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One Health (Amsterdam, Netherlands) Dec 2016Live poultry markets (LPMs) pose a threat to public health by promoting the amplification and dissemination of avian influenza viruses (AIVs) and by providing the ideal...
BACKGROUND
Live poultry markets (LPMs) pose a threat to public health by promoting the amplification and dissemination of avian influenza viruses (AIVs) and by providing the ideal setting for zoonotic influenza transmission.
OBJECTIVE
This review assessed the impact of different interventions implemented in LPMs to control the emergence of zoonotic influenza.
METHODS
Publications were identified through a systematic literature search in the PubMed, MEDLINE and Web of Science databases. Eligible studies assessed the impact of different interventions, such as temporary market closure or a ban on holding poultry overnight, in reducing i) AIV-detection rates in birds and the market environment or ii) influenza incidence in humans. Unpublished literature, reviews, editorials, cross-sectional studies, theoretical models and publications in languages other than English were excluded. Relevant findings were extracted and critically evaluated. For the comparative analysis of findings across studies, standardized outcome measures were computed as i) the relative risk reduction (RRR) of AIV-detection in LPMs and ii) incidence rate ratios (IRRs) of H7N9-incidence in humans.
RESULTS
A total of 16 publications were identified and reviewed. Collectively, the data suggest that AIV-circulation can be significantly reduced in the LPM-environment and among market-birds through (i) temporary LPM closure, (ii) periodic rest days (iii) market depopulation overnight and (iv) improved hygiene and disinfection. Overall, the findings indicate that the length of stay of poultry in the market is a critical control point to interrupt the AIV-replication cycle within LPMs. In addition, temporary LPM closure was associated with a significant reduction of the incidence of zoonotic influenza. The interpretation of these findings is limited by variations in the implementation of interventions. In addition, some of the included studies were of ecologic nature or lacked an inferential framework, which might have lead to cosiderable confounding and bias.
CONCLUSIONS
The evidence collected in this review endorses permanent LPM-closure as a long-term objective to reduce the zoonotic risk of avian influenza, although its economic and socio-political implications favour less drastic interventions, e.g. weekly rest days, for implementation in the short-term.
PubMed: 27213177
DOI: 10.1016/j.onehlt.2016.03.002 -
The Lancet. Infectious Diseases Jul 2016Avian influenza A H5N1 viruses have caused many, typically severe, human infections since the first human case was reported in 1997. However, no comprehensive... (Review)
Review
Avian influenza A H5N1 viruses have caused many, typically severe, human infections since the first human case was reported in 1997. However, no comprehensive epidemiological analysis of global human cases of H5N1 from 1997 to 2015 exists. Moreover, few studies have examined in detail the changing epidemiology of human H5N1 cases in Egypt, especially given the outbreaks since November, 2014, which have the highest number of cases ever reported worldwide in a similar period. Data on individual patients were collated from different sources using a systematic approach to describe the global epidemiology of 907 human H5N1 cases between May, 1997, and April, 2015. The number of affected countries rose between 2003 and 2008, with expansion from east and southeast Asia, then to west Asia and Africa. Most cases (67·2%) occurred from December to March, and the overall case-fatality risk was 483 (53·5%) of 903 cases which varied across geographical regions. Although the incidence in Egypt has increased dramatically since November, 2014, compared with the cases beforehand, there were no significant differences in the fatality risk, history of exposure to poultry, history of patient contact, and time from onset to hospital admission in the recent cases.
Topics: Animals; Disease Outbreaks; Global Health; Humans; Incidence; Influenza A Virus, H5N1 Subtype; Influenza in Birds; Influenza, Human; Poultry
PubMed: 27211899
DOI: 10.1016/S1473-3099(16)00153-5 -
PloS One 2016Understanding the evolutionary dynamics of influenza viruses is essential to control both avian and human influenza. Here, we analyze host-specific and segment-specific... (Review)
Review
Understanding the evolutionary dynamics of influenza viruses is essential to control both avian and human influenza. Here, we analyze host-specific and segment-specific Tajima's D trends of influenza A virus through a systematic review using viral sequences registered in the National Center for Biotechnology Information. To avoid bias from viral population subdivision, viral sequences were stratified according to their sampling locations and sampling years. As a result, we obtained a total of 580 datasets each of which consists of nucleotide sequences of influenza A viruses isolated from a single population of hosts at a single sampling site within a single year. By analyzing nucleotide sequences in the datasets, we found that Tajima's D values of viral sequences were different depending on hosts and gene segments. Tajima's D values of viruses isolated from chicken and human samples showed negative, suggesting purifying selection or a rapid population growth of the viruses. The negative Tajima's D values in rapidly growing viral population were also observed in computer simulations. Tajima's D values of PB2, PB1, PA, NP, and M genes of the viruses circulating in wild mallards were close to zero, suggesting that these genes have undergone neutral selection in constant-sized population. On the other hand, Tajima's D values of HA and NA genes of these viruses were positive, indicating HA and NA have undergone balancing selection in wild mallards. Taken together, these results indicated the existence of unknown factors that maintain viral subtypes in wild mallards.
