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1.
Viruses ; 13(2)2021 02 08.
Artigo em Inglês | MEDLINE | ID: mdl-33567525

RESUMO

Avian influenza virus (AIV) subtypes H5 and H7 are capable of mutating from low to high pathogenicity strains, causing high mortality in poultry with significant economic losses globally. During 2015, two outbreaks of H7N7 low pathogenicity AIV (LPAIV) in Germany, and one each in the United Kingdom (UK) and The Netherlands occurred, as well as single outbreaks of H7N7 high pathogenicity AIV (HPAIV) in Germany and the UK. Both HPAIV outbreaks were linked to precursor H7N7 LPAIV outbreaks on the same or adjacent premises. Herein, we describe the clinical, epidemiological, and virological investigations for the H7N7 UK HPAIV outbreak on a farm with layer chickens in mixed free-range and caged units. H7N7 HPAIV was identified and isolated from clinical samples, as well as H7N7 LPAIV, which could not be isolated. Using serological and molecular evidence, we postulate how the viruses spread throughout the premises, indicating potential points of incursion and possible locations for the mutation event. Serological and mortality data suggested that the LPAIV infection preceded the HPAIV infection and afforded some clinical protection against the HPAIV. These results document the identification of a LPAIV to HPAIV mutation in nature, providing insights into factors that drive its manifestation during outbreaks.


Assuntos
Vírus da Influenza A Subtipo H7N7/genética , Vírus da Influenza A Subtipo H7N7/patogenicidade , Influenza Aviária/virologia , Doenças das Aves Domésticas/virologia , Animais , Anticorpos Antivirais/sangue , Galinhas , Surtos de Doenças/veterinária , Fazendas , Genoma Viral/genética , Glicoproteínas de Hemaglutininação de Vírus da Influenza/genética , Glicoproteínas de Hemaglutininação de Vírus da Influenza/imunologia , Vírus da Influenza A Subtipo H7N7/classificação , Vírus da Influenza A Subtipo H7N7/imunologia , Influenza Aviária/epidemiologia , Influenza Aviária/patologia , Influenza Aviária/transmissão , Mutação , Filogenia , Doenças das Aves Domésticas/epidemiologia , Doenças das Aves Domésticas/patologia , Doenças das Aves Domésticas/transmissão , Reino Unido/epidemiologia , Eliminação de Partículas Virais/genética
2.
Viruses ; 13(2)2021 02 10.
Artigo em Inglês | MEDLINE | ID: mdl-33579009

RESUMO

Highly pathogenic avian influenza (HPAI), a zoonotic disease, is a major threat to humans and poultry health worldwide. In January 2014, HPAI virus subtype H5N8 first infected poultry farms in South Korea, and 393 outbreaks, overall, were reported with enormous economic damage in the poultry industry. We analyzed the spatiotemporal distribution of HPAI H5N8 outbreaks in poultry farms using the global and local spatiotemporal interaction analyses in the first (January to July 2014) and second (September 2014 to June 2015) outbreak waves. The space-time K-function analyses revealed significant interactions within three days and in an over-40 km space-time window between the two study periods. The excess risk attributable value (D0) was maintained despite the distance in the case of HPAI H5N8 in South Korea. Eleven spatiotemporal clusters were identified, and the results showed that the HPAI introduction was from the southwestern region, and spread to the middle region, in South Korea. This spatiotemporal interaction indicates that the HPAI epidemic in South Korea was mostly characterized by short period transmission, regardless of the distance. This finding supports strict control strategies such as preemptive depopulation, and poultry movement tracking. Further studies are needed to understand HPAI disease transmission patterns.


Assuntos
Surtos de Doenças/veterinária , Vírus da Influenza A Subtipo H5N8/patogenicidade , Influenza Aviária/transmissão , Doenças das Aves Domésticas/transmissão , Animais , Análise por Conglomerados , Surtos de Doenças/prevenção & controle , Fazendas , Influenza Aviária/epidemiologia , Influenza Aviária/prevenção & controle , Aves Domésticas , Doenças das Aves Domésticas/epidemiologia , Doenças das Aves Domésticas/prevenção & controle , República da Coreia/epidemiologia , Análise Espaço-Temporal
3.
Viruses ; 13(2)2021 01 24.
Artigo em Inglês | MEDLINE | ID: mdl-33498851

RESUMO

Wild birds are considered the natural reservoir of influenza A viruses (IAVs) making them critical for IAV surveillance efforts. While sea ducks have played a role in novel IAV emergence events that threatened food security and public health, very few surveillance samples have been collected from sea duck hosts. From 2014-2018, we conducted surveillance focused in the Mississippi flyway, USA at locations where sea duck harvest has been relatively successful compared to our other sampling locations. Our surveillance yielded 1662 samples from sea ducks, from which we recovered 77 IAV isolates. Our analyses identified persistence of sea duck specific IAV lineages across multiple years. We also recovered sea duck origin IAVs containing an H4 gene highly divergent from the majority of North American H4-HA with clade node age of over 65 years. Identification of IAVs with long branch lengths is indicative of substantial genomic change consistent with persistence without detection by surveillance efforts. Sea ducks play a role in the movement and long-term persistence of IAVs and are likely harboring more undetected IAV diversity. Sea ducks should be a point of emphasis for future North American wild bird IAV surveillance efforts.


