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1.
Emerg Microbes Infect ; 8(1): 1370-1382, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31526249

RESUMO

Egypt is a hotspot for avian influenza virus (AIV) due to the endemicity of H5N1 and H9N2 viruses. AIVs were isolated from 329 samples collected in 2016-2018; 48% were H9N2, 37.1% were H5N8, 7.6% were H5N1, and 7.3% were co-infections with 2 of the 3 subtypes. The 32 hemagglutinin (HA) sequences of the H5N1 viruses formed a well-defined lineage within clade 2.2.1.2. The 10 HA sequences of the H5N8 viruses belonged to a subclade within 2.3.4.4. The 11 HA of H9N2 isolates showed high sequence homology with other Egyptian G1-like H9N2 viruses. The prevalence of H5N8 viruses in ducks (2.4%) was higher than in chickens (0.94%). Genetic reassortment was detected in H9N2 viruses. Antigenic analysis showed that H9N2 viruses are homogenous, antigenic drift was detected among H5N1 viruses. AI H5N8 showed higher replication rate followed by H9N2 and H5N1, respectively. H5N8 was more common in Southern Egypt, H9N2 in the Nile Delta, and H5N1 in both areas. Ducks and chickens played a significant role in transmission of H5N1 viruses. The endemicity and co-circulation of H5N1, H5N8, and H9N2 AIV coupled with the lack of a clear control strategy continues to provide avenues for further virus evolution in Egypt.


Assuntos
Coinfecção/veterinária , Monitoramento Epidemiológico/veterinária , Evolução Molecular , Virus da Influenza A Subtipo H5N1/genética , Vírus da Influenza A Subtipo H9N2/genética , Vírus Reordenados , Animais , Galinhas , Coinfecção/epidemiologia , Coinfecção/virologia , Patos , Egito/epidemiologia , Virus da Influenza A Subtipo H5N1/isolamento & purificação , Vírus da Influenza A Subtipo H9N2/isolamento & purificação , Influenza Aviária/epidemiologia , Influenza Aviária/transmissão , Doenças das Aves Domésticas/epidemiologia , Doenças das Aves Domésticas/virologia , Homologia de Sequência , Proteínas Virais/genética
2.
PLoS Comput Biol ; 15(8): e1007189, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31386651

RESUMO

Model-based phylodynamic approaches recently employed generalized linear models (GLMs) to uncover potential predictors of viral spread. Very recently some of these models have allowed both the predictors and their coefficients to be time-dependent. However, these studies mainly focused on predictors that are assumed to be constant through time. Here we inferred the phylodynamics of avian influenza A virus H9N2 isolated in 12 Asian countries and regions under both discrete trait analysis (DTA) and structured coalescent (MASCOT) approaches. Using MASCOT we applied a new time-dependent GLM to uncover the underlying factors behind H9N2 spread. We curated a rich set of time-series predictors including annual international live poultry trade and national poultry production figures. This time-dependent phylodynamic prediction model was compared to commonly employed time-independent alternatives. Additionally the time-dependent MASCOT model allowed for the estimation of viral effective sub-population sizes and their changes through time, and these effective population dynamics within each country were predicted by a GLM. International annual poultry trade is a strongly supported predictor of virus migration rates. There was also strong support for geographic proximity as a predictor of migration rate in all GLMs investigated. In time-dependent MASCOT models, national poultry production was also identified as a predictor of virus genetic diversity through time and this signal was obvious in mainland China. Our application of a recently introduced time-dependent GLM predictors integrated rich time-series data in Bayesian phylodynamic prediction. We demonstrated the contribution of poultry trade and geographic proximity (potentially unheralded wild bird movements) to avian influenza spread in Asia. To gain a better understanding of the drivers of H9N2 spread, we suggest increased surveillance of the H9N2 virus in countries that are currently under-sampled as well as in wild bird populations in the most affected countries.


Assuntos
Vírus da Influenza A Subtipo H9N2 , Influenza Aviária/transmissão , Modelos Biológicos , Migração Animal , Animais , Animais Selvagens/virologia , Ásia/epidemiologia , Teorema de Bayes , Aves/virologia , Comércio , Biologia Computacional , Monitoramento Ambiental , Vírus da Influenza A Subtipo H9N2/classificação , Vírus da Influenza A Subtipo H9N2/genética , Influenza Aviária/epidemiologia , Influenza Aviária/virologia , Modelos Lineares , Filogeografia/estatística & dados numéricos , Dinâmica Populacional , Aves Domésticas/virologia , Análise Espaço-Temporal
3.
Transbound Emerg Dis ; 66(6): 2537-2545, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31376332