Topics: Algorithms; Animals; Birds; Computational Biology; Computer Simulation; Disease Outbreaks; Evolution, Molecular; Genes, Viral; Host-Pathogen Interactions; Humans; Influenza A virus; Influenza in Birds; Influenza, Human; Models, Statistical; Mutation
PubMed: 26760775
DOI: 10.1371/journal.pone.0147021 -
BMC Infectious Diseases Jan 2016Most previous evolutionary studies of influenza A have focussed on genetic drift, or reassortment of specific gene segments, hosts or subtypes. We conducted a systematic... (Review)
Review
BACKGROUND
Most previous evolutionary studies of influenza A have focussed on genetic drift, or reassortment of specific gene segments, hosts or subtypes. We conducted a systematic literature review to identify reported claimed reassortant influenza A lineages with genomic data available in GenBank, to obtain 646 unique first-report isolates out of a possible 20,781 open-access genomes.
RESULTS
After adjusting for correlations, only: swine as host, China, Europe, Japan and years between 1997 and 2002; remained as significant risk factors for the reporting of reassortant viral lineages. For swine H1, more reassortants were observed in the North American H1 clade compared with the Eurasian avian-like H1N1 clade. Conversely, for avian H5 isolates, a higher number of reported reassortants were observed in the European H5N2/H3N2 clade compared with the H5N2 North American clade.
CONCLUSIONS
Despite unavoidable biases (publication, database choice and upload propensity) these results synthesize a large majority of the current literature on novel reported influenza A reassortants and are a potentially useful prerequisite to inform further algorithmic studies.
Topics: Animals; Genetic Drift; Humans; Influenza A Virus, H1N1 Subtype; Influenza A Virus, H3N2 Subtype; Influenza A Virus, H5N2 Subtype; Influenza, Human; Phylogeny; Reassortant Viruses
PubMed: 26732146
DOI: 10.1186/s12879-015-1298-9 -
Clinical Microbiology and Infection :... Oct 2015Administration of corticosteroids to patients affected by influenza virus, especially pandemic avian influenza virus, although relatively common, remains controversial.... (Meta-Analysis)
Meta-Analysis Review
Administration of corticosteroids to patients affected by influenza virus, especially pandemic avian influenza virus, although relatively common, remains controversial. A systematic review and meta-analysis was performed to assess the impact of corticosteroid treatment on outcomes of patients with influenza virus infection. The PubMed, EMBASE, Web of Science and Cochrane Library databases were searched up to February, 2015. Studies comparing corticosteroid treatment with no corticosteroid treatment in patients with influenza virus infection were included. The primary outcomes assessed were the association of mortality and nosocomial infection with corticosteroid treatment. Two authors independently extracted the data. ORs and weighted mean differences (WMDs) were used to describe dichotomous data and continuous data, respectively. Nineteen studies with 4916 patients were included in this meta-analysis. The results showed that corticosteroid treatment was significantly associated with mortality (OR 1.98, 95% CI 1.62-2.43, p < 0.00001) and nosocomial infection (OR 3.16, 95% CI 2.09-4.78, p < 0.00001). The durations of mechanical ventilation (WMD 3.82, 95% CI 1.49-6.15, p 0.001) and intensive-care unit stay (WMD 4.78, 95% CI 2.27-7.29, p 0.0002) were both markedly longer in the corticosteroid treatment group than in the control group. These findings suggest that routine steroid use may not be ideal for influenza virus infection. However, these results are derived from observational studies, with some important biases. They should be examined in future sufficiently powered randomized trials.