Assuntos
Patos/virologia , Glicoproteínas de Hemaglutininação de Vírus da Influenza/genética , Vírus da Influenza A/genética , Influenza Aviária/epidemiologia , Animais , Animais Selvagens/virologia , Genômica , Especificidade de Hospedeiro , Vírus da Influenza A/isolamento & purificação , Influenza Aviária/virologia , Filogenia , Aves Domésticas , Estados Unidos/epidemiologia
4.
Viruses ; 12(12)2020 12 14.
Artigo em Inglês | MEDLINE | ID: mdl-33327524

RESUMO

Global dispersion of high pathogenicity avian influenza (HPAI), especially that caused by H5 clade 2.3.4.4, has threatened poultry industries and, potentially, human health. An HPAI virus, A/northern pintail/Hokkaido/M13/2020 (H5N8) (NP/Hok/20) belonging to clade 2.3.4.4b, was isolated from a fecal sample collected at a lake in Hokkaido, Japan where migratory birds rested, October 2020. In the phylogenetic trees of all eight gene segments, NP/Hok/20 fell into in the cluster of European isolates in 2020, but was distinct from the isolates in eastern Asia and Europe during the winter season of 2017-2018. The antigenic cartography indicates that the antigenicity of NP/Hok/20 was almost the same as that of previous isolates of H5 clade 2.3.4.4b, whereas the antigenic distances from NP/Hok/20 to the representative strains in clade 2.3.4.4e and to a strain in 2.3.4 were apparently distant. These data imply that HPAI virus clade 2.3.4.4b should have been delivered by bird migration despite the intercontinental distance, although it was not defined whether NP/Hok/20 was transported from Europe via Siberia where migratory birds nest in the summer season. Given the probability of perpetuation of transmission in the northern territory, periodic updates of intensive surveys on avian influenza at the global level are essential to prepare for future outbreaks of the HPAI virus.


Assuntos
Genótipo , Vírus da Influenza A Subtipo H5N8/genética , Vírus da Influenza A Subtipo H5N8/patogenicidade , Influenza Aviária/epidemiologia , Influenza Aviária/virologia , Animais , Animais Selvagens/virologia , Patos , Geografia Médica , História do Século XXI , Vírus da Influenza A Subtipo H5N8/classificação , Vírus da Influenza A , Influenza Aviária/história , Japão/epidemiologia , Filogenia , Virulência
5.
Viruses ; 13(1)2020 12 26.
Artigo em Inglês | MEDLINE | ID: mdl-33375376

RESUMO

Influenza A virus subtype H1N1 has caused global pandemics like the "Spanish flu" in 1918 and the 2009 H1N1 pandemic several times. H1N1 remains in circulation and survives in multiple animal sources, including wild birds. Surveillance during the winter of 2018-2019 in Korea revealed two H1N1 isolates in samples collected from wild bird feces: KNU18-64 (A/Greater white-fronted goose/South Korea/KNU18-64/2018(H1N1) and WKU19-4 (A/wild bird/South Korea/WKU19-4/2019(H1N1). Phylogenetic analysis indicated that M gene of KNU18-64(H1N1) isolate resembles that of the Alaskan avian influenza virus, whereas WKU19-4(H1N1) appears to be closer to the Mongolian virus. Molecular characterization revealed that they harbor the amino acid sequence PSIQRSGLF and are low-pathogenicity influenza viruses. In particular, the two isolates harbored three different mutation sites, indicating that they have different virulence characteristics. The mutations in the PB1-F2 and PA protein of WKU19-4(H1N1) indicate increasing polymerase activity. These results corroborate the kinetic growth data for WKU19-4 in MDCK cells: a dramatic increase in the viral titer after 12 h post-inoculation compared with that in the control group H1N1 (CA/04/09(pdm09)). The KNU18-64(H1N1) isolate carries mutations indicating an increase in mammal adaptation; this characterization was confirmed by the animal study in mice. The KNU18-64(H1N1) group showed the presence of viruses in the lungs at days 3 and 6 post-infection, with titers of 2.71 ± 0.16 and 3.71 ± 0.25 log10(TCID50/mL), respectively, whereas the virus was only detected in the WKU19-4(H1N1) group at day 6 post-infection, with a lower titer of 2.75 ± 0.51 log10(TCID50/mL). The present study supports the theory that there is a relationship between Korea and America with regard to reassortment to produce novel viral strains. Therefore, there is a need for increased surveillance of influenza virus circulation in free-flying and wild land-based birds in Korea, particularly with regard to Alaskan and Asian strains.