RESUMO

Influenza A viruses are one of the most significant viral groups globally with substantial impacts on human, domestic animal and wildlife health. Wild birds are the natural reservoirs for these viruses, and active surveillance within wild bird populations provides critical information about viral evolution forming the basis of risk assessments and countermeasure development. Unfortunately, active surveillance programs are often resource-intensive, and thus, enhancing programs for increased efficiency is paramount. Machine learning, a branch of artificial intelligence applications, provides statistical learning procedures that can be used to gain novel insights into disease surveillance systems. We use a form of machine learning, gradient boosted trees, to estimate the probability of isolating avian influenza viruses (AIV) from wild bird samples collected during surveillance for AIVs from 2006 to 2011 in the United States. We examined several predictive features including age, sex, bird type, geographic location and matrix gene rRT-PCR results. Our final model had high predictive power and only included geographic location and rRT-PCR results as important predictors. The highest predicted viral isolation probability was for samples collected from the north-central states and the south-eastern region of Alaska. Lower rRT-PCR Ct-values are associated with increased likelihood of AIV isolation, and the model estimated 16% probability of isolating AIV from samples declared negative (i.e., ≥35 Ct-value) using the rRT-PCR screening test and standard protocols. Our model can be used to prioritize previously collected samples for isolation and rapidly evaluate AIV surveillance designs to maximize the probability of viral isolation given limited resources and laboratory capacity.


Assuntos
Animais Selvagens/virologia , Aves/virologia , Influenza Aviária/epidemiologia , Aprendizado de Máquina , Animais , Inteligência Artificial , Reservatórios de Doenças , Influenza Aviária/transmissão , Reação em Cadeia da Polimerase/veterinária , Vigilância da População , Estados Unidos/epidemiologia
4.
Transbound Emerg Dis ; 66(6): 2411-2425, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31328387

RESUMO

Since 2014, H5 highly pathogenic avian influenza viruses (HPAIVs) from clade 2.3.4.4 have been persistently circulating in Southern China. This has caused huge losses in the poultry industry. In this study, we analysed the genetic characteristics of seven H5N6 HPAIVs of clade 2.3.4.4 that infected birds in Southern China in 2016. Phylogenetic analysis grouped the HA, PB2, PA, M and NS genes as MIX-like, and the NA genes grouped into the Eurasian lineage. The PB1 genes of the GS24, GS25, CK46 and GS74 strains belonged to the VN 2014-like group and the others were grouped as MIX-like. The NP genes of GS24 and GS25 strains belonged to the ZJ-like group, but the others were MIX-like. Thus, these viruses came from different genotypes, and the GS24, GS25, CK46 and GS74 strains displayed genotype recombination. Additionally, our results showed that the mean death time of all chickens inoculated with 105 EID50 of CK46 or GS74 viruses was 3 and 3.38 days, respectively. The viruses replicated at high titers in all tested tissues of the inoculated chickens. They also replicated in all tested tissues of naive contact chickens, but their replication titers in some tissues were significantly different (p < 0.05). Thus, the viruses displayed high pathogenicity and variable transmission in chickens. Therefore, it is necessary to focus on the pathogenic variation and molecular evolution of H5N6 HPAIVs in order to prevent and control avian influenza in China.


Assuntos
Vírus da Influenza A/genética , Vírus da Influenza A/patogenicidade , Influenza Aviária/transmissão , Animais , Galinhas/virologia , China , Evolução Molecular , Genótipo , Vírus da Influenza A/classificação , Filogenia , Recombinação Genética , Replicação Viral
5.
Vet Microbiol ; 233: 1-4, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31176393

RESUMO

Domestic ducks are considered as the interface between wild aquatic birds and terrestrial poultry and play an important role in the transmission and evolution of avian influenza viruses (AIVs). However, the infectivity of H9N2 AIVs in different domestic duck species has not been systematically evaluated. Here we investigated the infectivity of various genotypes of chicken H9N2 AIVs in Pekin duck (Anas Platyrhynchos), Mallard duck (Anas Platyrhynchos) and Muscovy duck (Cairina Moschata) through intranasal inoculation. We found that Pekin ducks and Mallard ducks were generally resistant to chicken H9N2 virus infection, while Muscovy ducks were relatively susceptible to H9N2 AIVs. All the tested viruses were isolated from oropharynx, trachea and lung tissues of Muscovy ducks. Additionally, genotype 57 (G57) H9N2 AIVs, which was predominant in chickens since 2010, showed increased virus replication in this duck species, indicating an improved interspecies transmission ability of recent H9N2 viruses from chickens to ducks. Our results demonstrated the role of Muscovy ducks in the ecology of H9N2 AIVs. More attentions should be paid to this host during viral surveillances. Additionally, inactivated H9N2 vaccine may be unnecessarily used in Pekin and Mallard ducks.


