Avian influenza,also known as avian flu or bird flu,is a disease caused by the influenza A virus,which primarily affects birds but can sometimes affect mammals including humans. Wild aquatic birds are the primary host of the influenza A virus,which is enzootic in many bird populations.
Influenza A virus subtype H5N1 (A/H5N1) is a subtype of the influenza A virus,which causes influenza (flu),predominantly in birds. It is enzootic in many bird populations,and also panzootic. A/H5N1 virus can also infect mammals that have been exposed to infected birds;in these cases,symptoms are frequently severe or fatal.
The 2000s in Hong Kong began a new millennium under the People's Republic of China (PRC).
An influenza pandemic is an epidemic of an influenza virus that spreads across a large region and infects a large proportion of the population. There have been six major influenza epidemics in the last 140 years,with the 1918 flu pandemic being the most severe;this is estimated to have been responsible for the deaths of 50–100 million people. The 2009 swine flu pandemic resulted in under 300,000 deaths and is considered relatively mild. These pandemics occur irregularly.
Influenza A virus subtype H3N2 (A/H3N2) is a subtype of influenza A virus (IAV). Some human-adapted strains of A/H3N2 are endemic in humans and are one cause of seasonal influenza (flu). Other strains of H1N1 are endemic in pigs and in birds. Subtypes of IAV are defined by the combination of the antigenic H and N proteins in the viral envelope;for example,"H1N1" designates an IAV subtype that has a type-1 hemagglutinin (H) protein and a type-1 neuraminidase (N) protein.
The global spread of H5N1 influenza in birds is considered a significant pandemic threat. While other H5N1 influenza strains are known,they are significantly different on a genetic level from a highly pathogenic,emergent strain of H5N1,which was able to achieve hitherto unprecedented global spread in 2008. The H5N1 strain is a fast-mutating,highly pathogenic avian influenza virus (HPAI) found in multiple bird species. It is both epizootic and panzootic. Unless otherwise indicated,"H5N1" in this timeline refers to the 2008 highly pathogenic strain of H5N1.
Transmission and infection of H5N1 from infected avian sources to humans has been a concern since the first documented case of human infection in 1997,due to the global spread of H5N1 that constitutes a pandemic threat.
H5 N2 is a subtype of the species Influenzavirus A. The subtype infects a wide variety of birds,including chickens,ducks,turkeys,falcons,and ostriches. Affected birds usually do not appear ill,and the disease is often mild as avian influenza viral subtypes go. Some variants of the subtype are much more pathogenic than others,and outbreaks of "high-path" H5N2 result in the culling of thousands of birds in poultry farms from time to time. It appears that people who work with birds can be infected by the virus,but suffer hardly any noticeable health effects. Even people exposed to the highly pathogenic H5N2 variety that killed ostrich chicks in South Africa only seem to have developed conjunctivitis,or a perhaps a mild respiratory illness. There is no evidence of human-to-human spread of H5N2. On November 12,2005 it was reported that a falcon was found to have H5N2. On June 5,2024,the first confirmed human case of H5N2 was reported in Mexico.
H7N4 is a subtype of the species Influenza A virus.
The social impact of H5N1 is the effect or influence of H5N1 in human society.
Disease surveillance is an epidemiological practice by which the spread of disease is monitored in order to establish patterns of progression. The main role of disease surveillance is to predict,observe,and minimize the harm caused by outbreak,epidemic,and pandemic situations,as well as increase knowledge about which factors contribute to such circumstances. A key part of modern disease surveillance is the practice of disease case reporting.
The global spread of H5N1 in birds is considered a significant pandemic threat.
The global spread of H5N1 in birds is considered a significant pandemic threat.
The global spread of H5N1 in birds is considered a significant pandemic threat.
Fujian flu refers to flu caused by either a Fujian human flu strain of the H3N2 subtype of the Influenza A virus or a Fujian bird flu strain of the H5N1 subtype of the Influenza A virus. These strains are named after Fujian,a coastal province in Southeast China.
H5N1 influenza virus is a type of influenza A virus which mostly infects birds. H5N1 flu is a concern due to the its global spread that may constitute a pandemic threat. The yardstick for human mortality from H5N1 is the case-fatality rate (CFR); the ratio of the number of confirmed human deaths resulting from infection of H5N1 to the number of those confirmed cases of infection with the virus. For example,if there are 100 confirmed cases of a disease and 50 die as a consequence,then the CFR is 50%. The case fatality rate does not take into account cases of a disease which are unconfirmed or undiagnosed,perhaps because symptoms were mild and unremarkable or because of a lack of diagnostic facilities. The Infection Fatality Rate (IFR) is adjusted to allow for undiagnosed cases.
The global spread of H5N1 in birds is considered a significant pandemic threat.
The 2009 swine flu pandemic in Hong Kong was part of the worldwide pandemic that started with the city's first reported case of influenza A virus subtype H1N1 infection,commonly called swine flu,on 1 May 2009,by a Mexican national who had travelled to Hong Kong via Shanghai. It was also the first reported case in Asia. As of 25 November 2009,there have been 32,301 confirmed cases of swine flu in the city.
Influenza A virus subtype H7N9 (A/H7N9) is a subtype of the influenza A virus,which causes influenza (flu),predominantly in birds. It is enzootic in many bird populations. A/H7N9 virus can also infect humans that have been exposed to infected birds;in these cases,symptoms are frequently severe or fatal. A/H7N9 virus is shed in the saliva,mucous,and feces of infected birds. The virus can spread rapidly through poultry flocks and among wild birds.
Guan Yi is a Chinese virologist. In 2014,he was ranked as 11th in the world by Thomson Reuters among global researchers in the field of microbiology. He obtained his PhD in microbiology at the University of Hong Kong and is now a professor of microbiology at his alma mater. His research on the viral respiratory disease SARS helped the Chinese government avert the 2004 outbreak of this disease. He is the current director of the State Key Laboratory for Emerging Infectious Diseases University of Hong Kong. In early 2017,Guan warned that the H7N9 influenza virus "poses the greatest threat to humanity than any other in the past 100 years".