Assuntos
Animais Selvagens , Patos/virologia , Vírus da Influenza A Subtipo H1N1/classificação , Vírus da Influenza A Subtipo H1N1/genética , Influenza Aviária/epidemiologia , Influenza Aviária/virologia , Vírus Reordenados , Animais , Cães , Feminino , Genoma Viral , Genômica/métodos , História do Século XXI , Especificidade de Hospedeiro , Vírus da Influenza A Subtipo H1N1/isolamento & purificação , Influenza Aviária/história , Influenza Aviária/patologia , Células Madin Darby de Rim Canino , Camundongos , Filogenia , Vigilância em Saúde Pública , República da Coreia/epidemiologia
6.
Front Immunol ; 11: 552909, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33013925

RESUMO

The 2019 novel coronavirus (SARS-CoV-2) pandemic has caused a global health emergency. The outbreak of this virus has raised a number of questions: What is SARS-CoV-2? How transmissible is SARS-CoV-2? How severely affected are patients infected with SARS-CoV-2? What are the risk factors for viral infection? What are the differences between this novel coronavirus and other coronaviruses? To answer these questions, we performed a comparative study of four pathogenic viruses that primarily attack the respiratory system and may cause death, namely, SARS-CoV-2, severe acute respiratory syndrome (SARS-CoV), Middle East respiratory syndrome (MERS-CoV), and influenza A viruses (H1N1 and H3N2 strains). This comparative study provides a critical evaluation of the origin, genomic features, transmission, and pathogenicity of these viruses. Because the coronavirus disease 2019 (COVID-19) pandemic caused by SARS-CoV-2 is ongoing, this evaluation may inform public health administrators and medical experts to aid in curbing the pandemic's progression.


Assuntos
Betacoronavirus/genética , Infecções por Coronavirus/epidemiologia , Vírus da Influenza A Subtipo H1N1/genética , Vírus da Influenza A Subtipo H3N2/genética , Influenza Humana/epidemiologia , Coronavírus da Síndrome Respiratória do Oriente Médio/genética , Pneumonia Viral/epidemiologia , Vírus da SARS/genética , Síndrome Respiratória Aguda Grave/epidemiologia , Animais , Betacoronavirus/patogenicidade , Aves/virologia , Infecções por Coronavirus/transmissão , Infecções por Coronavirus/virologia , Genoma Viral , Humanos , Vírus da Influenza A Subtipo H1N1/patogenicidade , Vírus da Influenza A Subtipo H3N2/patogenicidade , Influenza Aviária/epidemiologia , Influenza Aviária/transmissão , Influenza Aviária/virologia , Influenza Humana/transmissão , Influenza Humana/virologia , Coronavírus da Síndrome Respiratória do Oriente Médio/patogenicidade , Pandemias , Pneumonia Viral/transmissão , Pneumonia Viral/virologia , Vírus da SARS/patogenicidade , Síndrome Respiratória Aguda Grave/transmissão , Síndrome Respiratória Aguda Grave/virologia , Virulência/imunologia
7.
Biomed Environ Sci ; 33(9): 670-679, 2020 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-33106212

RESUMO

Objective: In China, 24 cases of human infection with highly pathogenic avian influenza (HPAI) H5N6 virus have been confirmed since the first confirmed case in 2014. Therefore, we developed and assessed two H5N6 candidate vaccine viruses (CVVs). Methods: In accordance with the World Health Organization (WHO) recommendations, we constructed two reassortant viruses using reverse genetics (RG) technology to match the two different epidemic H5N6 viruses. We performed complete genome sequencing to determine the genetic stability. We assessed the growth ability of the studied viruses in MDCK cells and conducted a hemagglutination inhibition assay to analyze their antigenicity. Pathogenicity attenuation was also evaluated in vitro and in vivo. Results: The results showed that no mutations occurred in hemagglutinin or neuraminidase, and both CVVs retained their original antigenicity. The replication capacity of the two CVVs reached a level similar to that of A/Puerto Rico/8/34 in MDCK cells. The two CVVs showed low pathogenicity in vitro and in vivo, which are in line with the WHO requirements for CVVs. Conclusion: We obtained two genetically stable CVVs of HPAI H5N6 with high growth characteristics, which may aid in our preparedness for a potential H5N6 pandemic.