Assuntos
Patos/virologia , Influenza Aviária/transmissão , Doenças das Aves Domésticas/virologia , Replicação Viral , Animais , Galinhas/virologia , Suscetibilidade a Doenças , Vírus da Influenza A Subtipo H9N2/genética , Vírus da Influenza A Subtipo H9N2/fisiologia , Pulmão/virologia , Orofaringe/virologia , Traqueia/virologia
6.
Emerg Microbes Infect ; 8(1): 823-826, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31164049

RESUMO

The spread of highly pathogenic avian influenza (HPAI) H5N1 virus is associated with wild fowl migration in East Asian-Australasian (EA) and Central Asian (CA) flyways. However, the spread of H5N1 virus between the two flyways is still unclear. Here, the movements of wild waterfowl were obtained from satellite tracking data covering seven bar-headed geese and three great black-headed gulls breeding in the Qinghai Lake area (along the EA flyway), and 20 whooper swans wintering in the Sanmenxia Reservoir area (at the CA flyway). From the 2688 samples that were screened from wild birds at Qinghai Lake after an outbreak of H5N1 in July 2015, four genomes of H5N1 virus were obtained from bar-headed geese. The results of phylogenetic analysis indicated that these H5N1 viruses belonged to clade 2.3.2.1c and their gene fragments were highly homologous with A/whooper swan/Henan/SMX1/2015 (H5N1) virus (ranging from 99.76% to 100.00%) isolated from a dead whooper swan from the Sanmenxia Reservoir area along the EA flyway in January 2015. Furthermore, the coincidental timing of the H5N1 outbreak with spring migration, together with phylogenetic evidence, provided new evidence of the east-to-west spread of HPAI H5N1 between the EA and CA migratory flyways of China.


Assuntos
Anseriformes/fisiologia , Virus da Influenza A Subtipo H5N1/fisiologia , Influenza Aviária/epidemiologia , Migração Animal , Animais , Animais Selvagens/fisiologia , Animais Selvagens/virologia , Anseriformes/virologia , Ásia/epidemiologia , Austrália/epidemiologia , China/epidemiologia , Virus da Influenza A Subtipo H5N1/classificação , Virus da Influenza A Subtipo H5N1/genética , Virus da Influenza A Subtipo H5N1/isolamento & purificação , Influenza Aviária/transmissão , Influenza Aviária/virologia , Filogenia , Estações do Ano
7.
J Vet Sci ; 20(3): e27, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31161745

RESUMO

In 2016, novel H5N6 highly pathogenic avian influenza virus emerged in Korea. During the outbreak, the virus caused the largest culling, especially in brown chicken lines. We determined the pathogenicity and transmissibility of the virus in 2 white chicken lines of the specific pathogen-free chickens, broilers and brown chicken line of Korean native chicken (KNC). A KNC had a longer virus shedding period and longer mean death time than others. Our study showed that this characteristic in the KNC might have contributed to a farm-to-farm transmission of the brown chicken farms.


Assuntos
Vírus da Influenza A/patogenicidade , Influenza Aviária/virologia , Doenças das Aves Domésticas/virologia , Animais , Cruzamento , Galinhas/virologia , Influenza Aviária/transmissão , Doenças das Aves Domésticas/transmissão , República da Coreia , Virulência
8.
Influenza Other Respir Viruses ; 13(5): 496-503, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31187583

RESUMO

BACKGROUND: Highly pathogenic avian influenza (HPAI) A(H7N9) virus emerged and caused human infections during the 2016-2017 epidemic wave of influenza A(H7N9) viruses in China. We report a human infection with HPAI H7N9 virus and six environmental isolates in Fujian Province, China. METHODS: Environmental surveillance was conducted in live poultry markets and poultry farms in Fujian, China. Clinical and epidemiologic data and samples were collected. Real-time RT-PCRs were conducted for each sample, and H7-positive samples were isolated using embryonated chicken eggs. Full genomes of the isolates were obtained by next-generation sequencing. Phylogenetic analysis and antigenic analysis were conducted. RESULTS: A 59-year-old man who raised about 1000 ducks was identified as HPAI H7N9 infection. Six HPAI H7 viruses were isolated from environmental samples, including five H7N9 viruses and one H7N6 virus. Phylogenetic results showed the human and environmental viruses are highly genetically diverse and containing significantly different gene constellation from that of other HPAI H7N9 previously reported. The internal genes derived from H7N9/H9N2, H5N6, and the Eurasian wild-bird gene pool, indicating waterfowl-originated genotypes, have emerged in HPAI H7N9/N6 viruses and caused human infection. CONCLUSION: The new genotypes raise the concern that these HPAI H7 viruses might transmit back into migratory birds and spread to other countries as the HPAI H5Nx viruses. Considering their capability of causing severe infections in both human and poultry, the HPAI H7 viruses in this study pose a risk to public health and the poultry industry and highlight the importance of sustained surveillance of these viruses.