Topics: Adrenal Cortex Hormones; Anti-Inflammatory Agents; Cross Infection; Humans; Influenza, Human; Length of Stay; Respiration, Artificial; Survival Analysis; Treatment Outcome
PubMed: 26123860
DOI: 10.1016/j.cmi.2015.06.022 -
The Journal of Infectious Diseases Aug 2015Given that influenza A(H9N2) is recognized as a pandemic threat, we evaluated the overall burden of influenza A(H9N2) infections among avian-exposed human populations. (Meta-Analysis)
Meta-Analysis Review
INTRODUCTION
Given that influenza A(H9N2) is recognized as a pandemic threat, we evaluated the overall burden of influenza A(H9N2) infections among avian-exposed human populations.
METHODS
We performed a systematic search of PubMed, AGRICOLA, and CAB Abstracts databases for literature published during 1997-2013. Studies reporting serological evidence of human influenza A(H9N2) infection among avian-exposed populations were included. We used a World Health Organization (WHO)-recommended case definition for serological evidence of infection based on results of hemagglutination inhibition (HI) and microneutralization (MN) assays. We calculated overall seroprevalence through a random effects meta-analysis model.
RESULTS
Seroprevalence data reported by the studies ranged from 1% to 43% (median, 9%) by HI, which was not significantly different from the seroprevalence estimated through the WHO-recommended case definition (median, 1.3%; range, 0.5%-42.6%). Reported seroprevalence by MN ranged from 0.6% to 9% (median, 2.7%), which was greater than the seroprevalence estimated through the WHO-recommended case definition (median, 0.3%; range, 0.1%-1.4%).
CONCLUSIONS
A small proportion of avian-exposed humans had evidence of influenza A(H9N2) infection. As the virus has a near global distribution in poultry, it seems likely that present surveillance efforts are missing mild or asymptomatic infections among avian-exposed persons. It seems prudent to closely monitor avian-exposed populations for influenza A(H9N2) infection to provide prepandemic warnings.
Topics: Animals; Antibodies, Viral; Humans; Influenza A Virus, H9N2 Subtype; Influenza, Human; Seroepidemiologic Studies; Zoonoses
PubMed: 25712969
DOI: 10.1093/infdis/jiv109 -
Preventive Veterinary Medicine Nov 2014Avian influenza is a severe threat both to humans and poultry, but so far, no systematic review on the identification and evaluation of the risk factors of avian... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Avian influenza is a severe threat both to humans and poultry, but so far, no systematic review on the identification and evaluation of the risk factors of avian influenza infection has been published. The objective of this meta-analysis is to provide evidence for decision-making and further research on AI prevention through identifying the risk factors associated with AI infection on poultry farms.
METHODS
The results from 15 selected studies on risk factors for AI infections on poultry farms were analyzed quantitatively by meta-analysis.
RESULTS
Open water source (OR=2.89), infections on nearby farms (OR=4.54), other livestock (OR=1.90) and disinfection of farm (OR=0.54) have significant association with AI infection on poultry farms. The subgroup analysis results indicate that there exist different risk factors for AI infections in different types of farms.
CONCLUSIONS
The main risk factors for AI infection in poultry farms are environmental conditions (open water source, infections on nearby farms), keeping other livestock on the same farm and no disinfection of the farm.
Topics: Animals; Influenza in Birds; Odds Ratio; Poultry; Risk Factors
PubMed: 25064365
DOI: 10.1016/j.prevetmed.2014.06.008 -
PloS One 2014Little is known about risk factors for severe outcomes in patients infected with H5N1 and no systematic review has been conducted. Understanding risk factors is an... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Little is known about risk factors for severe outcomes in patients infected with H5N1 and no systematic review has been conducted. Understanding risk factors is an important step for prioritizing prophylaxis or treatment in the event of a pandemic.
OBJECTIVES
To systematically evaluate risk factors for severe outcomes in patients with avian influenza H5N1 infection.
DATA SOURCES
MEDLINE, EMBASE, CINAHL, GlobalHealth, and CENTRAL through March 2011.
ELIGIBILITY CRITERIA FOR SELECTING STUDIES
Observational studies of any design published in English, French, Spanish, German or Korean that reported on risk factor-outcome combinations of interest in participants with confirmed H5N1 infections. Outcomes considered included death, ventilator support, hospital and ICU admission, pneumonia, and composite outcomes.
STUDY APPRAISAL
Risk of bias was assessed using the Newcastle-Ottawa scale (NOS).