Assuntos
Vírus da Influenza A/imunologia , Vacinas contra Influenza/imunologia , Influenza Aviária/epidemiologia , Influenza Aviária/prevenção & controle , Influenza Humana/epidemiologia , Influenza Humana/prevenção & controle , Pandemias/prevenção & controle , Animais , Aves , China , Humanos
8.
PLoS One ; 15(9): e0238815, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32913363

RESUMO

The Philippines confirmed its first epidemic of Highly Pathogenic Avian Influenza (HPAI) on August 11, 2017. It ended in November of 2017. Despite the successful management of the epidemic, reemergence is a continuous threat. The aim of this study was to conduct a mathematical model to assess the spatial transmission of HPAI among poultry farms in Central Luzon. Different control strategies and the current government protocol of 1 km radius pre-emptive culling (PEC) from infected farms were evaluated. The alternative strategies include 0.5km PEC, 1.5km PEC, 2 km PEC, 2.5 km PEC, and 3 km PEC, no pre-emptive culling (NPEC). The NPEC scenario was further modeled with a time of government notification set at 24hours, 48 hours, and 72 hours after the detection. Disease spread scenarios under each strategy were generated using an SEIR (susceptible-exposed-infectious-removed) stochastic model. A spatial transmission kernel was calculated and used to represent all potential routes of infection between farms. We assumed that the latent period occurs between 1-2 days, disease detection at 5-7 days post-infection, notification of authorities at 5-7 days post-detection and start of culling at 1-3 days post notification. The epidemic scenarios were compared based on the number of infected farms, the total number of culled farms, and the duration of the epidemic. Our results revealed that the current protocol is the most appropriate option compared with the other alternative interventions considered among farms with reproductive ratio (Ri) > 1. Shortening the culling radius to 0.5 km increased the duration of the epidemic. Further increase in the PEC zone decreased the duration of the epidemic but may not justify the increased number of farms to be culled. Nonetheless, the no-pre-emptive culling (NPEC) strategy can be an effective alternative to the current protocol if farm managers inform the government immediately within 24 hours of observation of the presence of HPAI in their farms. Moreover, if notification is made on days 1-3 after the detection, the scale and length of the outbreak have been significantly reduced. In conclusion, this study provided a comparison of various control measures for confronting the spread of HPAI infection using the simulation model. Policy makers can use this information to enhance the effectiveness of the current control strategy.


Assuntos
Surtos de Doenças/veterinária , Influenza Aviária/epidemiologia , Doenças das Aves Domésticas/virologia , Animais , Surtos de Doenças/prevenção & controle , Epidemias/veterinária , Fazendas , Modelos Biológicos , Modelos Teóricos , Filipinas/epidemiologia , Aves Domésticas , Doenças das Aves Domésticas/prevenção & controle
9.
PLoS One ; 15(8): e0236581, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32790744

RESUMO

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.


Assuntos
Vírus da Influenza A Subtipo H5N2/isolamento & purificação , Vírus da Influenza A Subtipo H5N8/isolamento & purificação , Influenza Aviária/virologia , Doenças das Aves Domésticas/virologia , Aves Domésticas/virologia , Animais , Meio Ambiente , Fazendas , Influenza Aviária/epidemiologia , Doenças das Aves Domésticas/epidemiologia , Fatores de Risco , Taiwan/epidemiologia , Microbiologia da Água
10.
Zhonghua Liu Xing Bing Xue Za Zhi ; 41(7): 1115-1120, 2020 Jul 10.
Artigo em Chinês | MEDLINE | ID: mdl-32741181

RESUMO

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.


Assuntos
Vírus da Influenza A/genética , Influenza Aviária/epidemiologia , Influenza Aviária/virologia , Animais , China/epidemiologia , Evolução Molecular , Vírus da Influenza A/isolamento & purificação , Aves Domésticas
11.
Proc Natl Acad Sci U S A ; 117(34): 20814-20825, 2020 08 25.
Artigo em Inglês | MEDLINE | ID: mdl-32769208