Assuntos
Patos/virologia , Genoma Viral , Subtipo H7N9 do Vírus da Influenza A/genética , Influenza Aviária/transmissão , Influenza Humana/epidemiologia , Animais , China/epidemiologia , Epidemias , Monitoramento Epidemiológico , Humanos , Subtipo H7N9 do Vírus da Influenza A/patogenicidade , Influenza Aviária/virologia , Masculino , Pessoa de Meia-Idade , Filogenia , Aves Domésticas/virologia , Doenças das Aves Domésticas/virologia , Saúde Pública
9.
PLoS One ; 14(5): e0216478, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31067261

RESUMO

Infectious virus-laden aerosols generated during poultry processing may mediate airborne transmissions of avian influenza at live poultry markets. To develop effective control measures to reduce aerosol dispersion, we characterised the aerosol flow pattern of the mechanical defeatherers, a major source of aerosol dispersion during poultry processing at live poultry markets in China. Mechanical defeatherers create a strong air circulation during operation with inflow and outflow velocities over 1 m/s. A partial lid was designed to suppress the outflow and reduce aerosol dispersion. Computational fluid dynamics simulations confirmed that the partial lid prototype reduced the aerosol escape rate by over 65%. To validate the effectiveness of the partial lid in reducing aerosol dispersion, a field study was conducted at a retail poultry shop in Guangzhou and the concentrations of influenza viral RNA and avian 18S rRNA dispersed in air were monitored during poultry processing, with and without the use of the partial lid. At the breathing zone of the poultry worker, the use of the partial lid effectively suppressed the upward airflow and reduced the concentration of avian 18S rRNA in the air by 57%. The economic and practical partial lid can be easily implemented to reduce generation of influenza virus-laden aerosols at live poultry markets.


Assuntos
Indústria de Processamento de Alimentos , Vírus da Influenza A , Influenza Aviária/transmissão , Influenza Humana/transmissão , Modelos Biológicos , Doenças das Aves Domésticas/transmissão , Aves Domésticas , Aerossóis , Animais , China , Humanos
10.
BMC Vet Res ; 15(1): 147, 2019 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-31088548

RESUMO

BACKGROUND: Avian influenza (AI) is an infectious viral disease that affects several species and has zoonotic potential. Due to its associated health and economic repercussions, minimizing AI outbreaks is important. However, most control measures are generic and mostly target pathways important for the conventional poultry farms producing chickens, turkeys, and eggs and may not target other pathways that may be specific to the upland game bird sector. The goal of this study is to provide evidence to support the development of novel strategies for sector-specific AI control by comparing and contrasting practices and potential pathways for spread in upland game bird farms with those for conventional poultry farms in the United States. Farm practices and processes, seasonality of activities, geographic location and inter-farm distance were analyzed across the sectors. All the identified differences were framed and discussed in the context of their associated pathways for virus introduction into the farm and subsequent between-farm spread. RESULTS: Differences stemming from production systems and seasonality, inter-farm distance and farm densities were evident and these could influence both fomite-mediated and local-area spread risks. Upland game bird farms operate under a single, independent owner rather than being contracted with or owned by a company with other farms as is the case with conventional poultry. The seasonal marketing of upland game birds, largely driven by hunting seasons, implies that movements are seasonal and customer-vendor dynamics vary between industry groups. Farm location analysis revealed that, on average, an upland game bird premises was 15.42 km away from the nearest neighboring premises with birds compared to 3.74 km for turkey premises. Compared to turkey premises, the average poultry farm density in a radius of 10 km of an upland game bird premises was less than a half, and turkey premises were 3.8 times (43.5% compared with 11.5%) more likely to fall within a control area during the 2015 Minnesota outbreak. CONCLUSIONS: We conclude that the existing differences in the seasonality of production, isolated geographic location and epidemiological seclusion of farms influence AI spread dynamics and therefore disease control measures should be informed by these and other factors to achieve success.