RESULTS
We identified 20 studies reporting on 999 patients infected with H5N1. The majority of studies (n = 14, 70%) were at intermediate risk of bias, i.e. 4-6 points on the NOS. Females were at increased risk of death (OR 1.75, 95% CI 1.27-2.44), while young age, in particular <5 years of age (OR 0.44, 95% CI 0.25-0.79 for death), was protective. Data on traditional risk factors was scarce and requires further studies. Another major limitation in the published literature was lack of adjustment for confounders.
INTERPRETATION
Females were at increased risk for complications following H5N1 infection while young age protected against severe outcomes. Research on traditional risk factors was limited and is required.
Topics: Animals; Birds; Female; Host-Pathogen Interactions; Humans; Influenza A Virus, H5N1 Subtype; Influenza in Birds; Influenza, Human; Risk Factors; Sex Factors
PubMed: 24603885
DOI: 10.1371/journal.pone.0089697 -
Influenza and Other Respiratory Viruses Sep 2013Highly pathogenic avian influenza A H5N1 viruses remain a significant health threat to humans given the continued rare occurrence of human cases with a high case... (Review)
Review
Highly pathogenic avian influenza A H5N1 viruses remain a significant health threat to humans given the continued rare occurrence of human cases with a high case fatality rate. This brief literature review summarizes available evidence of risk factors for H5N1 infection in humans and updates a recent systematic review published in early 2011. Several epidemiologic studies have been published to evaluate the risk factors for H5N1 infection in humans, including contact with poultry and poultry products and non-poultry-related contact such as from H5N1-contaminated water. While most H5N1 cases are attributed to exposure to sick poultry, it is unclear how many may be due to human-to-human transmission. The collective results of published literature suggest that transmission risk of H5N1 from poultry to humans may be highest among individuals who may have been in contact with the highest potential concentrations of virus shed by poultry. This suggests that there may be a threshold of virus concentration needed for effective transmission and that circulating H5N1 strains have not yet mutated to transmit readily from either poultry to human or from human to human. However, the mode of potential transmission can be quite varied throughout different countries and by study with exposures ranging from visiting a wet market, preparing infected poultry for consumption, to swimming or bathing in ponds frequented by poultry. Several important data gaps remain in the understanding of the epidemiology of H5N1 in humans and limit our ability to interpret the results of the available H5N1 seroepidemiologic studies.
Topics: Animals; Humans; Influenza A Virus, H5N1 Subtype; Influenza in Birds; Influenza, Human; Poultry; Risk Factors; Virus Shedding; Zoonoses
PubMed: 24034480
DOI: 10.1111/irv.12077 -
Preventive Veterinary Medicine Jun 2013In the last half century, significant attention has been given to animal diseases; however, our understanding of disease processes and how to manage them at the... (Review)
Review
In the last half century, significant attention has been given to animal diseases; however, our understanding of disease processes and how to manage them at the livestock-wildlife interface remains limited. In this study, we conduct a systematic review of the scientific literature to evaluate the status of diseases at the livestock-wildlife interface in the United States. Specifically, the goals of the literature review were three fold: first to evaluate domestic animal diseases currently found in the United States where wildlife may play a role; second to identify critical issues faced in managing these diseases at the livestock-wildlife interface; and third to identify potential technical and policy strategies for addressing these issues. We found that of the 86 avian, ruminant, swine, poultry, and lagomorph diseases that are reportable to the World Organization for Animal Health (OIE), 53 are present in the United States; 42 (79%) of these have a putative wildlife component associated with the transmission, maintenance, or life cycle of the pathogen; and 21 (40%) are known to be zoonotic. At least six of these reportable diseases-bovine tuberculosis, paratuberculosis, brucellosis, avian influenza, rabies, and cattle fever tick (vector control)-have a wildlife reservoir that is a recognized impediment to eradication in domestic populations. The complex nature of these systems highlights the need to understand the role of wildlife in the epidemiology, transmission, and maintenance of infectious diseases of livestock. Successful management or eradication of these diseases will require the development of cross-discipline and institutional collaborations. Despite social and policy challenges, there remain opportunities to develop new collaborations and new technologies to mitigate the risks posed at the livestock-wildlife interface.
Topics: Animal Diseases; Animals; Animals, Domestic; Animals, Wild; Disease Reservoirs; United States
PubMed: 23254245
DOI: 10.1016/j.prevetmed.2012.11.021