RESUMO

Highly pathogenic avian influenza (HPAI) viruses of the H5 A/goose/Guangdong/1/96 lineage can cause severe disease in poultry and wild birds, and occasionally in humans. In recent years, H5 HPAI viruses of this lineage infecting poultry in Asia have spilled over into wild birds and spread via bird migration to countries in Europe, Africa, and North America. In 2016/2017, this spillover resulted in the largest HPAI epidemic on record in Europe and was associated with an unusually high frequency of reassortments between H5 HPAI viruses and cocirculating low-pathogenic avian influenza viruses. Here, we show that the seven main H5 reassortant viruses had various combinations of gene segments 1, 2, 3, 5, and 6. Using detailed time-resolved phylogenetic analysis, most of these gene segments likely originated from wild birds and at dates and locations that corresponded to their hosts' migratory cycles. However, some gene segments in two reassortant viruses likely originated from domestic anseriforms, either in spring 2016 in east China or in autumn 2016 in central Europe. Our results demonstrate that, in addition to domestic anseriforms in Asia, both migratory wild birds and domestic anseriforms in Europe are relevant sources of gene segments for recent reassortant H5 HPAI viruses. The ease with which these H5 HPAI viruses reassort, in combination with repeated spillovers of H5 HPAI viruses into wild birds, increases the risk of emergence of a reassortant virus that persists in wild bird populations yet remains highly pathogenic for poultry.


Assuntos
Virus da Influenza A Subtipo H5N1/genética , Influenza Aviária/epidemiologia , Vírus Reordenados/genética , Animais , Animais Selvagens/virologia , Ásia/epidemiologia , Aves/virologia , Epidemias , Europa (Continente)/epidemiologia , Virus da Influenza A Subtipo H5N1/isolamento & purificação , Influenza Aviária/virologia , Filogenia , Aves Domésticas/virologia , Vírus Reordenados/isolamento & purificação
12.
Avian Pathol ; 49(6): 529-531, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32720513

RESUMO

COVID-19 should be a "call to arms" for the poultry industry to reassess containment of the H9N2 subtype of low pathogenicity avian influenza viruses. Strains of this virus are a human pandemic threat and a severe economic burden on poultry production. Over the past 20 years they have spread throughout Asia, Africa, Middle East and parts of Europe. As a global industry, a critical need is to re-imagine production and marketing chains, especially in low and middle-income countries, where the structure of much of the industry facilitates virus transmission, especially, but not only, in improperly managed live poultry markets and related value chains. Better, appropriately matched vaccines are needed to support this process but such vaccines cannot, alone, overcome the existing defects in biosecurity, including high farm densities. None of this will occur unless the threat posed by this virus to global health security is recognized.


Assuntos
Betacoronavirus , Infecções por Coronavirus/epidemiologia , Vírus da Influenza A Subtipo H9N2 , Influenza Aviária/virologia , Influenza Humana/virologia , Pneumonia Viral/epidemiologia , Animais , Aves , Infecções por Coronavirus/virologia , Saúde Global , Humanos , Influenza Aviária/epidemiologia , Influenza Aviária/prevenção & controle , Influenza Humana/epidemiologia , Influenza Humana/prevenção & controle , Pandemias , Pneumonia Viral/virologia , Aves Domésticas/virologia
13.
PLoS Comput Biol ; 16(7): e1008009, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32628659

RESUMO

Transmission of infectious diseases between immobile hosts (e.g., plants, farms) is strongly dependent on the spatial distribution of hosts and the distance-dependent probability of transmission. As the interplay between these factors is poorly understood, we use spatial process and transmission modelling to investigate how epidemic size is shaped by host clustering and spatial range of transmission. We find that for a given degree of clustering and individual-level infectivity, the probability that an epidemic occurs after an introduction is generally higher if transmission is predominantly local. However, local transmission also impedes transfer of the infection to new clusters. A consequence is that the total number of infections is maximal if the range of transmission is intermediate. In highly clustered populations, the infection dynamics is strongly determined by the probability of transmission between clusters of hosts, whereby local clusters act as multiplier of infection. We show that in such populations, a metapopulation model sometimes provides a good approximation of the total epidemic size, using probabilities of local extinction, the final size of infections in local clusters, and probabilities of cluster-to-cluster transmission. As a real-world example we analyse the case of avian influenza transmission between poultry farms in the Netherlands.


Assuntos
Surtos de Doenças , Transmissão de Doença Infecciosa , Infectologia/tendências , Algoritmos , Criação de Animais Domésticos , Animais , Análise por Conglomerados , Fazendas , Infectologia/métodos , Influenza Aviária/epidemiologia , Influenza Aviária/transmissão , Modelos Biológicos , Países Baixos , Distribuição Normal , Dinâmica Populacional , Aves Domésticas , Probabilidade , Modelos de Riscos Proporcionais , Risco
14.
J Neuropathol Exp Neurol ; 79(8): 823-842, 2020 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-32647884