Assuntos
Criação de Animais Domésticos/métodos , Galliformes , Vírus da Influenza A , Influenza Aviária/epidemiologia , Animais , Surtos de Doenças , Geografia , Influenza Aviária/prevenção & controle , Influenza Aviária/transmissão , Estações do Ano , Estados Unidos
11.
Artigo em Inglês | MEDLINE | ID: mdl-31142047

RESUMO

The factors affecting the transmission and geographic translocation of avian influenza viruses (AIVs) within wild migratory bird populations remain inadequately understood. In a previous study, we found that environmental transmission had little impact on AIV translocation in a model of a single migratory bird population. In order to simulate virus transmission and translocation more realistically, here we expanded this model system to include two migratory bird flocks. We simulated AIV transmission and translocation while varying four core properties: 1) Contact transmission rate; 2) infection recovery rate; 3) infection-induced mortality rate; and 4) migration recovery rate; and three environmental transmission properties: 1) Virion persistence; 2) exposure rate; and 3) re-scaled environmental infectiousness; as well as the time lag in the migration schedule of the two flocks. We found that environmental exposure rate had a significant impact on virus translocation in the two-flock model. Further, certain epidemiological features (i.e., low infection recovery rate, low mortality rate, and high migration transmission rate) in both flocks strongly affected the likelihood of virus translocation. Our results further identified the pathobiological features supporting AIV intercontinental dissemination risk.


Assuntos
Aves/virologia , Vírus da Influenza A/patogenicidade , Influenza Aviária/transmissão , Migração Animal , Animais , Animais Selvagens , Influenza Aviária/virologia
12.
Virology ; 533: 1-11, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31071540

RESUMO

An H5N6 highly pathogenic avian influenza virus (HPAIV) outbreak occurred in poultry in Japan during January 2018, and H5N6 HPAIVs killed several wild birds in 3 prefectures during Winter 2017-2018. Time-measured phylogenetic analyses demonstrated that the Hemagglutinin (HA) and internal genes of these isolates were genetically similar to clade 2.3.4.4.B H5N8 HPAIVs in Europe during Winter 2016-2017, and Neuraminidase (NA) genes of the poultry and wild bird isolates were gained through distinct reassortments with AIVs that were estimated to have circulated possibly in Siberia during Summer 2017 and Summer 2016, respectively. Lethal infectious dose to chickens was similar between the poultry and wild-bird isolates. H5N6 HPAIVs during Winter 2017-2018 in Japan had higher 50% chicken lethal doses and lower transmission efficiency than the H5Nx HPAIVs that caused previous outbreaks in Japan, thus explaining in part why cases during the 2017-2018 outbreak were sporadic.


Assuntos
Animais Selvagens/virologia , Aves/virologia , Vírus da Influenza A/isolamento & purificação , Influenza Aviária/virologia , Doenças das Aves Domésticas/virologia , Adesinas de Escherichia coli/genética , Animais , Galinhas , Vírus da Influenza A/classificação , Vírus da Influenza A/genética , Influenza Aviária/epidemiologia , Influenza Aviária/transmissão , Japão/epidemiologia , Filogenia
13.
PLoS One ; 14(5): e0216984, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31125350

RESUMO

In the re-emergence of Highly Pathogenic Avian Influenza (HPAI), live bird markets have been identified to play a critical role. In this repeated cross-sectional study, we combined surveillance data collected monthly on Jakarta's live bird markets over a five-year period, with risk factors related to the structure and management of live bird markets, the trading and slaughtering of birds at these markets, and environmental and demographic conditions in the areas where the markets were located. Over the study period 36.7% (95% CI: 35.1, 38.3) of samples (N = 1315) tested HPAI H5 virus positive. Using General Estimation Equation approaches to account for repeated observations over time, we explored the association between HPAI H5 virus prevalence and potential risk factors. Markets where only live birds and carcasses were sold, but no slaughtering was conducted at or at the vicinity of the markets, had a significantly reduced chance of being positive for H5 virus (OR = 0.2, 95% CI 0.1-0.5). Also, markets, that used display tables for poultry carcasses made from wood, had reduced odds of being H5 virus positive (OR = 0.7, 95% CI 0.5-1.0), while having at least one duck sample included in the pool of samples collected at the market increased the chance of being H5 virus positive (OR = 5.7, 95% CI 3.6-9.2). Markets where parent stock was traded, were more at risk of being H5 virus positive compared to markets where broilers were traded. Finally, the human population density in the district, the average distance between markets and origins of poultry sold at markets and the total rainfall per month were all positively associated with higher H5 virus prevalence. In summary, our results highlight that a combination of factors related to trading and marketing processes and environmental pressures need to be considered to reduce H5 virus infection risk for customers at urban live bird markets. In particular, the relocation of slaughter areas to well-managed separate locations should be considered.


