5) and poultry respiratory allergens derived from mites and fungi (n = 7) were reviewed. The level of investigations (e.g., exposure history, risk factor, clinical disease in epidemiologically linked poultry, molecular studies) to establish zoonotic linkages varied across disease agents and across studies. Based on the multiple outcome measures captured in this review, AI virus seems to be the poultry zoonotic pathogen that may have considerable and significant public health consequences; however, epidemiologic reports have only documented severe human cases clustered in Asia and not in North America. In contrast, avian Chlamydia and MRSA reports clustered mainly in Europe and less so in North America and other regions. Knowledge gaps in other zoonoses or other agents were identified, including potential direct (i.e., nonmosquito-borne) transmission of WNV from flocks to poultry workers, the public health and clinical significance of poultry-derived (livestock-associated) MRSA, the zoonotic significance of other viruses, and the role of poultry allergens in the pathophysiology of respiratory diseases of poultry workers. Across all pathogens reviewed, the use of personal protective equipment was commonly cited as the most important preventive measure to reduce the zoonotic spread of these diseases and the use of biosecurity measures to reduce horizontal transmission in flock populations. The studies also emphasized the need for flock monitoring and an integrated approach to prevention (i.e., veterinary-public health coordination with regard to diagnosis, and knowledge translation and education in the general population) to reduce zoonotic transmission.
Topics: Animals; Humans; Poultry; Poultry Diseases; Zoonoses
PubMed: 27610715
DOI: 10.1637/11413-032416-Review.1