From February 2013, a novel avian influenza A H7N9 virus causing human infection with fatal outcomes has been identified in eastern China. This avian influenza A H7N9 virus is a triple reassortant of viruses that are avian-origin only and it is low pathogenic in poultry. Several characteristic amino acid mutations in HA and PB2 polymerase subunit (including G186V, Q226L and E627K substitution) have been found through sequence analysis, and these mutations probably facilitate binding to human-type receptors and efficient replication in mammals. Other mutations in NA, M2 and NS genes were also found. Although sustained human-to-human transmission has not been conclusively established, limited human-to-human transmission of the H7N9 virus remains possible. Intensified surveillance for the H7N9 virus in humans and animals is needed to answer questions about the viral origin, spread and potential threat.
Animals ; Birds ; virology ; China ; epidemiology ; Humans ; Influenza A virus ; genetics ; Influenza in Birds ; virology ; Influenza, Human ; transmission ; virology ; Mutation

Animals ; Birds ; China ; Humans ; Influenza A Virus, H7N9 Subtype ; pathogenicity ; Influenza in Birds ; epidemiology ; virology ; Influenza, Human ; epidemiology ; virology

Wild birds (mainly Anseriformes and Charadriiformes) are recognized as the natural reservoir of avian influenza viruses (AIVs). The long-term surveillance of AIVs in wild birds has been conducted in North America and Europe since 1970s. More and more surveillance data revealed that all the HA and NA subtypes of AIVs were identified in the wild ducks, shorebirds, and gulls, and the AIVs circulating in wild birds were implicated in the outbreaks of AIVs in poultry and humans. Therefore, the AIVs in wild birds pose huge threat to poultry industry and human health. To gain a better understanding of the ecology and epidemiology of AIVs in wild birds, we summarize the transmission of AIVs between wild birds, poultry, and humans, the main results of surveillance of AIVs in wild birds worldwide and methods for surveillance, and the types of samples and detection methods for AIVs in wild birds, which would be vital for the effective control of avian influenza and response to possible influenza pandemic.
Animals ; Animals, Wild ; virology ; Birds ; virology ; Humans ; Influenza A virus ; genetics ; isolation & purification ; physiology ; Influenza in Birds ; epidemiology ; transmission ; virology ; Influenza, Human ; epidemiology ; transmission ; virology ; Sentinel Surveillance ; veterinary

influenza virus can infect humans and cause disease. The clinical presentation of human infection is usually mild, but the infection caused by A(H5N1) avian influenza virus occurring initially in Hongkong in 1997 or the A(H7N9) virus isolated first at the beginning of this year in China is severe and characterized by high mortality. The mortality rate of adolescents and children caused by H5N1 avian influenza is lower than that of adults and the younger the child the lower the mortality rate. A few pediatric H7N9 avian influenza cases recovered soon after treatment. A child was determined to be a H7N9 avian influenza virus carrier. These findings suggested that the pediatric H7N9 avian influenza infection was mild. It is very important to start anti-virus treatment with oseltamivir as early as possible in cases of avian influenza infection is considered. Combined therapy, including respiratory and circulatory support and inhibiting immunological reaction, is emphasized in the treatment of severe cases.
Animals ; Birds ; virology ; China ; epidemiology ; Disease Outbreaks ; Humans ; Influenza A Virus, H5N1 Subtype ; Influenza in Birds ; virology ; Influenza, Human ; diagnosis ; drug therapy ; epidemiology ; virology ; Time Factors

Animals ; Birds ; virology ; China ; epidemiology ; Humans ; Influenza A virus ; classification ; pathogenicity ; Influenza Vaccines ; Influenza in Birds ; epidemiology ; prevention & control ; Influenza, Human ; epidemiology ; prevention & control

OBJECTIVETo evaluate the prevalence of avian influenza virus in various environment and the influence factors for subtype H7 prevalence in live poultry markets.

METHODSWe collected environmental samples from various environments across 11 cities of Zhejiang province between October 2014 and March 2015. Cage surface swabs, chopping board surface swabs, feces, water for cleaning, drinking water and swabs of other surfaces were collected. A total of 6 457 samples were collected, including 4 487 samples from poultry markets, 820 samples from poultry farms, 715 samples from backyard poultry pens, 118 samples from poultry processing factories, 118 samples from wild bird habitats and 86 samples from other sites. The chi-squared test was used to compare virus prevalence among sample types, sites types, and poultry markets types. Binary logistic regression was used to analyze factors on H7 subtype prevalence in poultry markets.