Assuntos
Virus da Influenza A Subtipo H5N1/patogenicidade , Influenza Aviária/epidemiologia , Doenças das Aves Domésticas/epidemiologia , Animais , Galinhas/virologia , Patos/virologia , Monitoramento Ambiental , Humanos , Indonésia/epidemiologia , Vírus da Influenza A , Influenza Aviária/transmissão , Influenza Aviária/virologia , Aves Domésticas/virologia , Doenças das Aves Domésticas/transmissão , Doenças das Aves Domésticas/virologia , Fatores de Risco
14.
Transbound Emerg Dis ; 66(4): 1653-1664, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30964232

RESUMO

Poultry can become infected with low pathogenic avian influenza (LPAI) viruses via (in)direct contact with infected wild birds or by transmission of the virus between farms. This study combines routinely collected surveillance data with genetic analysis to assess the contribution of between-farm transmission to the overall incidence of LPAI virus infections in poultry. Over a 10-year surveillance period, we identified 35 potential cases of between-farm transmission in the Netherlands, of which 10 formed geographical clusters. A total of 21 LPAI viruses were isolated from nine potential between-farm transmission cases, which were further studied by genetic and epidemiological analysis. Whole genome sequence analysis identified close genetic links between infected farms in seven cases. The presence of identical deletions in the neuraminidase stalk region and minority variants provided additional indications of between-farm transmission. Spatiotemporal analysis demonstrated that genetically closely related viruses were detected within a median time interval of 8 days, and the median distance between the infected farms was significantly shorter compared to farms infected with genetically distinct viruses (6.3 versus 69.0 km; p < 0.05). The results further suggest that between-farm transmission was not restricted to holdings of the same poultry type and not related to the housing system. Although separate introductions from the wild bird reservoir cannot be excluded, our study indicates that between-farm transmission occurred in seven of nine virologically analysed cases. Based on these findings, it is likely that between-farm transmission contributes considerably to the incidence of LPAI virus infections in poultry.


Assuntos
Galinhas , Patos , Vírus da Influenza A/fisiologia , Influenza Aviária/epidemiologia , Doenças das Aves Domésticas/epidemiologia , Perus , Criação de Animais Domésticos , Animais , Monitoramento Epidemiológico , Fazendas , Feminino , Incidência , Influenza Aviária/transmissão , Influenza Aviária/virologia , Países Baixos/epidemiologia , Doenças das Aves Domésticas/transmissão , Doenças das Aves Domésticas/virologia
15.
Influenza Other Respir Viruses ; 13(4): 415-425, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-30884184

RESUMO

BACKGROUND: Few studies have reported on the seroprevalence of antibodies against avian influenza A (H9N2) virus and the incidence of these infections in the northern China and among swine workers. METHODS: We conducted a serological cohort study among people working with poultry or swine or the general population in Beijing, China. It comprised four cross-sectional serological surveys in November 2013, April 2014, April 2015, and April 2016. Blood samples collected from the participants were tested for anti-H9N2 antibodies using a hemagglutination-inhibition (HI) assay. Multivariable Poisson regression model was then used to compare the person-month incidence rates for H9N2 viral infections among the three groups, assessed by incidence rate ratio (IRR). RESULTS: In the four cross-sectional surveys, the highest seroprevalence of anti-H9N2 antibodies (HI titer ≥ 80) was recorded in the poultry workers (2.77%, 19/685) in April 2016, while the lowest was recorded in the general population (0.09%, 1/1135) in April 2015. The highest incidence density rate for H9N2 infections across the whole study period was recorded among the poultry workers (3.75/1000 person-months), followed by the swine workers (1.94/1000 person-months) and the general population (1.78/1000 person-months). Multivariable analysis showed that the poultry workers were at higher risk (IRR: 2.42, 95% CI: 1.07-5.48; P = 0.034) of contracting H9N2 virus than the general population. CONCLUSIONS: Although the seroprevalence of H9N2 antibodies was low in Beijing, the poultry workers were at higher risk of contracting H9N2 viral infections than the general population. Closer monitoring and strengthened protection measures for poultry workers are warranted.