RESUMO

Biological evolution of the microbiome continually drives the emergence of human viral pathogens, a subset of which attack the nervous system. The sheer number of pathogens that have appeared, along with their abundance in the environment, demand our attention. For the most part, our innate and adaptive immune systems have successfully protected us from infection; however, in the past 5 decades, through pathogen mutation and ecosystem disruption, a dozen viruses emerged to cause significant neurologic disease. Most of these pathogens have come from sylvatic reservoirs having made the energetically difficult, and fortuitously rare, jump into humans. But the human microbiome is also replete with agents already adapted to the host that need only minor mutations to create neurotropic/toxic agents. While each host/virus symbiosis is unique, this review examines virologic and immunologic principles that govern the pathogenesis of different viral CNS infections that were described in the past 50 years (Influenza, West Nile Virus, Zika, Rift Valley Fever Virus, Hendra/Nipah, Enterovirus-A71/-D68, Human parechovirus, HIV, and SARS-CoV). Knowledge of these pathogens provides us the opportunity to respond and mitigate infection while at the same time prepare for inevitable arrival of unknown agents.


Assuntos
Viroses do Sistema Nervoso Central/epidemiologia , Viroses do Sistema Nervoso Central/transmissão , Zoonoses/epidemiologia , Zoonoses/transmissão , Animais , Aves , Viroses do Sistema Nervoso Central/prevenção & controle , Ecossistema , Humanos , Influenza Aviária/epidemiologia , Influenza Aviária/prevenção & controle , Influenza Aviária/transmissão , Influenza Humana/epidemiologia , Influenza Humana/prevenção & controle , Influenza Humana/transmissão , Febre do Nilo Ocidental/epidemiologia , Febre do Nilo Ocidental/prevenção & controle , Febre do Nilo Ocidental/transmissão , Infecção por Zika virus/epidemiologia , Infecção por Zika virus/prevenção & controle , Infecção por Zika virus/transmissão , Zoonoses/prevenção & controle
15.
Avian Dis ; 64(2): 109-122, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32550610

RESUMO

Alaska represents a globally important region for the ecology of avian-origin influenza A viruses (IAVs) given the expansive wetlands in this region, which serve as habitat for numerous hosts of IAVs that disperse among four continents during the annual cycle. Extensive sampling of wild birds for IAVs in Alaska since 1991 has greatly extended inference regarding intercontinental viral exchange between North America and East Asia and the importance of Beringian endemic species to IAV ecology within this region. Data on IAVs in aquatic birds inhabiting Alaska have also been useful for helping to establish global patterns of prevalence in wild birds and viral dispersal across the landscape. In this review, we summarize the main findings from investigations of IAVs in wild birds and wetlands of Alaska with the aim of providing readers with an understanding of viral ecology within this region. More specifically, we review viral detections, evidence of IAV exposure, and genetic characterization of isolates derived from wild bird samples collected in Alaska by host taxonomy. Additionally, we provide a short overview of wetland complexes within Alaska that may be important to IAV ecology at the continental scale.


Assuntos
Aves , Vírus da Influenza A/isolamento & purificação , Influenza Aviária , Alaska/epidemiologia , Animais , Animais Selvagens , Incidência , Vírus da Influenza A/genética , Vírus da Influenza A/fisiologia , Influenza Aviária/epidemiologia , Influenza Aviária/transmissão , Influenza Aviária/virologia , Prevalência , Áreas Alagadas
16.
Avian Dis ; 64(2): 135-142, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32550613

RESUMO

Aquatic wild birds, especially waterfowl, have been long considered the main reservoirs of the avian influenza A virus; however, recent surveys have found an important prevalence of these viruses among land birds as well. Migration has been suggested as an important factor in the avian influenza virus dissemination. We aimed to estimate the prevalence of influenza A viruses in wild birds (waterbirds and land birds; resident and migratory) in eastern Mexico, where the three main North American migration flyways converge and where there was no previous information on this subject. We detected influenza with reverse transcription coupled with a PCR approach. Of the 534 birds sampled between 2010 and 2012, we detected the influenza A virus in a high proportion of birds (39%). Prevalence was particularly high in land birds (49%) when compared to aquatic birds (26%); there was no difference in overall prevalence between resident (39%) and migratory birds (39%). The high prevalence of the avian influenza virus in land birds was noteworthy in the innermost sampling areas in northern Mexico (Coahuila [82%] and Nuevo Leon [43%]).