RESULTSOf 6 457 samples, 32.54% (2 101) samples were positive for avian influenza, with 3.67% (237) positive for H5 subtype, 12.02%(776) positive for H7 subtype, 11.77%(760) positive for H9 subtype. Of 237 live poultry markets, 33.8% (80) were positive for H7 subtype. The prevalence of influenza A in poultry processing factories was the highest at 43.72% (101/231) (χ(2)=737.80, P<0.001). Poultry markets were contaminated most seriously by subtype H5/H7/H9 with the prevalence of 27.55% (1 236/4 487) (χ(2)=436.37, P<0.001). Compared with markets with 1 type of poultry, OR was 4.58 (95%CI: 1.63-12.87) for markets with ≥2 types of poultry.

CONCLUSIONLive poultry markets and poultry processing factories were contaminated most seriously by avian influenza. The types of poultry might be the factor which influenced the subtype H7 prevalence in poultry markets.

Animals ; Birds ; Environment ; Feces ; Food-Processing Industry ; Influenza A virus ; isolation & purification ; Influenza in Birds ; epidemiology ; Poultry ; virology ; Risk Factors ; Seasons

Pandemic influenza has posed an increasing threat to public health worldwide in the last decade. In the 20th century, three human pandemic influenza outbreaks occurred in 1918, 1957 and 1968, causing significant mortality. A number of hypotheses have been proposed for the emergence and development of pandemic viruses, including direct introduction into humans from an avian origin and reassortment between avian and previously circulating human viruses, either directly in humans or via an intermediate mammalian host. However, the evolutionary history of the pandemic viruses has been controversial, largely due to the lack of background genetic information and rigorous phylogenetic analyses. The pandemic that emerged in early April 2009 in North America provides a unique opportunity to investigate its emergence and development both in human and animal aspects. Recent genetic analyses of data accumulated through long-term influenza surveillance provided insights into the emergence of this novel pandemic virus. In this review, we summarise the recent literature that describes the evolutionary pathway of the pandemic viruses. We also discuss the implications of these findings on the early detection and control of future pandemics.
Animals ; Birds ; virology ; Communicable Diseases, Emerging ; epidemiology ; history ; virology ; Evolution, Molecular ; History, 20th Century ; History, 21st Century ; Humans ; Influenza A Virus, H1N1 Subtype ; genetics ; Influenza A Virus, H3N2 Subtype ; genetics ; Influenza in Birds ; epidemiology ; history ; virology ; Influenza, Human ; epidemiology ; history ; virology ; Pandemics ; history

Animals ; Birds ; virology ; China ; epidemiology ; Computer Communication Networks ; Epidemiologic Methods ; Influenza A Virus, H7N9 Subtype ; isolation & purification ; Influenza in Birds ; epidemiology ; transmission ; virology

Animals ; Birds ; Communicable Disease Control ; methods ; Disease Outbreaks ; prevention & control ; statistics & numerical data ; Health Planning ; Humans ; Influenza A Virus, H5N1 Subtype ; Influenza in Birds ; epidemiology ; virology ; Risk Factors ; Singapore ; epidemiology

OBJECTIVETo analyze the spatial distribution of highly pathogenic avian influenza (HPAI) and to explore environmental factors associated with HPAI using geographic information system (GIS) techniques in Mainland China.

METHODSDatabases were set up using the information of HPAI during epidemics in 2004, and linked to digital maps at provincial and county administrative layers in the country through the ArcGIS 8.3 software. Spatial cluster analyses, spatial statistics analyses and tracking analyses on epidemic situation of HPAI were implemented. Environmental factors associated with HPAI were also analyzed on data related to weather, vegetation and migratory birds etc.

RESULTSFindings from spatial cluster analyses showed that high incidence area was centralized in 113.261 degrees ordm; east longitude and 23. 119 degrees ordm; north latitude with a radius of 1090.52 kilometers (relative risk= 2.646, P value= 0.001). Spatial statistical analyses showed that HPAI took place mainly in capital cities of provinces and surrounding areas as well as in the circumference areas of arterial rivers, lakes and seacoasts. Results also showed that HPAI occurrences were associated with low air temperature, high relative humidity and high air pressure as well as with east & central migration routes of migratory birds. The average normalized difference vegetation index was 0.36 +/- 0.11 in epidemic areas of HPAI.

CONCLUSIONHPAI was unrandomly distributed and geographically clustered in China.

Animal Migration ; Animals ; Atmospheric Pressure ; Birds ; virology ; China ; epidemiology ; Cluster Analysis ; Environment ; Geographic Information Systems ; Humidity ; Influenza A Virus, H5N1 Subtype ; pathogenicity ; Influenza in Birds ; epidemiology ; Temperature