Assuntos
Fazendeiros/estatística & dados numéricos , Vírus da Influenza A Subtipo H9N2/isolamento & purificação , Influenza Aviária/virologia , Influenza Humana/epidemiologia , Adulto , Animais , Anticorpos Antivirais/sangue , China/epidemiologia , Estudos de Coortes , Estudos Transversais , Feminino , Testes de Inibição da Hemaglutinação , Humanos , Influenza Aviária/transmissão , Influenza Humana/transmissão , Masculino , Pessoa de Meia-Idade , Aves Domésticas/virologia , Fatores de Risco , Estudos Soroepidemiológicos , Suínos/virologia
16.
Comput Math Methods Med ; 2019: 9248246, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30881481

RESUMO

In 2013 in mainland China, a novel avian influenza virus H7N9 began to infect humans and had aroused severe fatality in the infected humans, followed by the annual outbreaks. By methods of GIS and kriging interpolation, we get the geographical distributions. We obtain the longitudinal characteristics of these outbreaks based on statistics and diagrams. After these spatiotemporal distributions, an eco-epidemiological model is established and analyzed. In this model, the general incidence functions, the factor of fully killed infected poultry, and the virus in environment are taken into account. Theoretical analysis shows that the endemic will be formed to a large extent once the H7N9 avian influenza virus exists in poultry. On the basis of dynamics, we explore the possible disease control measures by numerical simulations. Simulations indicate that measures of vaccination in poultry and stopping live poultry transactions are the primary choices for disease control in humans, and strengthened inhibition effects and environmental disinfections can effectively control the outbreak.


Assuntos
Subtipo H7N9 do Vírus da Influenza A , Influenza Humana/epidemiologia , Influenza Humana/virologia , Animais , China/epidemiologia , Controle de Doenças Transmissíveis , Simulação por Computador , Surtos de Doenças , Epidemias , Geografia , Humanos , Influenza Aviária/epidemiologia , Influenza Aviária/transmissão , Influenza Aviária/virologia , Influenza Humana/transmissão , Aves Domésticas , Fatores de Tempo , Organização Mundial da Saúde
17.
Viruses ; 11(3)2019 03 22.
Artigo em Inglês | MEDLINE | ID: mdl-30909490

RESUMO

Significantly higher numbers of human infections with H5N1 virus have occurred in Indonesia and Egypt, compared with other affected areas, and it is speculated that there are specific viral factors for human infection with avian H5N1 viruses in these locations. We previously showed PB2-K526R is present in 80% of Indonesian H5N1 human isolates, which lack the more common PB2-E627K substitution. Testing the hypothesis that this mutation may prime avian H5N1 virus for human infection, we showed that: (1) K526R is rarely found in avian influenza viruses but was identified in H5N1 viruses 2⁻3 years after the virus emerged in Indonesia, coincident with the emergence of H5N1 human infections in Indonesia; (2) K526R is required for efficient replication of Indonesia H5N1 virus in mammalian cells in vitro and in vivo and reverse substitution to 526K in human isolates abolishes this ability; (3) Indonesian H5N1 virus, which contains K526R-PB2, is stable and does not further acquire E627K following replication in infected mice; and (4) virus containing K526R-PB2 shows no fitness deficit in avian species. These findings illustrate an important mechanism in which a host adaptive mutation that predisposes avian H5N1 virus towards infecting humans has arisen with the virus becoming prevalent in avian species prior to human infections occurring. A similar mechanism is observed in the Qinghai-lineage H5N1 viruses that have caused many human cases in Egypt; here, E627K predisposes towards human infections. Surveillance should focus on the detection of adaptation markers in avian strains that prime for human infection.


Assuntos
Interações Hospedeiro-Patógeno/genética , Virus da Influenza A Subtipo H5N1/genética , Influenza Aviária/transmissão , Mutação de Sentido Incorreto , Proteínas Virais/genética , Adaptação Fisiológica , Substituição de Aminoácidos , Animais , Aves , Egito , Humanos , Indonésia , Virus da Influenza A Subtipo H5N1/enzimologia , Influenza Aviária/virologia , Influenza Humana/virologia , Camundongos , Camundongos Endogâmicos BALB C , Replicação Viral
18.
Virus Genes ; 55(3): 411-414, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30895439

RESUMO

In 2017, an H7N8 avian influenza virus (AIV) was isolated from a domestic duck from a farm in Central China. Sequences analysis showed that this strain received its genes from H7, H1, H2, H3, H5, and H6 AIVs of domestic poultry and wild birds in Asia. It exhibited low pathogenicity in chickens and mild pathogenicity in mice. These results suggest the importance of continued surveillance of the H7N8 virus to better understand the ecology and evolution of the AIVs in poultry and wild birds and the potential threat to human health.