Assuntos
Aves , Vírus da Influenza A/isolamento & purificação , Influenza Aviária/epidemiologia , Migração Animal , Animais , Influenza Aviária/virologia , México/epidemiologia , Prevalência , Reação em Cadeia da Polimerase Via Transcriptase Reversa/veterinária
17.
J Vet Sci ; 21(3): e34, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32476310

RESUMO

BACKGROUND: A nationwide outbreak of foot-and-mouth disease (FMD) in South Korea caused massive economic losses in 2010. Since then, the Animal and Plant Quarantine Agency (QIA) has enhanced disinfection systems regarding livestock to prevent horizontal transmission of FMD and Avian influenza (AI). Although the amount of disinfectant used continues to increase, cases of FMD and AI have been occurring annually in Korea, except 2012 and 2013. OBJECTIVES: This study measured the concentration of the disinfectant to determine why it failed to remove the horizontal transmission despite increased disinfectant use. METHODS: Surveys were conducted from February to May 2017, collecting 348 samples from disinfection systems. The samples were analyzed using the Standards of Animal Health Products analysis methods from QIA. RESULTS: Twenty-three facilities used inappropriate or non-approved disinfectants. Nearly all sampled livestock farms and facilities-93.9%-did not properly adjust the disinfectant concentration. The percentage using low concentrations, or where no effective substance was detected, was 46.9%. Furthermore, 13 samples from the official disinfection station did not use effective disinfectant, and-among 72 samples from the disinfection station-88.89% were considered inappropriate concentration, according to the foot-and-mouth disease virus guidelines; considering the AIV guideline, 73.61% were inappropriate concentrations. Inappropriate concentration samples on automatic (90.00%) and semi-automatic (90.90%) disinfection systems showed no significant difference from manual methods (88.24%). Despite this study being conducted during the crisis level, most disinfectants were used inappropriately. CONCLUSIONS: This may partially explain why horizontal transmission of FMD and AI cannot be effectively prevented despite extensive disinfectant use.


Assuntos
Doenças dos Bovinos , Surtos de Doenças/veterinária , Desinfetantes/farmacologia , Febre Aftosa , Influenza Aviária , Doenças das Aves Domésticas , Doenças dos Suínos , Animais , Bovinos , Doenças dos Bovinos/epidemiologia , Doenças dos Bovinos/prevenção & controle , Doenças dos Bovinos/transmissão , Doenças dos Bovinos/virologia , Galinhas , Surtos de Doenças/prevenção & controle , Patos , Febre Aftosa/epidemiologia , Febre Aftosa/prevenção & controle , Febre Aftosa/transmissão , Febre Aftosa/virologia , Vírus da Febre Aftosa/efeitos dos fármacos , Vírus da Influenza A/efeitos dos fármacos , Influenza Aviária/epidemiologia , Influenza Aviária/prevenção & controle , Influenza Aviária/transmissão , Influenza Aviária/virologia , Gado , Doenças das Aves Domésticas/epidemiologia , Doenças das Aves Domésticas/prevenção & controle , Doenças das Aves Domésticas/transmissão , Doenças das Aves Domésticas/virologia , República da Coreia/epidemiologia , Sus scrofa , Suínos , Doenças dos Suínos/epidemiologia , Doenças dos Suínos/prevenção & controle , Doenças dos Suínos/transmissão , Doenças dos Suínos/virologia
18.
Rev Esp Salud Publica ; 942020 Mar 31.
Artigo em Espanhol | MEDLINE | ID: mdl-32381999

RESUMO

Wild waterfowl are considered the main natural reservoir of influenza viruses and they have contributed to the reassortment of both pandemic viruses and viruses responsible for outbreaks of avian influenza in wild and domestic species. In order to determinate the factors involved, we reviewed the human cases of avian influenza related to the management of wild birds, the use of personal protective equipment, as well as the basis of surveillance programs of highly pathogenic avian influenza in wild birds in Spain. The direct transmission of influenza virus from wild birds to humans is a rare event. However, our epidemiological context is influenced by climate change and marked by the presence of migratory routes from territories where infection may be present. Thus and due to the clinical, economical and public health implications that such infections may have, the different groups exposed to wild birds (veterinarians, biologists, ornithologists, conservationists, field technicians, environmental officers, falconers, hunters, etc.) should know which are the possible sources of infection and how to handle the personal protective equipment. Besides, it is important that those groups know the current sanitary situation regarding avian influenza so they can consequently adapt their activities and employ proper protective measures, in addition to providing valuable information for surveillance programs.