Assuntos
Patos/virologia , Vírus da Influenza A/genética , Influenza Aviária/virologia , Influenza Humana/virologia , Doenças das Aves Domésticas/virologia , Animais , Animais Domésticos/virologia , Animais Selvagens , Galinhas/virologia , China , Humanos , Vírus da Influenza A/patogenicidade , Influenza Aviária/transmissão , Influenza Humana/transmissão , Camundongos , Filogenia , Aves Domésticas/virologia , Doenças das Aves Domésticas/transmissão
19.
BMC Infect Dis ; 19(1): 138, 2019 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-30744562

RESUMO

BACKGROUND: With an increased incidence of viral zoonoses, there is an impetus to strengthen collaborations between public health, agricultural and environmental departments. This interdisciplinary cooperation, also known as the 'One Health' approach, has received significant support from various stakeholders. However, current efforts and policies still fall short of those needed for an effective One Health approach towards disease control and prevention. The avian-origin H7N9 influenza A virus outbreak in China serves as an ideal case study to emphasise this point. DISCUSSION: Here, we present the features and epidemiology of human infections with H7N9 influenza virus. At the early stages of the H7N9 epidemic, there was limited virus surveillance and limited prevention measures implemented in live poultry markets. As a result, zoonotic infections with H7N9 influenza viruses continued to enlarge in both numbers and geographic distribution. It was only after the number of human infections with H7N9 influenza virus spiked in the 5th wave of the epidemic that inter-departmental alliances were formed. This resulted in the rapid control of the number of human infections. We therefore further discuss the barriers that prevented the implementation of an effective One Health approach in China and what this means for other emerging, zoonotic viral diseases. Effective implementation of evidence-based disease management approaches in China will result in substantial health and economic gains. The continual threat of avian influenza, as well as other emerging zoonotic viral infections, emphasizes the need to remove the barriers that prevent the effective implementation of One Health policies in disease management.


Assuntos
Surtos de Doenças/prevenção & controle , Subtipo H7N9 do Vírus da Influenza A , Influenza Aviária/transmissão , Influenza Humana/prevenção & controle , Saúde Única , Animais , China/epidemiologia , Humanos , Influenza Aviária/virologia , Influenza Humana/epidemiologia , Influenza Humana/virologia , Aves Domésticas/virologia , Saúde Pública , Zoonoses/epidemiologia , Zoonoses/prevenção & controle , Zoonoses/transmissão
20.
Viruses ; 11(2)2019 02 16.
Artigo em Inglês | MEDLINE | ID: mdl-30781528

RESUMO

Low pathogenic avian influenza (LPAI) viruses can silently circulate in poultry and wild aquatic birds and potentially mutate into highly pathogenic avian influenza (HPAI) viruses. In the U.S., recent emergence and spread of H7N8 and H7N9 HPAI viruses not only caused devastating losses to domestic poultry but also underscored the capability of LPAI viruses to mutate into HPAI viruses. Therefore, in this study, we evaluated pathogenicity and transmissibility of H7N8 and H7N9 LPAI viruses (the progenitors of HPAI viruses) in chickens and turkeys. We also included H7N2 isolated from an outbreak of LPAI in commercial chickens. H7 viruses replicated more efficiently in the respiratory tract than in the gastrointestinal tract, suggesting that their replication is restricted to the upper respiratory tract. Specifically, H7N2 replicated most efficiently in two-week-old chickens and turkeys. In contrast, H7N8 replicated least efficiently in those birds. Further, replication of H7N2 and H7N9 was restricted in the upper respiratory tract of four-week-old specific-pathogen-free (SPF) and broiler chickens. Despite their restricted replication, the two viruses efficiently transmitted from infected to naïve birds by direct contact, leading to seroconversion of contacted chickens. Our findings suggest the importance of continuous monitoring and surveillance of LPAI viruses in the fields.


Assuntos
Galinhas/virologia , Vírus da Influenza A/patogenicidade , Influenza Aviária/transmissão , Doenças das Aves Domésticas/transmissão , Perus/virologia , Replicação Viral , Animais , Trato Gastrointestinal/virologia , Vírus da Influenza A Subtipo H7N2/patogenicidade , Vírus da Influenza A Subtipo H7N2/fisiologia , Subtipo H7N9 do Vírus da Influenza A/patogenicidade , Subtipo H7N9 do Vírus da Influenza A/fisiologia , Influenza Aviária/virologia , Doenças das Aves Domésticas/virologia , Sistema Respiratório/virologia , Organismos Livres de Patógenos Específicos
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