Assuntos
Animais Selvagens/virologia , Aves/virologia , Influenza Aviária/transmissão , Influenza Humana/transmissão , Doenças Profissionais , Exposição Ocupacional/estatística & dados numéricos , Zoonoses/transmissão , Animais , Reservatórios de Doenças/virologia , Humanos , Influenza Aviária/epidemiologia , Influenza Aviária/prevenção & controle , Influenza Humana/epidemiologia , Influenza Humana/prevenção & controle , Doenças Profissionais/epidemiologia , Doenças Profissionais/prevenção & controle , Exposição Ocupacional/efeitos adversos , Exposição Ocupacional/prevenção & controle , Equipamento de Proteção Individual , Vigilância em Saúde Pública , Espanha , Zoonoses/epidemiologia , Zoonoses/prevenção & controle
19.
BMC Infect Dis ; 20(1): 369, 2020 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-32448137

RESUMO

BACKGROUND: Previous studies have proven that the closure of live poultry markets (LPMs) was an effective intervention to reduce human risk of avian influenza A (H7N9) infection, but evidence is limited on the impact of scale and duration of LPMs closure on the transmission of H7N9. METHOD: Five cities (i.e., Shanghai, Suzhou, Shenzhen, Guangzhou and Hangzhou) with the largest number of H7N9 cases in mainland China from 2013 to 2017 were selected in this study. Data on laboratory-confirmed H7N9 human cases in those five cities were obtained from the Chinese National Influenza Centre. The detailed information of LPMs closure (i.e., area and duration) was obtained from the Ministry of Agriculture. We used a generalized linear model with a Poisson link to estimate the effect of LPMs closure, reported as relative risk reduction (RRR). We used classification and regression trees (CARTs) model to select and quantify the dominant factor of H7N9 infection. RESULTS: All five cities implemented the LPMs closure, and the risk of H7N9 infection decreased significantly after LPMs closure with RRR ranging from 0.80 to 0.93. Respectively, a long-term LPMs closure for 10-13 weeks elicited a sustained and highly significant risk reduction of H7N9 infection (RRR = 0.98). Short-time LPMs closure with 2 weeks in every epidemic did not reduce the risk of H7N9 infection (p > 0.05). Partially closed LPMs in some suburbs contributed only 35% for reduction rate (RRR = 0.35). Shenzhen implemented partial closure for first 3 epidemics (p > 0.05) and all closure in the latest 2 epidemic waves (RRR = 0.64). CONCLUSION: Our findings suggest that LPMs all closure in whole city can be a highly effective measure comparing with partial closure (i.e. only urban closure, suburb and rural remain open). Extend the duration of closure and consider permanently closing the LPMs will help improve the control effect. The effect of LPMs closure seems greater than that of meteorology on H7N9 transmission.


Assuntos
Epidemias/prevenção & controle , Subtipo H7N9 do Vírus da Influenza A , Influenza Aviária/epidemiologia , Influenza Aviária/transmissão , Influenza Humana/epidemiologia , Aves Domésticas/virologia , Animais , China/epidemiologia , Cidades/epidemiologia , Humanos , Umidade , Incidência , Influenza Aviária/virologia , Influenza Humana/virologia , Modelos Lineares , Distribuição de Poisson , Fatores de Risco , Temperatura , População Urbana
20.
Arch Virol ; 165(6): 1357-1366, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32285202

RESUMO

Since the incursion of avian influenza virus subtype H5N8 in Egypt in late 2016, it has spread rapidly, causing severe losses in poultry production. Multiple introductions of different reassorted strains were observed in 2017. In this study, a genetic characterization of the HA gene was carried out with 31 isolates selected from different governorates and sectors. Fifteen isolates were selected for NA gene sequence analysis. The HA and NA genes were divided into two subgroups (I and II) with positive selection pressure identified at positions 174 and 29, respectively. The HA gene contained two novel mutations in the antigenic sites, A and E. The HA nucleotide sequence identity ranged from 77 to 90% with different vaccine seeds. Full-genome sequence analysis was carried out for eight viruses, representing different governorates and sectors, to identify the predominant reassorted strain in Egypt. All viruses were similar to a reassorted strain of clade 2.3.4.4b that has been identified in Germany, among other countries. Analysis of these viruses revealed mutations specific to Egyptian strains and not the original virus characterized in 2017 (A/duck/Egypt/F446/2017), with a novel antiviral resistance marker, V27A, indicating resistance to amantadine in the M2 protein of two strains. The results indicate increased variability of circulating H5N8 viruses compared to earlier viruses sequenced in 2016 and 2017. The predominant reassorted virus circulating in 2017 and 2018 originated from an early 2017 strain. It is important to continue this surveillance of avian influenza viruses to monitor the evolution of circulating viruses.


Assuntos
Vírus da Influenza A Subtipo H5N8/genética , Influenza Aviária/epidemiologia , Influenza Aviária/virologia , Doenças das Aves Domésticas/epidemiologia , Doenças das Aves Domésticas/virologia , Vírus Reordenados , Animais , Aves/virologia , Surtos de Doenças , Egito/epidemiologia , Genes Virais , Genótipo , Geografia Médica , Vírus da Influenza A Subtipo H5N8/classificação , Filogenia , Aves Domésticas/virologia , RNA Viral
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